Nihilistic Delusions

1. Overview — What Are Nihilistic Delusions?

Nihilistic delusion is a “false belief detached from reality” whose central core is the negation of existence of the self, the body, or the world.
It is not just a gloomy thought like “life is meaningless,” but a belief at the level of:

“I no longer exist.”

“I’m already dead, but my body is still walking.”

“My internal organs are empty, the blood has stopped flowing, my heart no longer works.”

“This world has already ended; everything I see is an illusion / a shell / a temporary hell.”

The key point is: people with nihilistic delusions genuinely believe these things. They are not speaking metaphorically, not joking, not using figures of speech, and they do not change their belief even when there is clear evidence against it.

This is different from typical depression, where patients often say:

“I’m worthless now,” “Life has no meaning.”

They still accept that they “exist,” but feel that they are “worthless.”
In contrast, nihilistic delusion crosses one step further and denies existence itself, for example:

“I no longer exist in this world / I’m already dead / I’m now a walking corpse.”

This kind of content often extends to the body (somatic) as well, for example:

“My guts have rotted away and disappeared, only a hollow cavity is left.”

“My brain has melted away; only an empty skull remains.”

“The blood in my body stopped flowing a long time ago, the system is just moving in a fake, mechanical way.”

Or it extends outward to the external world (world/reality), for example:

“The world has already collapsed; only a waiting room or strange dimension remains.”

“The people around me aren’t real humans, but illusions / puppets / spirits.”

In some cases there is a form that sounds paradoxical but is actually in the same thematic family:

“I cannot die / I am immortal.”

This may sound grandiose, but in the Cotard/nihilistic context it carries the tone of:

“Being stuck in a state that is neither truly alive nor truly dead, punished to never be released.”

Clinically, nihilistic delusions are often discussed together with “Cotard’s syndrome / Cotard’s delusion,”
which is a syndrome where the patient believes that:

They are already dead.

Their body is decaying, disappearing, or no longer functioning.

The world or environment is like hell / an afterlife / an in-between realm.

Points that must be emphasized clearly:

Nihilistic delusion is not a standalone disease name in DSM/ICD.

It is a “type of delusional content”

that appears within several major disorders, such as:

Major depressive episode with psychotic features (especially in severe episodes with psychotic depression)
Schizophrenia / Schizoaffective / Schizophreniform
Bipolar depression with psychotic features
Or psychotic disorder due to another medical condition, such as brain disease, tumors, seizures, dementia, etc.

Why is this important?

Because when a person firmly believes that:

“I’m dead already / I don’t need to eat / I have no organs left,”

they begin to stop eating, stop drinking, stop taking medication, stop self-care, because from their point of view:

“A corpse doesn’t need to eat anything.”

This makes nihilistic delusions, especially in Cotard’s syndrome, considered a life-threatening condition, not just “a strange thought.”

Another crucial distinction is that this is not the philosophy of nihilism.

Someone who believes in philosophical nihilism may say:

“Life has no ultimate meaning.”

But they still recognize that the real world is in front of them, still accept that they themselves exist, and can still function (work, earn money, eat, etc.).

In contrast, a nihilistic delusion is a level where the belief has broken away from consensus reality and directly impairs daily functioning.

In short:

Nihilistic delusions = a fixed false belief that the self/body/world “no longer exists, has vanished, or has ended.”
It is not just sadness, not just philosophy, but a symptom of psychosis, usually occurring in the context of severe depression with psychotic features, or other psychotic disorders related to dysfunction in the brain networks for “self–body–world.”

2. Core Symptoms — Central Features of Nihilistic Delusions

When encountering a “nihilistic delusion” in real clinical practice, it is not just the sentence:

“I’m dead.”

and that’s it. There is a structure to the thought plus clear impact on life, as follows:

2.1 Nihilistic Delusional Content: Broken Down Into 4 Axes

2.1.1 Existential Negation — Denying the Existence of the “Self”

This is the form most people are familiar with.

The patient believes:

“I no longer have a self,” “I’m already dead,” “I have disappeared from this world.”

This is not just feeling numb or dull; it is a belief at the level of conviction.

When the clinician asks:

“But how can you come and sit here talking to me if you’re dead?”

the patient answers in a way that makes sense in their own internal world, for example:

“The body walks by itself; I just no longer exist in the real world.”

“This is like hell / a space between death and annihilation.”

“What you see is just a shell, not the real me.”

How this differs from ordinary hopeless thoughts in depression:

Typical depression:

“I’m worthless now,” “Life is meaningless.”
→ The person still accepts that they “exist,” but feel worthless / hopeless.

Nihilistic delusion:

“I no longer exist,” “Right now I’m already dead.”
→ This denies at an ontological level that their own “existence” is gone.

2.1.2 Somatic Negation — Denying Internal Organs / Inner Body

This axis often expands from existential negation or arises alongside it.

Typical content includes:

“There is no blood inside me anymore; it’s all dried up.”

