Semantic knowledge of social norms in frontotemporal dementia patients with either predominant frontal or temporal lobe atrophy.

OBJECTIVE: Little is known about the relative contribution of frontal and anterior temporal lobes in semantic knowledge of social norms in frontotemporal dementia (FTD). Therefore, this study examined performance of FTD patients with either frontal (F-FTD, left temporal (LT-FTD) or bitemporal lobe atrophy (BT-FTD) on the Social Norms Questionnaire (SNQ) and explored what accounts for the variance in the SNQ-break norm subscale (i.e., endorsement of inappropriate behaviors).

METHODS: Using data from the National Alzheimer's Coordinating Center (NACC), groups were matched for age and education and included (a) 24 F-FTD patients, (b) 15 LT-FTD patients, (c) 17 BT-FTD patients, and (d) 188 older controls with normal cognition (NC).

RESULTS: The BT-FTD group had significantly higher SNQ break norm score than F-FTD and NC groups with a medium effect size, which was also positively associated with the severity personality changes in the real world. Interestingly, the F-FTD and LT-FTD groups performed similarly to the NC group. Regression analysis showed that approximately 21.2% of the variance in SNQ break norms subscale score performance was explained by performance on verb naming.

CONCLUSIONS: Social inappropriateness in FTD may partially arise from a deficit in knowledge of normative behavior.