Apathy and disinhibition in frontotemporal dementia: Insights into their neural correlates.
BACKGROUND
Aberrant social behavior is a defining symptom of frontotemporal dementia (FTD) and may eventually occur in all syndromes composing the FTD spectrum. Two main behavioral abnormalities have been described: apathy and disinhibition, but their neuroanatomical correlates remain underspecified.


METHODS
Sixty-two patients with a clinical diagnosis of FTD participated in the study. Voxel-based morphometry of MRI data was performed to explore the association between gray matter loss and severity of the two behavioral profiles as measured by the Apathy and Disinhibition subscales of the Frontal Systems Behavior Scale.


RESULTS
Compared with a group of controls, the FTD group showed extensive bilateral atrophy predominantly involving frontal and temporal lobes. Within the FTD group, the severity of apathy correlated with atrophy in the right dorsolateral prefrontal cortex. The severity of disinhibition correlated with atrophy in the right nucleus accumbens, right superior temporal sulcus, and right mediotemporal limbic structures.


CONCLUSIONS
Prefrontal and temporal regions are differentially associated with apathy and disinhibition. Our results support the view that successful execution of complex social behaviors relies on the integration of social knowledge and executive functions, represented in the prefrontal cortex, and reward attribution and emotional processing, represented in mesolimbic structures.
Zamboni
G
G
Cognitive Neuroscience Section, National Institute of Neurological Disorders and Stroke, NIH, Bldg. 10, Room 7D43, MSC 1440, Bethesda, MD 20892-1440, USA. grafmanj@ninds.nih.gov
Huey
E D
ED
Krueger
F
F
Nichelli
P F
PF
Grafman
J
J