“My intestines have rotted away and disappeared; my abdomen is just an empty cavity.”

“My heart stopped beating a long time ago, but the body is still moving.”

“My brain has melted and vanished; only an empty skull is left.”

What is observed in clinical practice:

Patients often refuse to eat / refuse to drink, because they believe:

“My digestive system no longer exists; whatever I eat won’t go anywhere.”

Some speak with “logic within their own world,” such as:

“You can feel my pulse? That’s just a strange mechanism of a corpse that hasn’t decayed yet.”

There is a high risk of malnutrition, dehydration, organ failure because they feel there is nothing left to take care of.

Difference from other types of somatic delusions:

Typical somatic delusions:

“There’s a chip implanted in my brain,” “There’s a snake in my abdomen.”
→ The content is that “something extra is present.”

Somatic negation:
Focuses on “no longer there / has dissolved / rotted and lost its function.”
→ This is denial of the existence of body parts.

2.1.3 World Negation — Denying the Existence of the “World / External Reality”

Another deep and disturbing form is not just “I do not exist,” but:

“The world does not exist, either.”

Example content:

“This world is already over; only an empty shell remains.”

“Everyone is an illusion created by my brain.”

“The universe has shattered; I am now in a waiting room for emptiness.”

“Time is no longer moving forward; everything is frozen, and only I am stuck.”

This overlaps with the feeling of derealization (the world feels unreal, everything feels dreamlike), but the difference is:

Derealization: patients tend to say,

“It feels like the world is not real, but I know it’s just a feeling.”

Nihilistic delusion: patients say,

“The world is truly not real,” and
believe it 100%.

2.1.4 Moral/Spiritual Negation — Denial at the Level of “Soul / Moral Worth”

In some cases within the Cotard spectrum, religious/moral overtones are mixed in, for example:

“I am being punished by God / a sacred being; my soul is dead, but I must keep suffering.”

“My name has been erased from the human world; only a shell of me is walking around.”

“I am too sinful to truly die, so I am trapped in this state.”

The emotional tone is severe depression + very high guilt + vivid imagery of punishment, leading to:

A complete loss of self-worth (worthlessness)

Belief that self-care or treatment is meaningless because

“Karma has already passed judgment.”

2.2 Delusional Conviction — Stability of the Belief

The core that makes this a delusion, and not just a strange idea, is:

2. Degree of conviction

No matter how many times you ask, the answer remains the same.

Even if you challenge them to test it, the belief does not change, for example:

“I can hear your heartbeat with my stethoscope; that means it’s still beating.”
→ Patient:
“Exactly, that’s the abnormality of a corpse / hell; it is making fake sounds.”

2. Resistance to evidence — immune to reality testing

The belief is not shaken by direct evidence.

Doctors/family may present many kinds of proof, but the patient still interprets everything to fit the delusion.

3. Very low insight (poor / absent insight)

The patient does not think,

“Maybe I’m ill.”

Instead, they think,

“I understand the truth that others don’t.”

Some see the doctor as someone who is

“lying to themselves that I’m not dead yet.”

Comparison with “dark thoughts” in ordinary people:

A severely stressed person might say:

“I’m so stressed I feel like I’m dead already.”
→ If you ask further, they will admit it is a metaphor.

Delusion: they say,

“It’s not a metaphor; I really am dead,”
and have an internal reasoning system to support it.

2.3 Behavioural Consequences — The Truly Dangerous Part

This is what makes this type of symptom life-threatening, not just odd.

2.3.1 Not Eating / Not Drinking / Not Taking Medication

Beliefs such as:

“Why eat if I’m already dead?”

“There are no intestines; food will just rot inside this body.”

“Blood no longer flows; medication won’t be distributed anyway.”

Consequences:

Rapid weight loss, emaciation, severe malnutrition

Risk of electrolyte imbalance, cardiac complications, low immunity

Some cases require tube feeding / IV nutrition in hospital to save life

This is why cases with Cotard + psychotic depression are often regarded as psychiatric emergencies.

2.3.2 Self-Harm / Suicide

The “weight” of the delusion can go in two directions:

1. “I’m already dead; I don’t feel pain, nothing matters.”
→ Increased risk-taking / self-harm in order to “prove it to others,”
such as jumping from heights, cutting or damaging body parts.

2. “I’m stuck in this state; I have to end it.”
→ Attempted suicide to “end the torment” or “reach complete emptiness.”

Thus, clinically:

Every case where someone says,

“I’m already dead / I no longer exist,”
→ requires immediate, detailed suicide risk assessment.

Even if the patient says,

“Why would I commit suicide if I’m already dead?”
one still cannot be reassured, because there can be other lines of logic driving self-harm.

2.3.3 Neglect of Hygiene / Social Withdrawal

Once they believe:

“I’m not a person / I no longer exist,”

then activities like bathing, brushing teeth, doing laundry, working, talking to others become:

“Meaningless.”

