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New Criminal Behavior May Signal Frontotemporal Dementia
Medscape Medical News
January 05, 2015

New criminal behaviors, such as theft, sexual advances, and violence, can be the first manifestation of dementia, and the frequency and type of such behaviors may provide clues to a specific underlying neurodegenerative disorder, according to a new study.

The study showed that new criminal activity is associated with behavioral variant frontotemporal dementia (bvFTD) and semantic variant primary progressive aphasia (svPPA), which can affect impulsiveness and inhibition. However, such behaviors are much less likely among patients with Alzheimer's disease (AD).

The study findings suggest that neuropsychological testing to rule out involvement of a neurodegenerative disease might be beneficial for older first-time offenders, said study author Georges Naasan, MD, assistant professor, neurology, and clinical director, Memory and Aging Center, University of California at San Francisco (UCSF).

Previous studies had similar findings but were much smaller, Dr Naasan told Medscape Medical News. "We were confirming what we knew before, but also adding a sort of comparative flavor as to the differences between people with frontal types of dementia and other types of dementia."

While bvFTD and svPPA affect the frontotemporal circuit, and the inherited Huntington disease (HD) affects the frontal-subcortical circuit, AD primarily affects the hippocampal and posterior parietal-temporal circuits.

The study is published online January 5 in JAMA Neurology.

Driving Violations, Theft
Researchers reviewed the medical records of 2397 patients who were seen at the UCSF Memory and Aging Center between 1999 and 2012. A retrospective study design allowed investigators to analyze a very large number of patients with rare disorders who present infrequently.

To identify criminal behavior, they screened an electronic database containing 13,477 patient notes for key words such as "arrest," "court," "embezzle," and "jail." From this process, they identified 204 patients as having demonstrated criminal behavior during their illness.

The major diagnostic groups were bvFTD (n = 64), svPPA (n = 24), AD (n = 42), and HD (n = 6). Other diagnostic groups, including corticobasal syndrome, mild cognitive impairment, vascular dementia, and progressive supranuclear palsy, were not included in the analysis.

Researchers stratified the criminal behaviors into the following categories: driving under the influence, hit and run, traffic violations, speeding, insubordination toward legal authorities, sexual advances, loitering, public urination, theft, trespassing (volitional vs wandering), and violence. They included only criminal behaviors that occurred during the patient's illness.

Calculating the frequency of criminal behavior, researchers found that the by FTD group had the highest percentage of criminal behaviors (37.4%), followed by svPPA (27.0%) and HD (20.0%). Patients with AD were among the least likely to commit crimes (7.7%; P < .001).

The odds ratio for criminal behavior in patients with FTD compared with those with AD was 7.2 (P < .001), and in patients with svPPA compared with those with AD, it was 4.4 (P < .001). Criminal behavior as a first presentation was found in 14.0% of patients with bvFTD, 7.8% of patients with svPPA, and 2.0% of patients with AD (P < .001).

As for the type of crime, patients with bvFTD were significantly more likely to commit all crimes except hit-and-run accidents. About 6.4% of those with bvFTD exhibited violence (about half verbal and half physical) during their illness compared with 3.4% of patients with svPPA and 2.0% of patients with AD (P = .30 and .003, respectively).

Sexual Advances
In patients with bvFTD, sexual advances, theft, and public urination were common manifestations of their illness, occurring as the presenting symptom in 14.0% of these persons. According to the authors, changes to the ability to avoid punishment are characteristic of anterior insular and lateral orbital frontal injury, areas that are particularly vulnerable to bvFTD.

"People with frontotemporal dementia don't have a lot of social inhibitions, and they really try to seek rewards, or things that make them feel happy," commented Dr Naasan. "So they engage in trespassing because they enjoy being in a particular place, or they steal things because, in their minds, they're not stealing."

For the svPPA group, theft and traffic violations accounted for almost all pathologic behaviors. The authors noted that the anatomic substrate of svPPA is bilateral anterior temporal with some involvement of the orbitofrontal regions, and that anterior temporal degeneration, combined with disinhibition due to orbitofrontal dysfunction, likely accounts for the propensity to steal.

Some patients with svPPA have an intense visual preoccupation and a compulsive attraction to small objects. They may have lost the capacity to know the meaning of these objects, so they may be holding a cup in their hand but have no idea what it is, said Dr Naasan.

Their propensity to steal is due in part to compulsiveness, added Dr Naasan. "They can't control the impulse. They see a shiny object that they like; they have no idea of what it is, but they take it anyway."

Patients with HD also display impulsiveness. Crimes committed by such participants in the study included traffic violations, trespassing, and violence.

"People with HD do a lot of things based on impulsive anger," noted Dr Naasan. "They are more likely to be the person who, stuck in traffic, doesn't want to wait anymore and so charges ahead and hits someone in front of them. They're impulsive and they have a lot of mood problems so the combination of the two sort of leads to their behavior."

While bvFTD and svPPA affect the front part of the brain, and so affect social behavior, AD affects the back part of the brain, or memory. "There is some evidence to suggest that Alzheimer's patients are even more social than other people," said Dr Naasan. "Since the back part of their brain is sort of turned off in a way, or is not working, the front part is taking over and it's over compensating. So these patients can become overly nice or socially appropriate."

Theft, public urination, and sexually inappropriate behavior were uncommon in patients with AD. When behavioral dysfunction did occur in this group, it emerged in later stages of the disease and often stemmed from cognitive dysfunction. The most frequent charges were traffic violations. When AD patients trespassed, it was due to wandering.

All patients who urinated in public were men. According to Dr Naasan, inappropriate behavior by women included things like approaching and hugging strangers or inappropriate sexual behavior, although men were more likely than women to make sexual advances toward others.

In the subgroup of deceased individuals who were autopsied (n = 31), there was a 93% concordance between the clinical and neuropathologic diagnoses, said the authors.

The study results provide evidence that older patients who commit crimes that deviate from their typical personality should be screened for an underlying neurodegenerative disorder, said Dr Naasan.

"When you've gone through life for 50 years and haven't done anything and then, all of a sudden, you're involved in a case of sexual abuse or whatever, I think that at some point someone in the system should wonder [whether] this person needs a medical evaluation rather than putting him in prison, and then years later when he progresses, discovering that this was, in fact, a dementia."

The study couldn't determine how many offenders in custody have a neurodegenerative disease that may have led to their criminal behavior. "One of limitations of this study is that we are coming at this from a cohort of people who presented to clinic," said Dr Naasan. "We didn't have data from the judicial system."

Right From Wrong
Complicating the issue is that technically, patients with FTD don't generally meet the criteria for not being criminally responsible for their actions.

"They would probably answer correctly asked if this act is wrong or this other act is right, but that doesn't mean that they have the brain networks that allow them to behave accordingly," said Dr Naasan. "So it's tricky because cognitively, they can tell, but behavior-wise, they may not be able to control their actions."

Approached to comment, Christopher M. Filley, MD, director, Behavioral Neurology Section and professor, neurology and psychiatry, University of Colorado School of Medicine, Denver, called the new study "impressive."

"The finding that bvFTD patients are most at risk is neurobiologically plausible and consistent with the experience of neurologists who see patients with these diseases," said Dr Filley, who has researched the neurobiology of aggression and violence.

As well, the finding that people with AD are far less likely to display criminal behavior is an "interesting observation," said Dr Filley.

He also agreed that the findings could affect the judicial system. "This work has important implications, not only for patient care but also for the legal system, as it encounters patients with neurodegenerative diseases affecting frontal systems," he said.

The authors have disclosed no relevant financial relationships.

JAMA Neurol. Published online January 5, 2015. Abstract
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