Clinical Characteristics and Possible Mechanisms Underlying Behavioral and Personality Changes in Ftdp-17

Although the clinical and neuroanatomical characteristics of behavioral and personality changes have been well-defined in frontotemporal dementia syndromes, relatively little is known about the behavioral and personality changes in frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17). Thus, the aim of this study was to longitudinally characterize the behavioral and personality abnormalities associated with FTDP-17. We examined three patients with a clinical diagnosis of FTDP-17 confirmed by genetic testing. In all three patients the P301L MAPT mutation was detected. All patients underwent neuroimaging (MRI and SPECT). Behavior and personality changes were assessed longitudinally with the Blessed Dementia Rating Scale, the Frontal Behavioral Inventory and/or the Neuropsychiatric Inventory. All three patients demonstrated marked and progressive changes in behavior and personality, as revealed by clinical observation and longitudinal assessment. These abnormalities included mainly disinhibition, indiffe rence, and apathy, as well as compulsive-like and utilization behavior. Nonetheless, as the disease progressed, negative symptoms dominated the clinical presentation of all cases. The common behavioral and personality abnormalities in FTDP-17 with MAPT seem to overlap with the behavioral variant FTD. Also, early behavioral and personality changes in FTDP-17 with MAPT are likely associated with the initial locus of neurodegeneration, and may represent an effect of the disease-related dynamic imbalance between the mutually inhibitory interand intrahemispheric processes, which may also possibly account for symptom change as the disease progresses, eventually resulting in an unified behavioral profile of negative symptoms.