There are many illnesses that cause changes in our behavior. Sometimes people suffering from serious neurodegenerative diseases such as frontotemporal dementia and Alzheimer's disease commit a 'crime'. Their disease may be of a severity that means that the person is not responsible for their actions or that they are sufficiently incapacitated to require medical treatments rather than punishment. Our legal systems, rightly, spend a lot of money, time and intellectual angst trying to meet the needs of this group.
Diseases and conditions of the brain that cause deterioration over time can include many types of dementia, head injuries, tumors, infections such as encephalitis, toxic conditions that result from chronic kidney and liver disease. Whatever the cause, these diseases result in brain damage, loss of cells and brain shrinkage. This damage then affects judgement, how we process information or emotions, and our ability to function in everyday life. The resultant changes in behavior vary from person to person. Overall they do, as the damage progresses, lead to antisocial, disinhibited and sometimes even dangerous behavior. But are acts such as violence, sexual disihibition or stealing actually criminal?
A recent study by researchers at Lund University in Sweden and from the University of California looked at the medical records of 2937 people attending California's Memory and Aging Center between1999 and 2012.
Five hundred and forty five patients had Alzheimer's disease (AD), 171 had behavioral variant of frontotemporal dementia (bvFTD) with major personality changes, 89 patients were diagnosed with semantic variant of primary progressive aphasia (language declines) and 30 with Huntingtondisease (an inherited disease).
The researchers showed 2,397 patients 204 (8.5 percent) had a history of criminal behavior that emerged during their illness. Of the patients who exhibited criminal behavior 42 of 545 patients (7.7 percent) had AD, 64 of 171 patients (37.4 percent) with bvFTD, 24 of 89 patients (27 percent) with semantic variant of primary progressive aphasia, and six of 30 patients (20 percent) with Huntington disease.
Common criminal behaviors in the bvFTD group, which had the highest percentage of patients with documented criminal behaviors, were theft, traffic violations, sexual advances, trespassing and public urination. Traffic violations were commonly committed by AD patients and were often related to memory loss. All the patients who urinated in public were men. Men were also more likely than women to make sexual advances (15.2% vs. 5.1%).
These statistics are interesting but may not be quite as simple to interpret at first glance. One persons aggression or violence is another's rude or overbearing expression of frustration. Mediation or supportive agencies may change attitudes and therefore reporting of incidents. That said, as someone who worked in healthcare and in forensic psychiatry, any studies that help us try to understand how disease processes affect behavior is welcome. It can provide better, more thoughtful health services to this group of patients and perhaps prevent casting law abiding citizens into criminals as a result of behavior due exclusively to dysfunctional mental processes out of their control.
Cogn Behav Neurol. 2013 Jun;26(2):73-7. doi: 10.1097/WNN.0b013e31829cff11.
Guilty by suspicion? Criminal behavior in frontotemporal lobar degeneration.
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