People with frontotemporal dementia have a significantly higher risk of committing criminal or socially inappropriate behavior, as shown by Swedish research.
Furthermore, the appearance of criminal behavior in a previously law-abiding person, the researchers suggest, could serve as a diagnostic warning signal that dementia is developing.
Frontotemporal dementia (FTD) is difficult to identify because it manifests itself in a range of symptoms similar to those of Alzheimer's disease (AD) and also in unrelated conditions, such as stroke or depression.
As with many neurodegenerative diseases, the conclusive diagnosis can only be made during the autopsy.
This was the approach used by researchers led by Madeleine Liljegren of the Swedish Lund University.
She and colleagues examined the pathologies of 220 people who had been diagnosed, post mortem, with FTD or AD, and compared the results with their criminal and behavioral stories. The cohort included 119 cases of FTD and 101 cases of AD.
Of the group, 58% were female, the average age of onset of the disease was 63 years, the average age at death was 72 years and the average time spent with both diseases was nine years (although it varied from one year to 28).
Instances of criminal behavior were found in 65 of the 220 – most of them, 50, among FTD sufferers. Furthermore, approximately 89% of the criminally active FTD subgroup had committed more than one criminal act. The repetition rate in AD criminals was significantly lower at 53%.
The difference between cases of socially inappropriate behavior was also significant. It was recorded in the registers of 89 members of the FTD group and 57 members of the AD group.
"These results suggest that criminal and socially inappropriate behavior may be more widespread and that criminal behavior may be more recurrent in patients with FTD than in those with AD," the authors conclude in a paper published in JAMA Network Open.
"These results can help with the clinical diagnostic process."