Criminal behavior more associated with frontotemporal dementia than Alzheimer disease

1. There was a greater association between criminality and behavioral variant frontotemporal dementia (bvFTD) than there was between criminality and Alzheimer disease (AD).

2. Patients with bvFTD were significantly more likely to have criminal behavior as a first presentation of disease. There was also a trend in patients with bvFTD to commit crimes characterized by violence more so than patients with AD.

Evidence Rating Level: 4 (Below Average)

Study Rundown: Neurodegenerative diseases, which encompass Alzheimer disease, Huntington disease, and frontotemporal dementia among others, result in damage of structures responsible for higher intellectual functions. These functions, such as impulse control, logical reasoning, self-awareness and emotional processing, are fundamental to the success of an individual in navigating social mores and, beyond that, laws. As a result, patients without a history of prior arrests may suddenly commit criminal behavior. This study sought to investigate the incidence of criminal behavior in patients with dementing disorders.

Criminal behavior was ultimately detected in 7.7% of patients with AD, 37.4% with bvFTD, 27.0% with semantic variant of primary progressive aphasia, and 20% of those with Huntington disease. A strength of this study was the attention paid to correlating clinical diagnoses with pathologic results, which decreases confounding. Further, the authors made an effort to hypothesize at what point in the disease criminal behaviors manifested. A weakness was that actual criminal records were not available for study. The study suggests that subtleties in the type of criminal behavior exhibited varies between different dementing disorders, and may represent predilection of the diseases to affect certain parts of the brain. However this particular study was underpowered to confirm these suggestions, and further research is warranted.

Click to read the study, published today in JAMA Neurology

Relevant Reading: Neuropsychiatry of frontal lobe dysfunction in violent and criminal behaviour: a critical review

In-Depth [cross-sectional study]: This cross sectional study reviewed records including 13,477 patient notes representing 2,397 patients seen at the UCSF Memory and Aging Center between 1999 and 2012 for keywords representing criminal behavior, decided on by two authors of the paper. A total of 204 patients were identified as having exhibited criminal behaviors, defined as acts violating the law or deviating from social decorum that could lead to legal ramifications. Of these, 31 individuals were deceased and subsequent pathology postmortem analysis was performed with 93% concordance between clinical and pathologic diagnoses.

Criminal behavior was ultimately detected in 7.7% of patients with AD, 37.4% with bvFTD, 27.0% with semantic variant of primary progressive aphasia (svPPA), and 20% of those with Huntington disease. Patients with bvFTD were more likely to have criminal behavior as a first presentation of disease with 14% of patients, compared to 7.8% of patients with svPPA and 2% of patients with AD (P<0.001). In the bvFTD group, 6.4% of the patients exhibited some form of criminality specifically characterized by violence, compared to 3.4% of patients with svPPA and 2.0% of patients with AD (P=0.30 and P=0.003, respectively).

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