Neurology of Delusions
Orrin Devinsky
Delusion
 Pathological,
 Cannot
 Not
fixed idea
be overturned by evidence
culturally or religious condoned
 Can be bizarre or non-bizarre
 Occur in primary psychiatric disorders
(schizophrenia, delusional disorders) and
secondary neurological disorders
Delusions in Psychiatry

Schizophrenia - often bizarre
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Influence, persecution/paranoia, self-significance
Psychosis due to mood disorder
Delusional disorder - prominent non-bizarre
delusions lasting > 1 month

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Erotomania
Grandiose
Jealous
Persecutory
Somatic
Mixed
Delusions in Neurological
Disorders

Generalized Neurological Disorders
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Neurosyphilis (grandiose)
Dementia - Alzheimer’s, Multi-infact, Lewy body disease
Parkinson’s disease
Toxic-metabolic
Epilepsy – Postictal & interictal
Focal Neurological disorders

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Stroke
Tumor
Head trauma
Epilepsy – Interictal & postictal
Content Specific Delusions in
Neurological Disorders

Delusional misidentification syndromes
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Reduplicative paramnesia
Capgras
Fregoli (a stranger is believed to be a familiar person)
Othello (delusional jealousy)
De Clerambault (erotomania)
Cotard (belief one is dying or dead)
Content Specific Delusions:
Poles of Familiarity

Loss of familiarity

People
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Places
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Capgras
Mirror sign
Foreign reduplicative paramnesia (home is considered a duplicate
in another location)
Disorientation for place (familiar place exists in another location)
Hyperfamiliarity

People


Fregoli (a stranger is believed to be familiar)
Places

Reduplicative paramnesia (foreign place is considered familiar
location)
Content Specific Delusions:
Neuropsychiatric Pendulum
 Before
1975 – psychiatric
 Early 1990’s increased awareness of
neuro causes - ~40% of cases
 ‘02 Mayo Clinic review of Capgras only 2/47 (4%) psychiatric! (Joseph, Arch
Neuro)
Anatomy of Delusions:
Bifrontal & Right Hemisphere
R
hem plus bifrontal - post-traumatic Capgras
 Benson
et al, 1976
 Alexander et al, 1979
 Delusions
after R stroke (Levine & Grek, 1984)
9
patients - reduplication of place,
distortions/condensations of events
 Tendency for frontal & temporal
 Most significant finding was baseline atrophy’

2 HIT: R focal on diffuse
 Faulty
reasoning and memory
 Misrepresentations
of past events
Reduplicative Paramnesia


1903 - first described by Pick as a memory disorder
A place simultaneously exists in two or more
physical locations

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Unfamiliar place (hospital) is in home town
Associated with R hemisphere dysfunction
 Benson et al 1976 & Ruff & Volpe, 1981.

RHDamage BHDamage
36 (52%)

28 (41%)
LHDamage (Feinberg, 1989)
5 (7%)
<.0001 (7x)
With neurological lesions – R frontal or parietal
Capgras’ Patient (’23 & ‘24)
53 yo woman, paranoid megaolmaniac (royal
lineages, wealth) dress-designer, onset of paranoia
after 4/5 children died. Daughter and husband
imposters. Filed for divorce. Went to police to
report underground children. Police department
replaced multiple times with imposters. She was
replaced by an imposter.
Recognized that it was especially for familiar people
Initially postulated an “agnosia of identification”;
struggle for all sensory images between poles of
familiar and strange.
A year later - Oedipal conflict
Capgras Syndrome & Right
Hemisphere
 Hayman
& Abrams 1977 & Alexander et al, 1979
 Review of literature (Feinberg ,1989)
RHDamage
8 (32%)
BHDamage
16 (62%)
LHDamage
2 (7%)
<.06 (4X R>L)
Capgras Syndrome: Mechanisms
 Opposite
of prosopagnosia (Young & Ellis)
 Prosopagnosia
- no conscious recognition of
familiar face but a GSR to familiar face
 Capgras - conscious recognition of familiar face
but no GSR to familiar face
 Hirsten
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
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& Ramachandran’s patient
Absence of GSR
Knew his dad was dad by phone
Thought same person in photo was different if gaze different
Disconnection of facial recognition area from emotional area that
generates the “glow” or “sparkle”
Capgras and Familiarity: Why
 Ramachandran
- missing the glow;
strangers don’t evoke that - no
‘mismatch’
 If so, why don’t they say - “its my wife,
but I don’t feel like its my wife”
 Patient
X - somatic delusions, emotional
disconnection but verbally aware after R
Ant TL
Familiarity & The Temporal Lobe
 Perirhinal
cortex (ant parahippocampal
gyrus) - familiarity of faces and objects;
 Patient
NB - Temporal resection of L
perirhinal cortex for epilepsy with sparing
of hippocampus. Impaired familiarity,
preserved recollection. (Bowles et al, 2007)
 Posterior
parahippocampal gyrus familiarity of places
Déjà vu: Familiarity & The
Temporal Lobe
 Déjà
vu – transient feeling of familiarity
 Too
brief to be a delusion, yet if it
persisted…
 Déjà
vu - temporal lobe foci, R>L
Familiarity & The Temporal Lobe
 Lesions
outside the right temporal lobe may
cause non-delusional hyperfamiliarity
syndromes by disinhibiting emotional
familiarity
 Lesions that destroy or disconnect the right
perirhinal cortex may impair familiarity
Capgras and Dementia
 Mayo
clinic - 10 year review of Capgras
and misidentification
 47 cases; 37 (81%) had a degenerative
disorder (mean age 72 yo) vs those
without (51 yo)
 Visual hallucinations - 30/38 with
degenerative vs 2/9 (p=0.03) without
 Lewy Body Disease - 26 patients!
Capgras & Lewy Body Disease?
 Lewy
Body Disease
 Progressive
cognitive decline, often frontal fxn
 Marked fluctuations in alertness and attention
 Parkinsonian motor syndromes (decreased
spontaneity, rigidity)
 Visual hallucinations - correlates with Lewy Bodies in
amygdala, parahippocampal and inferior temporal cortices

