Patients with the behavioral variant of
frontotemporal dementia have marked impairment in everyday life, yet little is known about factors underlying this impairment. Moreover, a recently identified subgroup with normal brain imaging has an excellent prognosis (phenocopy cases) and their performance on
activities of daily living (
ADL) tasks is unknown. Eighteen behavioral variant
frontotemporal dementia patients were assessed on 2
ADL measures, the Disability Assessment for
Dementia, a caregiver-based interview, and the Assessment of Motor and Process Skills, a performance-based instrument. Behavior change, global cognition, executive function, and magnetic resonance imaging brain
atrophy were also evaluated. There was no association between the 2
ADL measures. A model combining the Addenbrooke's Cognitive Examination Revised (global cognition) and Frontal Systems Behavior Scale (frontal dysfunction) explained the variance on
ADL performance. A qualitative rating distinguished between pathologic and phenocopy patients better than the performance-based assessment. Degree of frontal dysfunction and overall
dementia determined the level of
ADL impairment. The phenocopy patients were clearly distinguishable when evaluated using a performance-based, and even better with a qualitative rating assessment.