Criminality and Dementia

Criminal behavior, Alzheimer's disease, and frontotemporal dementia.

Posted Feb 05, 2015

We may not be surprised when an older person with a long history of criminal behavior gets into trouble again. But when a 60-year-old minister who has always been a role model to his community or a 75-year-old aunt who never did anything even vaguely illegal is arrested, we wonder what is going on.

A recent study published in JAMA Neurology by Madeleine Liljegren and colleagues suggests that new, late-onset criminal behaviors may reflect an underlying dementia. Furthermore, these investigators demonstrate that the types of crimes committed vary with the type of dementia.

This study involved a retrospective record review of patients seen at the Memory and Aging Center at the University of California, San Francisco between 1999 and 2012. About 8% of 545 people with Alzheimer’s disease got into legal trouble, often because of trespassing or traffic violations. Such behaviors usually occurred when cognitive symptoms of the dementia were already well established. People with dementia may wander onto private property or drive the wrong way on a highway because they are confused. They may walk out of a store with an item thinking they had already purchased it. Such “criminal” behavior is understandable in the context of the illness. 

Late-onset criminal behaviors involving socially inappropriate actions such as unwanted sexual advances, public urination, and fighting usually do not occur in the context of Alzheimer’s disease. However, such behaviors are common in another type of dementia called behavioral variant frontotemporal dementia (bvFTD). In fact, Liljegren and colleagues reported that over 37% of 171 persons with bvFTD got into legal trouble with socially inappropriate behaviors.

BvFTD typically occurs in people in their 50s and is characterized by a gradual onset of personality changes including impulsive and inappropriate behaviors. Over time, these behaviors become more pronounced. Cognitive changes involving memory, organizational abilities, and language gradually develop, but after, not before, the behavioral changes. Early brain damage in bvFTD involves brain regions that are part of the “emotional salience network.” This network includes regions such as the amygdala and insular cortex, areas known to regulate emotional processing. Alzheimer’s disease initially attacks different areas of the brain related to cognitive processing, memory, and planning (referred to as the “default mode network”). Why these different forms of dementia initially attack specific brain networks remains poorly understood, but it is an area of high scientific and clinical interest.

When a middle-aged or elderly person gets into trouble with the law for the first time in his or her life, psychiatrists may be asked to evaluate the person in order to determine if a neuropsychiatric condition contributed to the criminal behavior. In addition to dementias, other neuropsychiatric disorders that can begin in mid to late life, including bipolar disorder and alcohol abuse, may lead to criminal behaviors. The medical management of conditions such as bvFTD, mania, and alcohol abuse, and the legal management of criminal behaviors committed by persons suffering from these conditions demonstrate the important interaction between medicine and the law.

This column was co-written by Eugene Rubin MD, PhD and Charles Zorumski MD.