Huntington’s and Alzheimer’s are neurodegenerative diseases that sometimes wreck the brain structures required for sound judgment and self-awareness. Because of this, law-abiding citizens who develop these disorders may stray into the danger zone, a new study finds. While no one would describe them as leading a life of crime exactly, patients may begin to behave as common criminals, stealing, trespassing, and urinating in public as they wish.


Physical illness often transforms people in powerful ways; how many survivors of cancer, for instance, positively change their lives as a result of their ordeal? Neurological sicknesses, which may damage structures and pathways in the brain, also may inspire change, though sometimes in unpredictable and far less attractive ways. Consider, for example, a 2007 case study of a Huntington's disease patient reported in the Journal of Forensic Research. This female patient developed amorous feelings for her therapist and soon began a stalking campaign, which included unwelcome gifts, persistent phone calls, and eventually threats. Even after the therapist filed a restraining order, the patient continued to harass her. Doctors involved in the case considered the possibility that the patient’s behavior might actually be a strange symptom of her inherited disease — Huntington’s disorder, which often leads to personality changes, including increased aggression and hostility. After treatment with an antidepressant plus an antipsychotic, the patient’s feeling for her therapist cooled, leading her doctors to suspect the stalking was an expression of her disease.

For the current study, a team of researchers led by Dr. Madeleine Liljegren of Lund University and Dr. Georges Naasan of UC San Francisco investigated the frequency and type of criminal behavior among patients diagnosed with some kind of dementia disorder. In particular, they reviewed and examined the medical records of 2,397 patients who were seen at UC San Francisco’s Memory and Aging Center between 1999 and 2012. Of these patients, 545 had Alzheimer’s, 171 had frontotemporal dementia (causing personality changes), 89 had a variation of primary progressive aphasia (causing language declines), and 30 had Huntington’s.

What did they find? About 8.5 percent (204 of the patients) began to flirt with the forbidden only after they became ill. Among the newborn criminals, 37.4 percent had been diagnosed with frontotemporal dementia, 27 percent had a semantic variant of primary progressive aphasia, 20 percent had Huntington’s, and 7.7 percent had Alzheimer’s.

All the patients who began to urinate in public were men. (Surprise!) Meanwhile guys (15.2 percent) were more likely to make sexual advances, though the ladies (5.1 percent) logged their own share of inappropriate sexual conduct.

Among the most fascinating of the reported crime sprees: one woman started emptying bags of trash from her moving car in order to watch each piece bounce on the open road unraveling behind her. Another woman took to shoplifting, pilfering money from strangers’ pocketbooks, and filling plastic bags with stolen sweets and candy at the local drugstore. The Alzheimer’s patients were the least exciting criminals; they tended to commit traffic violations, usually related to their memory loss.

“These individuals should be treated differently by the law,” the authors wrote in their conclusion. “Judicial evaluations of criminality in the demented individual might require different criteria than the classic ‘insanity defense’ used in the American legal system.”

Source: Liljegren M, Naasan G, Temlett J, et al.Criminal Behavior in Frontotemporal Dementia and Alzheimer Disease. JAMA Neurology. 2015.