Neurology of DelusionsNeurology of Delusions
Orrin DevinskyOrrin Devinsky
DelusionDelusion
Pathological, fixed idea Cannot be overturned by evidence
Not culturally or religious condoned Can be bizarre or non-bizarre Occur in primary psychiatric disorders
(schizophrenia, delusional disorders) and secondary neurological disorders
Delusions in PsychiatryDelusions in Psychiatry
Schizophrenia - often bizarre Influence, persecution/paranoia, self-significance
Psychosis due to mood disorder Delusional disorder - prominent non-bizarre
delusions lasting > 1 month Erotomania Grandiose Jealous Persecutory Somatic Mixed
Delusions in Delusions in Neurological DisordersNeurological Disorders
Generalized Neurological Disorders Neurosyphilis (grandiose) Dementia - Alzheimer’s, Multi-infact, Lewy body
disease Parkinson’s disease Toxic-metabolic Epilepsy – Postictal & interictal
Focal Neurological disorders Stroke Tumor Head trauma Epilepsy – Interictal & postictal
Content Specific Delusions Content Specific Delusions in Neurological Disordersin Neurological Disorders
Delusional misidentification syndromes 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 Content Specific Delusions: Delusions:
Poles of FamiliarityPoles of Familiarity Loss of familiarity
People Capgras Mirror sign
Places 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 Content Specific Delusions: Delusions:
Neuropsychiatric Neuropsychiatric PendulumPendulum
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: Anatomy of Delusions: Bifrontal & Right Bifrontal & Right
HemisphereHemisphere 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 Reduplicative Paramnesia Paramnesia
1903 - first described by Pick as a memory disorder
A place simultaneously exists in two or more physical locations Unfamiliar place (hospital) is in home town
Associated with R hemisphere dysfunction Benson et al 1976 & Ruff & Volpe, 1981. RHDamage BHDamage LHDamage (Feinberg, 1989)
36 (52%) 28 (41%) 5 (7%) <.0001 (7x) With neurological lesions – R frontal or parietal
Capgras’ Patient (’23 & Capgras’ Patient (’23 & ‘24)‘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 Capgras Syndrome & Right HemisphereHemisphere
Hayman & Abrams 1977 & Alexander et al, 1979 Review of literature (Feinberg ,1989)RHDamage BHDamage LHDamage
8 (32%) 16 (62%) 2 (7%) <.06 (4X R>L)
Capgras Syndrome: Capgras Syndrome: MechanismsMechanisms
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 & 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: Capgras and Familiarity: WhyWhy
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 Familiarity & The Temporal LobeTemporal 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 Déjà vu: Familiarity & The Temporal LobeTemporal 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 Familiarity & The Temporal LobeTemporal 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 DementiaCapgras 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 Capgras & Lewy Body Disease?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
HyperfamiliarityHyperfamiliarity
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.
HyperfamiliarityHyperfamiliarity
Seven patients reportedAll had TCS or epilepsyMost with Left hemisphere or bilateral
pathology, usually affecting temporal lobeDéjà 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 Frontal Pathology in Delusions Delusions (Feinberg et al, 2005)(Feinberg et al, 2005)
29 patients with misidentification-reduplication 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 Frontal Pathology in DelusionsDelusions
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: Anosognosia: A Delusional Disorder?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: Anosognosia: A Delusional Disorder?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 Corpus Callosum and Left Hemisphere in Left Hemisphere in
DelusionsDelusions 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 The Hemispheres in DelusionsDelusions
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.
