The influence of right frontotemporal dysfunction on social behavior in frontotemporal dementia

Background: Frontotemporal dementia (FTD) is associated with a variety of cognitive and behavioral dysfunctions. Symptoms may be influenced by the relative involvement of the right versus the left hemisphere, with left-sided FTD manifesting language changes and right-sided FTD presenting with aggressive, antisocial, and other socially undesirable behaviors. Objective: To test the hypothesis that right-sided FTD is associated with socially undesirable behavior. Methods: The authors assessed 41 patients with FTD diagnosed by the new research criteria for FTD1 including behavioral, neuropsychologic, and neurologic testing as well as SPECT and MRI. Based on visual inspection of SPECT scans, 12 patients were classified as having predominantly right-sided and 19 patients were classified as having predominantly left-sided FTD. A clinician blinded to the imaging data reviewed medical records to tabulate the frequency of the following socially undesirable behaviors: criminal behavior, aggression, loss of job, alienation from family/friends, financial recklessness, sexually deviant behavior, and abnormal response to spousal crisis. Results: Eleven of 12 right-sided and 2 of 19 left-sided FTD patients had socially undesirable behavior as an early presenting symptom (chi = 23.3, p < 0.001). Conclusion: The authors conclude that right-sided frontotemporal degeneration is associated with socially undesirable behavior. The early presence of socially undesirable behavior in FTD differentiates right-sided from left-sided degeneration. The results highlight the importance of the right hemisphere, especially frontotemporal regions, in the mediation of social behavior. The potential mechanism for these social losses with right-sided disease is discussed.