Homicide and Dementia: A Systematic Review

Background: Homicide by older offenders is rare and devastating. It likely occurs due to a complex interaction of personal, social, and environmental factors. Dementia is a progressive neurological condition which may amplify behavioural disturbances such as aggression. This systematic review aims to evaluate the factors associated with homicide committed by people with dementia in order to inform clinical practice.

Summary: MEDLINE, PsychINFO, Embase, and PubMed databases were searched in accordance with PRISMA guidelines for empirical studies examining the characteristics and circumstances of people with dementia who committed homicides. Data on factors associated with the homicide were extracted and the quality of each study rated using standardized criteria. A total of 499 papers were screened and thirteen studies met the inclusion criteria. Study design included case reports (seven studies), case series (four studies), and two retrospective cohort studies, indicative of low levels of evidence. Sample sizes were 1-70. Study findings were predominantly descriptive. Quality ratings ranged from 50 to 100%. Factors associated with disinhibition such as dysexecutive syndrome, alcohol use, and delirium may predispose to severe impulsive aggression. Psychosis and personality pathology appeared to influence targeted assaults resulting in homicide by people with dementia. Victim vulnerability was also a key element.

Key messages: The current evidence examining risk factors for homicide committed by people with dementia is limited. However, there are common characteristics reported in these descriptive studies including psychiatric factors and cognitive states causing disinhibition. Recommendations for clinical practice include early assessment of older people with dementia and changed behaviours to allow management of comorbidities and reversible risk factors, alongside education, and advice to carers (who may be targets of aggression). Specialized geriatric forensic psychiatry services and care settings should be developed.