Many patients will:

Not get out of bed

Not talk to anyone / not answer phone calls

Let their home/room become messy and dirty

Family often notice that someone who used to “take care of themselves reasonably well” has turned into someone who “neglects everything.”

Secondary effects:

Increased risk of infection, physical illnesses

Further reinforces the delusion:

“See? I really am rotting / falling apart.”

2.4 Common Associated Symptoms

Nihilistic delusion rarely appears alone; it usually carries other “packages” with it:

2.4.1 Severe Depression

Depressed mood all day

Loss of interest in activities (anhedonia)

Insomnia / hypersomnia

Heavy guilt (guilt delusions such as
“I caused others to die.”)

Severe worthlessness

In many cases, the delusion “fits” the mood (mood-congruent), for example:

“I’m so bad that I might as well be dead,”
“I don’t deserve to exist in this world.”

2.4.2 Severe Anxiety, Agitation

Pacing back and forth, restlessness

Endless worry about “being stuck like this forever”

Conversations are filled with existential questions:

“Where does it go from here?”

“When will this end?”

Some patients fluctuate between numb / sluggish (from depression) and fearful / panicky (from the delusion) throughout the day.

2.4.3 Other Psychotic Symptoms (Hallucinations, Other Delusions)

Especially when occurring in:

Schizophrenia
Schizoaffective disorder
Bipolar disorder with psychosis

There may be:

Auditory hallucinations, such as voices saying:

“You’re dead,” “You have no right to be on this earth,” “This is your punishment.”

Persecutory delusions in parallel, such as:

“A secret organization killed me but pulled my soul back to torture it.”

Or bizarre grandiose delusions mixed in, such as:

“I am a higher lifeform that exists beyond death.”

All of this makes the clinical picture multi-layered, not just a single nihilistic sentence.

3. Diagnostic Criteria — “Practical” Diagnostic Approach

This is crucial: Nihilistic Delusion = a “type of delusional content,”
not a disease name in DSM / ICD with its own separate criteria set like Schizophrenia or MDD.

When clinicians diagnose, they typically use two main levels:

3.1 Level 1: First Confirm That “This Truly Is a Delusion”

It must be distinguished from:

Hopeless thoughts

Metaphorical expressions

Depersonalization / derealization

Religious/philosophical beliefs consistent with the person’s culture

3.1.1 A Practical Delusion Checklist

1. Content clearly contradicts reality

Ordinary people in the same society would not agree, for example:

“I’m dead but still walking.”

“All my organs are gone but I can still speak.”

2. Fixed belief

Does not change even as time passes

The person repeats this belief, and it has a real impact on daily life.

3. Inconsistent with cultural/religious background

For example, belief that “after death, the spirit clings to the body” in a certain religion — if this is a shared cultural belief, it is not a delusion.

But if it’s something like

“Right now I have no existence in any realm at all,”
plus congruent behaviour (not eating, not self-care), this is much more suspicious.

4. Causes functional impairment

Refusing to eat / not working / not socializing because they believe they no longer exist.
This is evidence that it’s not just a random thought; it occupies real-life functioning.

If all four are “yes,” we usually treat it as a delusion, then determine which disorder it belongs to.

3.2 Level 2: Embed It Into a “Primary Disorder”

Because nihilistic delusion is a content, clinicians must place it inside a primary disorder, for example:

3.2.1 Major Depressive Episode with Psychotic Features

In brief, the conditions are:

A clear major depressive episode (sadness, loss of interest, anhedonia, worthlessness, guilt, sleep disturbance, etc.) lasting ≥ 2 weeks

During that episode, delusions / hallucinations emerge

If the delusional content matches the depressed mood, such as:

“I am dead because I am worthless,”
“My body is rotting as punishment,”

→ this is called mood-congruent psychotic features.

Many papers on Cotard / nihilistic delusions have found that most cases are tied to psychotic depression, especially in middle-aged and older adults.

3.2.2 Schizophrenia / Schizoaffective / Other Primary Psychotic Disorders

In this situation we see:

Multiple positive symptoms, such as:

Hallucinations
Persecutory / grandiose / referential delusions
Disorganized speech / behaviour

The nihilistic delusion may be one of several themes of delusion, for example:

Believing that a secret organization has killed them (persecutory + nihilistic)

Believing they are a special being above death (grandiose + nihilistic)

Clinicians then apply the full criteria for Schizophrenia / Schizoaffective / Schizophreniform, etc., according to DSM-5-TR, for example:

Duration ≥ 6 months (schizophrenia)

At least 2 of: delusions, hallucinations, disorganized speech, disorganized/catatonic behavior, negative symptoms

Marked decline in functioning (work / relationships / self-care)

Then nihilistic delusion is used as supporting information about the theme of delusional content.

3.2.3 Psychotic Disorder Due to Another Medical Condition

Consider this when we find a case like:

Clear history of a neurological/brain condition such as:

Brain tumor
Stroke
Epilepsy
Dementia
Infection/autoimmune disease affecting the CNS

And later the person develops nihilistic delusions.

