Researchers have investigated the prevalence of criminal behavior in patients with diagnosed neurodegenerative disorders. They found that certain forms of disease are more likely to increase risk of committing criminal acts than others.

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Individuals who care for middle-aged and elderly patients need to be vigilant in the diagnosis of degenerative conditions, according to the authors of the study.

The study, published online in JAMA Neurology, also states that criminal acts such as theft, traffic violations, and public urination are also more likely to be early manifestations of such disorders.

Neurodegenerative diseases can cause dementia – a progressive decline in cognitive functioning that can interfere heavily with daily routines and social interactions.

In particular, neurodegenerative diseases such as Alzheimer’s disease and behavioral variant of frontotemporal dementia (bvFTD) can prevent the areas of the brain involved with decision making, emotional processing, judgment, self-awareness, sexual behavior and violence from functioning properly.

The researchers note that dementia can lead to people with no history of antisocial activities exhibiting behavior that is antisocial and often could be classified as criminal by law and society. Despite this pre-existing association, they report that few studies have attempted to systematically assess antisocial behavior among people with dementing neurodegenerative disorders.

For the study, researchers from Lund University, Sweden, and the University of California, San Francisco (UCSF), reviewed the medical records of 2,397 patients. The patients all attended the UCSF Memory and Aging Center between 1999 and 2012.

The following diagnosed neurodegenerative disorders among others were observed in the assessed patients:

  • Alzheimer’s disease – 545 patients
  • bvFTD – 171 patients
  • Semantic variant of primary progressive aphasia (svPPA) – 89 patients
  • Huntington disease – 30 patients.

Frequency of criminal behavior among the patients was assessed by screening for specific keywords identifying criminal behavior among 13,477 patient notes.

Criminal behavior was defined by the study as “acts that violate the law as well as those that deviate from social decorum and could potentially lead to legal ramifications,” with keywords decided upon by two neurologists: Dr. Georges Naasan and Dr. David C. Perry.

The review showed a history of criminal behavior in 204 (8.5%) of the patients that emerged during their illnesses. In particular, the following percentages of patients were found to have documented criminal behaviors:

  • Alzheimer’s disease – 7.7%
  • bvFTD – 37.4%
  • svPPA – 27%
  • Huntington disease – 20%.

Types of criminal behavior observed most frequently varied between diseases and patient gender. Patients diagnosed with bvFTD were most likely to have acts of theft, traffic violations, sexual advances, trespassing and public urination documented. In general, traffic violations were most frequently committed by Alzheimer’s disease patients, which were commonly related to memory loss.

Every case of public urination involved male patients, and men were significantly more likely to make inappropriate sexual advances, with the likelihood of 15.2% (men) compared with 5.1% (women).

“Our study shows that new criminal behaviors emerge in association with specific neurodegenerative diseases but not with others,” write the authors. They note that new criminal behaviors are far more prevalent in association with disorders affecting the frontotemporal or frontal-subcortical circuits of the brain.

The study has a number of limiting factors. Patients needing to visit the Memory and Aging Center may have been more likely to have behavioral problems than the general population. Confining the review solely to medical records also meant that the researchers may have missed out on important details regarding the circumstances surrounding criminal behavior.

As a result, the authors acknowledge that prospective studies designed to specifically evaluate criminality will need to be conducted in the future.

Despite these limitations, they believe their findings emphasize the importance of vigilance among carers for patients with degenerative conditions that begin to affect their normal behaviors, particularly if the patients find themselves within legal settings.

“Judicial evaluations for such patients will require different criteria than the classical insanity defense,” conclude the authors, “and neurodegenerative diseases, including bvFTD, should be treated differently by the legal system, such as obtaining a neurologic evaluation when suspected and channeling to palliative and medical institutions.”

Recently, Medical News Today reported on a study claiming to have identified a potential drug target for frontotemporal dementia.