A case of schizophrenia with Capgras delusion responded to donepezil

Dear Editor,

Capgras syndrome (also called Capgras delusion) can be defined as a delusion when someone believes that the psychological entity of others is different though they are externally the same (delusion of doubles).[1] Such delusions have been reported in schizophrenia and other psychiatric illnesses.[2] Here, we bring up an unusual case where such delusions in a patient with schizophrenia has responded to an acetylcholinesterase inhibitor in the form of donepezil.

A 28-year-old unmarried male presented to us with commanding auditory hallucinations, bizarre delusions that an unknown female is residing in his head and controlling him, along with thought insertion and broadcasting, and urinating and spitting in his room. Duration of illness was for past 7 months and insidious in onset. He was diagnosed with schizophrenia according to the Diagnostic and Statistical Manual of Mental Disorders (DSM 5).[3] Positive and Negative Syndrome Rating Criteria (PANSS) had a score of 42 on positive symptoms scale. On the third day of his illness, he claimed that his mother was being replaced by an impostor every evening and became violent towards her. Haloperidol was started at dosage of 10 mg per day and titrated to 20 mg daily over a week along with trihexyphenidyl 6 mg. 10 modified electroconvulsive therapy (ECT) sessions were administered after all the relevant investigations. Three weeks after starting the treatment, majority of the symptoms reduced. PANSS came as 13 in positive symptoms scale, but Capgras delusion persisted in the form of the mother being replaced by an impostor. The patient was discharged on haloperidol 20 mg and trihexyphenidyl 6 mg. During the next follow-up visits, one and two months following discharge, Capgras delusion was the only symptom he had. Mini Mental State Examination (MMSE) score was 28. Olanzapine in dosage of 10 mg was added and uptitrated to 20 mg over two weeks with no response. The patient was then started on donepezil 10 mg and increased to 23.5 mg over a month. Capgras delusions disappeared in the follow-up visit 45 days following the start of donepezil, and his aggressive behavior towards his mother also subsided. Olanzapine was stopped over a week and he was well-maintained on haloperidol and donepezil. As both haloperidol and olanzapine failed to treat Capgras delusion, we can conclude that donepezil was the drug that resulted in the cure of the same.

Visuo-amygdaloid pathway dysfunction has been postulated for visual misidentification in schizophrenia and dementia.[4,5] Brain cholinergic dysfunction leads to visual hallucinations and Capgras-like visual decomposition of faces in Lewy Body Dementia.[5] In our case, as Capgras delusion was the only delusion that persisted after treatment, we considered donepezil over any other antipsychotic. Cholinesterase inhibitors have shown to be useful to target the visual phenomena with superior safety when compared to neuroleptics.[5] Reports of Capgras syndrome in dementia responding to acetylcholinesterase inhibitor is handful in literature.[4,5]

To our knowledge this is a rare scenario where the delusion has responded successfully to donepezil in the context of schizophrenia.

On encountering such a case in schizophrenia or any other psychotic or neurotic illness, use of donepezil or any other acetylcholinesterase inhibitor should be considered.

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Ethical concerns

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Conflicts of interest

There are no conflicts of interest.