Clinicians must consider:

Could this be secondary psychosis due to a medical illness (not primary schizophrenia)?

Key aspects to examine:

Temporal link: psychotic symptoms begin after the medical illness / flare in parallel with it

No strong evidence of a pre-existing primary psychotic disorder

Physical exam, neurological exam, and brain imaging support a medical cause

Once it fits this frame, treatment focuses on:

Treating the brain/medical disease as the primary target

Using antipsychotics / mood agents as adjuncts to control psychotic symptoms

3.2.4 Substance/Medication-Induced Psychotic Disorder

We consider this pattern if:

Nihilistic delusions begin after using certain substances or medications, such as:

High-dose steroids
Some stimulants
Drugs of abuse, e.g. stimulants, hallucinogens, etc.

Symptoms are linked to the period of drug action or withdrawal.

Clinicians will evaluate:

The time relationship (onset / offset) with substance use

History showing that when the person is not using substances, they did not have this type of psychosis before.

3.3 Distinguishing from Depersonalization / Derealization / Philosophical Thoughts

This is where many writers get confused, so let’s make it clear:

3.3.1 Depersonalization / Derealization (DP/DR)

Patients say things like:

“I feel like I’m not myself.”

“I feel like the world isn’t real, like I’m in a dream.”

But insight is preserved:

“I know it’s just a feeling, but I can’t get out of it.”

There is usually no extreme behaviour such as:

“I don’t eat because I think I’m dead.”

Summary:

DP/DR = disturbance of the feeling of reality
Nihilistic delusion = disturbance of the belief about reality

3.3.2 Philosophical Nihilism

Some people study philosophy and come to believe that:

“Life has no true meaning,” “Moral values are constructs.”

But they still live their lives, work, care for themselves, and plan for the future.
Their belief does not make them “fall out of consensus reality.”

This is not a delusion, but a worldview / personal philosophy.

3.4 Insight, Severity, and the Diagnostic “Threshold”

In reality there is a spectrum:

Some people:

Are 50% convinced “I’m probably dead,”

And 50% still questioning “Maybe I’m overthinking?”

This might be called overvalued ideas or poor insight, but not yet a full delusion.

Once the belief becomes so rigid that:

It does not budge despite evidence, and

There are extreme behaviours following the belief,

→ At that point we call it a full delusion.

Clinically, therefore:

The clinician will repeatedly ask direct questions to examine the “core belief.”

Observe behaviours that follow the belief (e.g. refusing to eat because they believe they are dead).

Use an overall global clinical judgment to make the diagnosis.

4. Subtypes or Specifiers — Subtypes / Spectrum Labels Commonly Used

A) Cotard’s syndrome / Cotard’s delusion (Common Overall Pattern)
The core is nihilistic delusions (self/body/world) and may include “immortality thoughts” as well.
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B) The “Cotard Type 1 / Type 2” Distinction (Found in the Literature)

Type 1: Predominantly “pure nihilistic delusion,” with almost no prominent depressive mood.

Type 2: Mixed symptomatology, including depression, anxiety, hallucinations, etc.

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C) DSM-Style Specifiers (Indirectly Relevant)
If within Major Depression: “with psychotic features” and then consider mood-congruent vs mood-incongruent (this conceptual distinction is often discussed in reviews about nihilistic delusions in the context of depression).
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5. Brain & Neurobiology — Brain and Possible Mechanisms in Nihilistic Delusions

To be straightforward:

Research on nihilistic delusions / Cotard’s syndrome is still mostly case reports, case series, and small reviews, not large trials.

So there is still no single model that explains every case. What we have now are “patterns” and “plausible hypotheses” from several domains:

Neuroanatomy (brain regions)
Neurochemistry (dopamine / glutamate / GABA, etc.)
Network neuroscience (DMN, salience network, thalamocortical circuits)
Cognitive models (prediction error / reality monitoring)

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To structure an article systematically, we can break this into 4 axes (A–D), but with more detail and general delusion theory added.

5.1 A) Self-Referential Network & Reality Monitoring Failure

Core concept:
The brain regions that generate the sense of “this is me” plus those that check “where do my thoughts/feelings/perceptions come from” malfunction → the brain wrongly concludes:

“I do not truly exist / my body is destroyed / the world has ended.”

5.1.1 What Is Self-Referential Processing?

Normally, our brain has networks that process “self-related” information, such as:

Medial prefrontal cortex (mPFC)
Posterior cingulate cortex (PCC) / precuneus
Inferior parietal lobule

These networks are involved in:

Self-reflection
Autobiographical memory
Evaluating and interpreting events from the perspective of “me”

Together, they are often grouped into the concept of the Default Mode Network (DMN), which is related to self, mind-wandering, and internal narrative.
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In people with Cotard / nihilistic delusions, it has been proposed that:

Self-related networks function abnormally → the sense of “self” becomes blurred or unstable.

When the self is not stable, the brain tries to “find an explanation” → the result is an extreme belief:

“I have no self anymore,” or “My body has vanished.”

