Criminal Behavior Could Signal Early Stages of Dementia

New findings from the Max Planck Institute for Human Cognitive and Brain Sciences suggest that the emergence of criminal behavior in middle age may indicate the early onset of a neurodegenerative disorder. The results, drawn from a systematic meta-analysis of more than 230,000 individuals, highlight the potential for dementia-related conditions to alter behavior before diagnosis.

The study, led by Matthias Schroeter and Lena Szabo, analyzed 14 studies conducted across the United States, Sweden, Finland, Germany and Japan. The researchers found that criminal risk behavior, such as harassment, property damage, theft and traffic violations, was more common in the early stages of dementia than in the general population. After diagnosis, however, this behavior tended to decline to below-average levels.

“We wanted to raise awareness of this problem with the meta-analysis, which is the first one systematically and quantitatively investigating potential criminal behavior in dementia syndromes. Our hope is that it would help better understanding possible implications of such diseases, identifying possible reasons and encouraging interdisciplinary endeavors to develop coping strategies.”

Dr. Matthias Schroeter.

The findings suggest that violations of social or legal norms could represent early indicators of changes in cognition or personality. In some cases, these behaviors may be the first outward signs of disease, particularly in individuals with no prior history of criminal activity.

Behavior varies by dementia subtype

The researchers reported that criminal risk behavior was most prevalent in behavioral variant frontotemporal dementia, where more than half of individuals studied exhibited such conduct. This was followed by semantic variant primary progressive aphasia (40%) and, to a lesser extent, vascular dementia and Huntington’s disease (15%). The rates were lower for Alzheimer’s disease (10%) and Parkinsonian syndromes (fewer than 10%).

The study also found that men with dementia were more likely to display criminal risk behavior than women. In the case of frontotemporal dementia, male patients were four times more likely than females to engage in such conduct. In Alzheimer’s disease, the gender gap widened further, with men showing a sevenfold increase in prevalence.

“Criminal risk behavior in frontotemporal dementia is most likely caused by the neurodegenerative disease itself. Most of the patients showed criminal risk behavior for the first time in their life and had no previous records of criminal activity.”

Dr. Matthias Schroeter.

Brain changes may underlie loss of behavioral control

In a second study, the researchers investigated structural brain differences associated with this type of behavior. Individuals with dementia who exhibited criminal behavior had greater atrophy in the temporal lobe, a region linked to behavior regulation. The results suggest that criminal risk behavior may stem from disinhibition – a diminished ability to regulate impulses, emotions or social conduct.

Disinhibition can lead to impulsive or inappropriate actions, often without regard for social context or personal consequences. In the context of dementia, this behavior may not reflect intent to commit harm but instead indicate underlying changes in brain function.

Implications for diagnosis and legal considerations

Although the majority of observed offenses were minor, such as indecent behavior or traffic violations, the researchers argue that these actions should not be dismissed. In some cases, they may serve as early warning signs of cognitive impairment, providing an opportunity for earlier diagnosis and intervention.

The findings also raise questions for legal systems that encounter individuals with undiagnosed neurodegenerative conditions. The authors suggest that greater awareness of dementia-related behavioral changes could support more appropriate legal responses and may warrant consideration in sentencing or incarceration policies.

While the researchers caution against overinterpreting the findings, they stress the need for increased awareness among clinicians, legal professionals and the public. They call for interdisciplinary efforts to develop better strategies for identifying and managing behavior that arises as a result of brain disease.

Reference: Schroeter ML, Žuvela M, Szabo L. Criminal minds in dementia: A systematic review and quantitative meta-analysis. Transl Psychiatry. 2025;15(1):324. doi: 10.1038/s41398-025-03523-z

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