Objective: To evaluate the sense of “humanness” in frontotemporal dementia (FTD) patients with right hemispheric involvement.
Background: Early in the course, FTD is often asymmetric, and those with predominant right frontotemporal disease have disproportionate disturbances in social behavior and empathy. A disruption in a sense of humanness may underlie these behavioral disturbances.
Method: Sixteen patients with asymmetric FTD on functional neuroimaging underwent recognition tests of facial masking, human-animal morphing, and facial distortion. Additional tests evaluated facial discrimination and the recognition of famous faces, facial emotions, and animate–inanimate differences.
Results: On the distorted and morphed face tasks, 8 FTD patients with predominant right hemisphere involvement were significantly more likely to call morphed and distorted faces “human” as compared with both 8 FTD patients with predominant left hemisphere involvement and normal controls. The FTD groups did not differ on thresholds for recognizing masked faces or on other face recognition measures.
Conclusions: In FTD, right hemispheric involvement may alter the threshold for judging someone as human independent of the recognition of faces or facial affect. These results suggest that a specific sense of humanness facilitates a person recognition network in the right frontotemporal region of the brain.
David Geffen School of Medicine at UCLA, The University of California at Los Angeles, Los Angeles, California
Received October 13, 2003; revised May 3, 2004;
accepted May 26, 2004.
Reprints: M. F. Mendez, Neurobehavior Unit (116AF), VA Greater Los Angeles Healthcare, 11301 Wilshire Blvd, Los Angeles, CA 90073 (e-mail Mmendez@UCLA.edu).