Two key hits
 Face
and emotional recognition
 Impaired self-monitoring to detect errors
Hyperfamiliarity
 Patient
1 - left lateral temporal venous infarct
& GTC - prosopaganoisa selectively affecting
unfamiliar faces. (Vuileumier, 2003)
 Patient 2 – 32 yo man, bilateral F-T epilepsy,
cluster of >10 CPS, hyperfamiliarity for faces
lasting ~48 hrs
 Patient GP - 46 yo policeman. Déjà vu, fear
for 6 mos. CPS & single GTC. Since then
hyperfamiliarity for faces.
Hyperfamiliarity
Seven patients reported
All had TCS or epilepsy
Most with Left hemisphere or bilateral
pathology, usually affecting temporal lobe
Déjà vu and HFF result from increased activity
in right relative to the left medial temporal
lobe areas, consistent with the dominant role
of the right medial temporal regions in
familiarity experiences
Frontal Pathology in
Delusions (Feinberg et al, 2005)
 29
patients with misidentificationreduplication syndromes
 Exclusively
frontal lesions in 10/29 (34.5%)
cases
 Four with right frontal
 Six with bifrontal lesions
 None had lesions sparing the frontal lobes
Frontal Pathology in
Delusions
 Nearly
ubiquitous in delusions
 Impaired functions: theory of mind, decision
and prediction making, time estimation and
sequencing & working memory.
 Inability to monitor self and recognize and correct
inaccurate memories and familiarity assessments.
 The resistance of delusions to change despite clear
evidence that they are wrong likely reflects frontal
dysfunction.
Anosognosia:
A Delusional Disorder?
 Unawareness
of neurological deficit: vision
(Anton’s syndrome) or movement (anosognosia
for hemiplegia)
 Inability of self to recognize blindness or
hemiplegia is strikingThe resistance of delusions
to change despite clear evidence that they are
wrong likely reflects frontal dysfunction.
 Often confabulate: “it’s just bad lighting”, “can
move fine”
 Resists rational explanation or visual
demonstration
Anosognosia:
A Delusional Disorder?
 Some
patients deny ownership of their limb
(asomatognosia), ? it belongs to someone else.
 Asomatognosia - delusion with loss of limb’s
relation to self: Capgras affecting the arm.
 Other patients personify the limb with names such
as “Floppy Joe” or “Silly Jimmy”, hate the limb
(misoplegia), or recognize the deficit but show no
concern (anosodiaphoria).
 Anosognosia for hemiplegia - large R hemisphere
strokes; par, front & temp lobes, insula, subcortex
Corpus Callosum and Left
Hemisphere in Delusions
 Act
to disconnect more than connect
 Kosslyn – L hem is categorical
 Callosotomy studies
 The
verbal hemisphere - tends to lie
 Snow
scene R Hem; Chicken claw L Hem
L hand picked shovel, R hand picked chicken
 “I saw a claw and I picked the chicken, and you have to
clean out the chicken shed with a shovel”

 Nude

photo
Oh doctor…you have some machine!
The Hemispheres in Delusions
 Right
lesions disinhibit the left hemisphere;
loss of monitoring of:
 Reality,
self-awareness, emotional familiarity, ego
boundaries
 Disrupts relation between and monitoring psychic,
emotional, and physical self to people, places and even
body parts
 Excess lying & categorical thinking
 Left
hemisphere is the delusional hemisphere.