Dietary changes, compulsions and sexual behavior in frontotemporal degeneration

The occurrence of weight gain, sweet and carbohydrate craving, hyposexuality, and compulsions in frontal lobe dementia (FLD) compared to Alzheimer's disease (AD) was evaluated. FLD is a progressive dementia with a high rate of misdiagnosis and therefore better diagnostic criteria for FLD are needed. Fourteen patients meeting research criteria for AD were compared to 14 with suspected FLD. All had cerebral perfusion measured with xenon-133 and imaged with HMPAO using brain-dedicated SPECT. The FLD group showed frontotemporal and AD posterior temporoparietal hypoperfusion. The primary caregivers were queried regarding weight gain, sweet/carbohydrate preference, sexual drive, and compulsions. Differences were compared with Fisher's exact test. The following was found in FLD versus AD: Weight gain in FLD patients amounted to 64% (AD 7%), carbohydrate craving was 79% (vs. 0%) and compulsive behavior 64% (vs. 14%). The differences for these symptoms were statistically significant, whereas for the symptoms increased sexual drive (8 vs. 8%) and reduced sexual drive (54 vs. 23%) no significant difference could be found. In FLD the first symptoms were often dietary changes or hyposexuality. Compulsions were more bizarre and severely disabling in FLD than in AD. Dietary changes, hyposexuality, and disabling compulsions are prominent early symptoms in FLD but not AD. The cause of these symptoms may be due to both frontal and subcortical serotonin loss and dysfunction of the anterior temporal lobes.