Late-Onset Sex Offending and the Assessment of Behavioral Variant Frontotemporal Dementia (bvFTD)

Behavioral variant frontotemporal dementia (bvFTD) is a common neuropsychiatric disorder, which is often missed or misdiagnosed by both neurologists and psychiatrists as a cause of emotional and behavioral problems. Inappropriate emotional responses and maladaptive behavior, including criminal behaviors, may be the first obvious expression of bvFTD caused by altered moral feelings, loss of empathy, disinhibition, and compulsive behavior. New onset sex offenses, including indecent exposure, sexually inappropriate comments, and unwanted sexual advances have been documented in early bvFTD. These behaviors may escalate with progressive disease and lead to harsh penalties. The presence of inappropriate sexual behaviors in older individuals with no prior history should raise concern about the presence of bvFTD in forensic examinations. In addition to the forensic examination, diagnostic evaluation requires psychological testing (including tests of social and affective cognition) and imaging studies. In sex offenders, a diagnosis of bvFTD has significant implications for risk assessments, requirements regarding supervision and management, and as evidence for mitigation. In this article, we review the neuropsychiatry of bvFTD, how the pathophysiology may contribute to sex offenses, and important psycholegal considerations for the forensic psychiatrist when evaluating bvFTD.