To put it simply:

Self-network = the system writing “my script” in the background.
When the script is severely corrupted, the story the brain produces is something like:
“I’m no longer in this story.”

5.1.2 Reality Monitoring Failure — Not Distinguishing Thought/Feeling from Reality

Reality monitoring is the ability to differentiate:

What I “think / imagine”

What actually happens in the external world.

Dysfunction of the frontal-temporal circuitry (especially prefrontal and temporal association areas) has been proposed as a core of delusions in general: the brain misattributes the “source” of experience, so bizarre thoughts are treated as solid facts.
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Combined with distortion in the self-network, we get:

A sense of alienation from self/body/world (a weird internal signal)

A faulty reality monitoring system

The brain then interprets it as:

“If it feels this strange, then ‘I’ must not actually exist.”

This is the cognitive-neuroscience background behind the simple phrase:

“The brain flags itself as unreal / non-existent.”

5.2 B) Disconnection: Perception + Emotion Out of Sync (A “Cousin” of Capgras)

Another model is borrowed from explanations of Capgras delusion (believing loved ones have been replaced by impostors), often described with the two-factor theory and disconnection hypothesis:

Perceptual recognition (e.g. recognizing a face, seeing one’s own reflection) is intact → ventral visual stream is fine.
But the affective response that should accompany it (familiarity, warmth, attachment) does not appear, because the connection to the amygdala / limbic system is damaged → resulting in the feeling that

“The face looks the same, but it’s not really them.”
The brain must explain this anomaly → it creates a delusion:

“They must have been replaced by someone else.”
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With Cotard / nihilistic delusions, the logic is similar but inverted:

When “feeling oneself” (through interoception, heart beating, breathing, body warmth, etc.),

The emotional signal attached to “being alive” might be missing (due to depression plus limbic disruption).

The brain experiences an extremely strange phenomenon:

“I can perceive myself, but I have no feeling of being alive at all.”

Then it composes a narrative:

“Then I must already be dead / my body is hollow / the world has lost its reality.”

This framework is consistent with reports indicating that Cotard syndrome is associated with fronto-temporo-parietal + limbic circuits that integrate bodily perception with emotion.
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5.3 C) Brain Regions / Lesions Found in Neurological Cases

Neuroimaging reviews of Cotard’s syndrome roughly conclude:

In most cases, routine brain scans (CT/MRI) show no obvious lesion.

But when abnormalities are found, recurring patterns include:

Frontal lobe (dorsolateral prefrontal, orbitofrontal) – involved in judgment, belief evaluation, motivation.
Temporal lobe – involved in memory, emotion, self-representation.
Parietal lobe – involved in body schema, spatial integration.
Some cases show abnormalities at the level of the fronto-temporo-parietal circuitry as a whole.
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Some summaries go as far as to describe Cotard’s syndrome as a:

“Disorder of the fronto-temporo-parietal network,”

accompanied by limbic/subcortical dysfunction affecting affective modulation.

There are also reports of Cotard/nihilistic delusions occurring in the context of:

Stroke, especially in the right parietal/temporal regions

Epilepsy (especially temporal lobe epilepsy)

Various dementias

Parkinson’s disease / other neurodegenerative disorders
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All of this supports the idea that:

If the network that “constructs self + body + world” is damaged or poorly connected,
a nihilistic reality (“no me / no world / I’m a corpse”) can plausibly be generated.

5.4 D) Connection with Severe Depression and the Circuit of Hopelessness

This is crucial, because from an epidemiological standpoint:

Many studies report that most Cotard / nihilistic delusions occur in the context of “major depression with psychotic features,” especially in middle-aged and elderly individuals.
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One model to explain this is:

1. Depression circuits are dysfunctional

Hypoactivity in some prefrontal regions

Hyperactivity in limbic regions such as the amygdala

Disturbances of monoamines (serotonin, norepinephrine, dopamine)
→ leading to a mood state of deep depression, hopelessness, guilt, worthlessness
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2. Extreme hopelessness + guilt → nihilistic delusional content

DSM-5-TR itself recognizes that psychotic features in depression are often “mood-congruent”: content about sin, guilt, death, illness, and bodily destruction.
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For some individuals, hopelessness goes as far as:

“There’s no way I can ever redeem myself.”

“I don’t deserve to exist.”

“My life has been destroyed to the point I’m just a walking corpse.”

The brain converts this “emotional truth” into “factual truth,” then forms a nihilistic delusion.

3. Drive/motivation circuits collapse → “walking corpse” behaviour

Some papers on delusional depression propose that psychotic depression is a “disorder of the drive”: systems for drive (eating, sleeping, sexual drive, social drive) are almost entirely suppressed → behaviour looks like that of someone already dead: lying still, not eating, not caring for oneself. The brain then uses this behavioural picture to reinforce the belief:

“I must be dead.”
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5.5 E) Meta-Level Delusion Models: Prediction Error, Dopamine, Glutamate, GABA

If you want to write for Nerdyssey tying into broader neuroscience of delusions, you can use the predictive processing + aberrant prediction error model:

The brain normally works as a “predictive machine”:

It predicts what will happen (prediction).
Compares predictions to sensory input.
If mismatch occurs → prediction error arises, and the world model gets updated.

