Mental illness, violence and delusional misidentifications: The role of Capgras' syndrome in matricide

Introduction: Although important to cognitive neuropsychiatry and theories of delusions, Capgras delusion has largely been reported in single case studies. Bell et al. (2017) previously deployed computational and clinical case identification on a large-scale medical records database to report a case series of 84 individuals with Capgras delusion. We replicated this approach on a new large-scale medical records database from an alternative provider of public mental health services in London while additionally examining associated instances of aggression, given previous claims that Capgras is a risk factor for violence.Methods: We identified 34 cases of Capgras delusion. Delusion phenomenology, clinical characteristics, and presence of lesions detected by neuroimaging were extracted.Results: Although most cases of Capgras involved misidentification of family members or partners, a notable minority (20.6%) included the misidentification of others. Capgras typically did not present as a monothematic delusion. Few cases had identifiable lesions with no evidence of a preponderance of right-hemisphere damage. There was no evidence of physical violence associated with Capgras delusion.Conclusions: The findings closely replicate Bell et al. (2017). The majority of Capgras delusion phenomenology is in line with the ‘dual route’ model although a significant minority of cases cannot be explained by this framework.

Matricide is one of the rarest of reported murders and has always been considered one of the most abhorrent crimes. Psychiatric investigations as to why a son might murder his mother yield indications of a high rate of mental illness, primarily psychotic disorders, in perpetrators. In an attempt to gain an in-depth understanding of the role of the mother-son bond in the etiology of matricide by mentally disordered sons, this article presents a qualitative study of nine cases of matricide examined at two Italian Forensic Psychiatry Departments between 2005 and 2010 and retrospective analysis of forensic psychiatry reports on the offenders. Most matricides suffered from psychotic disorders, especially schizophrenia. Nevertheless, not all the perpetrators had psychotic symptoms at the time of the crime. A "pathologic" mother-son bond was found in all cases. However, mental illness is not the only variable related to matricide and, taken alone, is not enough to explain the crime. Several factors in the history of the mother and son need to be probed, especially how their relationship developed over the years. The peculiar dynamics of the mother-son relationship and the unique personalities and life experiences of both subjects are the real key to cases of matricide.

Postpartum psychosis, which rarely presents with Capgras syndrome (delusional misidentification), requires rapid symptom resolution. First-line drugs have important drawbacks, such as delayed onset of clinical response and secretion in breast milk. In this report, we report successful treatment of a treatment-resistant woman presenting with treatment-resistant Capgras syndrome, with onset during postpartum. A 36-year-old woman had presented with Capgras syndrome during postpartum. For more than five years, she believed her son and other family members were substituted by impostors. All adequately administrated treatments were unsuccessful. We suggested electroconvulsive therapy to overcome treatment resistance. After six electroconvulsive therapy sessions, delusions of doubles subsided and other symptoms improved. She was discharged two weeks later with a mood stabilizer and low-dose atypical antipychotic combination and is well at the one-and-a-half-year follow-up. Electroconvulsive therapy followed by a mood stabilizer-antipsychotic drug combination showed rapid, permanent, and effective control of long-standing Capgras syndrome in a young woman.