Suicidal Behavior in Dementia: A Special Risk in Semantic Dementia

Background: Some studies report a low suicide risk in general dementia and in Alzheimer's disease (AD). Objective: To evaluate suicidal behavior among patients with semantic dementia (SD), a disorder that impairs semantic knowledge. Methods: We reviewed the presence of active suicidal behavior and related factors among 25 patients with SD compared to 111 age-matched patients with early-onset AD. Results: In all, 5 (20%) patients with SD had suicidal behavior (2 successfully killed themselves) compared to 1 (0.9%) with AD (P < .001). There was significantly more depression and greater premorbid history of suicidal behavior among the patients with SD compared to those with AD. Among the patients with SD, those with suicidal behavior, compared to those without, had more depression and greater insight into their deficits. Conclusions: Patients with SD are at special risk of committing suicide, particularly if they have depression and preserved insight. Possible mechanisms include an impaired sense of semantic competence with increased impulsivity.