In psychosis, some propose that:

Dopamine systems (especially mesolimbic) and glutamate/GABA systems are dysregulated.
This alters the “weight” of prediction error: small or irrelevant signals get overly amplified → become unusual experiences with aberrant salience.
The brain must create a “story” to explain these anomalies → delusions.

PMC+2ORCA+2

For nihilistic delusions:

Experiences like “numb body / no feeling / world looks strange / self feels unlike self” = large anomalies.

Prediction error spikes, but the prefrontal/self networks that interpret these signals are unstable.

The brain proposes a hypothesis:

“The simplest explanation is — I’m dead / I don’t exist / the world has ended.”

At the neurotransmitter level:

Dopamine → aberrant salience, tied to assigning “importance” to odd thoughts/experiences.

Glutamate / NMDA → involved in prediction error, learning, synaptic plasticity.

GABA → inhibitory “brake” system; if balance with glutamate is lost, network noise rises and belief filtering deteriorates.
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5.6 F) Thalamocortical Dysrhythmia & Large-Scale Networks

Recent work has also shone a spotlight on:

The thalamus as a “hub” that regulates rhythmic activity and switching between large-scale networks such as the DMN, salience network, and central executive network.

When thalamocortical dysrhythmia occurs → the balance between “self-network,” “salience network,” and “executive network” collapses → consciousness and reality perception become distorted, enabling psychotic states.
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Because nihilistic delusions are a form of psychotic content, it is plausible that, beyond the fronto-temporo-parietal network, there are issues with network orchestration from the thalamus as well.

Section 5 summary (short, for key takeaways):

There is no single “spot in the brain” that causes nihilistic delusions, but recurring patterns show dysfunction in networks for self, body, world, plus limbic/emotional and thalamocortical rhythms.

Severe depression / psychotic depression provides an emotional background of hopelessness and worthlessness that pushes delusional content toward

“I have no value → I do not exist.”

At the molecular level, the picture resembles psychosis generally: dopamine / glutamate / GABA dysregulation + abnormal predictive processing, so the brain creates a “story of emptiness” to fill the gap of strange experiences.

6. Causes & Risk Factors — In-Depth Causes / Risk Factors

This section essentially answers:

“Why do some people with depression or psychosis not develop nihilistic delusions,
while others end up at ‘I’m already dead’?”

We don’t have one perfect answer yet, but large-scale literature suggests a combination of:

Major psychiatric disorders (depression / schizophrenia spectrum / bipolar, etc.)
Neurological/medical conditions affecting the brain
Certain drugs/substances
Personality/temperamental/biological vulnerabilities
Psychosocial triggers such as stress, trauma, social isolation

6.1 A) Psychiatric Disorders Commonly Associated

6.1.1 Major Depression with Psychotic Features (Psychotic Depression)

From various reviews:

Most Cotard / nihilistic delusions occur in the context of major depression with psychotic features, especially in people older than 25, middle-aged, and elderly.
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Characteristics:

A full major depressive episode

Alongside delusions/hallucinations that are usually mood-congruent, such as:

Guilt
Illness / bodily destruction
Poverty / total ruin
Death / non-existence (nihilism)

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Factors that may increase the probability of a nihilistic theme:

Extremely high levels of hopelessness

A self-interpretation pattern of extremely low self-worth

Falling out of life routines to the point of resembling “someone with no life” — lying all day, doing nothing, not eating → reinforcing the belief of being a “corpse.”

6.1.2 Schizophrenia Spectrum Disorders

Even though psychotic depression is “number one,” nihilistic delusions are also found in:

Schizophrenia
Schizoaffective disorder
Schizophreniform disorder

These cases usually have:

Multiple delusional themes mixed together: persecutory, grandiose, referential, somatic, etc.

Nihilistic delusion is one part of a “psychosis package” rather than the sole, dominant content.
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In the schizophrenia group:

Mechanisms lean more toward dopaminergic / glutamatergic dysregulation + disorganized self-network than purely mood-based.

But if negative symptoms (amotivation, anhedonia, social withdrawal) are severe, they may overlap with the picture of “lifeless / hollow shell,” making nihilistic themes easier to form.

6.1.3 Bipolar Disorder (Depressive Phase) and Other Mood Disorders

Nihilistic delusions have been reported in:

Bipolar depression with psychotic features

Some cases of postpartum depression

Rarely, in combination with severe anxiety/OCD

Overall: any mood disorder that can progress to psychotic depression has the potential to generate nihilistic content, though these are less frequent than in unipolar MDD.
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6.2 B) Neurological / Medical Conditions Affecting the Brain

The literature clearly shows that Cotard / nihilistic delusions are not purely “primary psychiatric” — they also appear in patients with a variety of brain conditions, such as:
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Neurodegenerative disorders

Alzheimer’s disease
Frontotemporal dementia
Parkinson’s disease / Lewy body dementia, etc.

Epilepsy

Especially temporal lobe epilepsy
Psychotic episodes with nihilistic content may occur after seizures.

Stroke / vascular lesions

Especially right parietal / temporal / frontal lesions
Underlying deficits in body schema, spatial integration, and awareness can contribute.

Brain tumors / space-occupying lesions

Particularly those compressing or damaging the fronto-temporo-parietal network.

Infections / inflammatory / autoimmune CNS disorders

Various forms of encephalitis
Demyelinating diseases such as multiple sclerosis
Autoimmune encephalitis (e.g. anti-NMDA receptor encephalitis) — although cases are fewer, unusual psychoses can appear.

Looking across these cases, some researchers propose:

“Regardless of the specific disease, if it significantly hits the self-body-world network + limbic + thalamocortical circuits, it can open the door to Cotard/nihilistic delusions.”
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6.3 C) Drug/Substance-Related Cases

Cases where medications or substances directly trigger nihilistic delusions are relatively few, but literature reports include:
SpringerLink+2Medical News Today+2

Use of dopaminergic medications (e.g. for Parkinson’s disease) that induce psychosis, with content shifting toward nihilistic themes

Use/withdrawal of high-dose steroids in some individuals

Use of drugs that affect the brain/immune system, leading to encephalopathy plus psychosis

Regarding substances of abuse: psychosis from stimulants, hallucinogens, or NMDA antagonists (e.g. ketamine) theoretically fits, since they directly affect dopamine and glutamate. However, classic nihilistic cases directly attributed to substances are still relatively rare compared to typical paranoid psychosis.

Clinically important:

Whenever nihilistic delusions are seen, clinicians must always ask about medications/substances.

Distinguish between:

“The substance triggered the psychosis,”

“The substance is being used on top of a pre-existing disorder.”

6.4 D) Psychosocial Stressors

Even though we talk a lot about brain and chemistry, real-life stressors are equally heavy, especially in people with existing vulnerability.

Stressors commonly described in case reports include:

Loss of a loved one (bereavement, grief)
Divorce / sudden loss of social status
Severe financial problems
Social isolation, moving to a new place, loss of support network
Severe and persistent sleep deprivation
Traumatic events or repeated abuse

In people with backgrounds such as:

A history of mood or psychotic disorders
Or a family history of such conditions

The collision of a major stressor with a biologically vulnerable brain can precipitate:

Psychotic depression
Or a psychotic break in the schizophrenia spectrum

which is then followed by nihilistic delusional content.

Recent reviews on Cotard in depression emphasize that focusing only on psychiatric diagnosis without considering life context may lead to incomplete treatment, because some stressors remain and continue to drive depression.
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6.5 E) Personality / Genetics / Cognitive Style

There is no direct data on a specific “genetic risk for nihilistic delusions,” but we can infer from:

Their association with depression / bipolar / schizophrenia, all of which have polygenic genetic backgrounds.

Where there is a family history of mood/psychotic disorders, the likelihood of similar vulnerability in descendants increases.

Regarding personality and cognitive style:

Those with a pattern of high self-criticism, rumination about their own faults, or schemas like

“I am worthless / I do not deserve to exist”
may have an internal narrative that more easily pushes depression toward
“I do not exist → I am like a corpse.”

People with strong existential thinking or long-standing interest in death/emptiness may already have this “language in their head.” When the brain malfunctions + mood collapses → content easily flows into this channel.

All of this is still at the level of hypothesis, not definitive evidence, but it can be used narratively in an article to explain:

“Not everyone with severe depression becomes Cotard, but in people with a certain personality + thinking pattern + genetics + vulnerable brain, the risk is higher.”

6.6 F) Integrated Model: Vulnerability–Stress–Brain

To close this section in a structured way (and to turn it into an infographic), we can narrate it in three layers:

Vulnerability (Baseline)

Genetic loading for mood/psychotic disorders
Fragility of the fronto-temporo-parietal network / self-network (due to brain structure, previous injury, etc.)
Personality/cognitive style characterized by self-criticism and hopelessness

Stressors & Triggers

Severe life events: losses, isolation
Brain/medical illnesses
Drugs/substances affecting the nervous system
Sleep deprivation, lack of self-care

Brain Response & Clinical Episode

Dysregulated firing in dopamine / glutamate / GABA systems → prediction error surges

The self–body–world networks plus thalamocortical rhythms lose balance

Mood plummets into psychotic depression or another psychotic break

The sense of self destabilizes + reality monitoring collapses → the brain generates an extreme belief:

“I’m dead / I have no self / my body has collapsed / the world has ended.”

Behaviour aligns with the belief: not eating, not drinking, withdrawal, self-harm risk.

This perspective helps readers understand that nihilistic delusions do not appear “out of thin air,” but rather at the intersection of:

A vulnerable brain + a hopeless mind + a life hit by major stress + a nervous system responding in a dysregulated way.

7. Treatment & Management — Practical Treatment and Management

The main principle: treat with a “Crisis + Cause” approach:

First, manage acute danger.

Then treat the underlying disorder (depression / schizophrenia / medical cause).

A) Safety First (Risk Management)

Conduct a thorough assessment of suicide / self-harm risk.

Assess refusal of food/water/medication → some patients require inpatient hospitalization due to high medical risk.
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B) Medications (Chosen According to the Primary Disorder)

For psychotic depression: typically use antidepressant + antipsychotic together, with close follow-up.
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For the schizophrenia spectrum: the approach leans on antipsychotics as the core, with additional agents as needed.

For suspected medical/substance-induced psychosis: treat the underlying cause + stop or adjust the offending substance/drug.

C) ECT (Electroconvulsive Therapy)

In many publications, especially in psychotic depression / Cotard syndrome, ECT is often reported as effective and relatively fast-acting compared with the severity and life-threatening risk of the patients (with appropriate consideration of indications and contraindications on an individual basis).
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D) Psychotherapy / Long-Term Care

During acute, severe episodes: rational psychotherapy is often limited because the core is a delusion.

Once symptoms stabilize: focus on psychoeducation, relapse prevention, stress/sleep management, and functional rehabilitation.

8. Notes — Important Points

Nihilistic delusion is not the same as “philosophical thinking” (e.g. intellectual nihilism) — here it is a clinical symptom with false, fixed, life-impairing belief.

It must be distinguished from depersonalization/derealization: DP/DR patients usually “know it feels strange” (insight partially preserved), whereas in delusion they believe it is literally true.

Red flags to highlight in an article:
Refusing food/water, firmly stating death/non-existence, severe neglect of the body, self-harm risk → these warrant immediate evaluation by a mental health professional.
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Read Schizophrenia

References

Debruyne H, Portzky M, Van den Eynde F, Audenaert K. Cotard’s syndrome: a review. Current Psychiatry Reports. 2009;11(3):197–202. Journal of Neuropsychiatry

Swamy NC, Sanju G, Pookala S. An overview of the neurological correlates of Cotard syndrome. Actas Españolas de Psiquiatría. 2007;35(4):299–306. SciELO España

Grover S, Aneja J, Mahajan S, Varma S. Cotard’s syndrome: Two case reports and a brief review of literature. Journal of Neurosciences in Rural Practice. 2014;5(3):288–291. PMC+1

Machado L, et al. Cotard’s syndrome and major depression with psychotic symptoms. Revista Brasileira de Psiquiatria. 2013;35(1):95–96. SciELO+1

Ramírez-Bermúdez J, et al. Cotard Syndrome in Neurological and Psychiatric Patients. Journal of Neuropsychiatry and Clinical Neurosciences. 2010;22(4):409–416. Psychiatry Online

Kelly CA. A clinical and neuro-radiological study of nihilistic delusions. Doctoral thesis, University College London; 1994. UCL Discovery+1

Kreczyńska LM. Cotard’s syndrome – review of current knowledge. Psychiatria Polska / Monz. 2023 (online). Monz

Somvanshi S, et al. Nihilistic delusion in the context of major depressive disorder: case report and review. American Journal of Geriatric Psychiatry. 2019. AJGP Online+1

Koreki A, et al. You are already dead: Case report of nihilistic delusions in cenesthetic schizophrenia. Perspectives in Psychiatric Care. 2023. PMC+1

Wiśniewska AM. Cotard’s Syndrome in Depression: A Literature Review. Archiv Euromedica. 2024;14(4). Archiv-EuroMedica

“Psychotic depression” – overview of mood-congruent psychotic features (including nihilism) in Wikipedia and DSM-5-related sources. Wikipedia+2floridabhcenter.org+2

Nature / Research Intelligence. Cotard’s Syndrome and related delusional disorders – topic summary. Nature

Vu A. Cotard syndrome. LITFL – Life in the Fast Lane (critical care compendium). 2018. Life in the Fast Lane • LITFL

nihilistic delusion, nihilistic delusions, delusion of negation, Cotard syndrome, Cotard’s syndrome, Cotard’s delusion, walking corpse syndrome, le délire des négations, psychotic depression, major depressive disorder with psychotic features, mood-congruent psychotic features, mood-incongruent psychotic features, somatic nihilistic delusion, existential nihilistic delusion, body-focused nihilistic delusion, delusional depression, schizophrenia spectrum, schizoaffective disorder, bipolar depression with psychosis, psychotic disorder due to another medical condition, fronto-temporo-parietal network, self-referential processing, depersonalization vs delusion, derealization vs delusion, reality monitoring, aberrant salience, dopamine dysregulation, glutamate GABA imbalance, ECT for psychotic depression, antipsychotic treatment, Cotard type 1, Cotard type 2, life-threatening psychosis, refusal to eat, high suicide risk

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