Distinctions between the dementia in amyotrophic lateral sclerosis with frontotemporal dementia and the dementia of Alzheimer's disease

Abstract

The clinical entity of Amyotrophic Lateral Sclerosis with Frontotemporal Dementia (ALS-FTD) has only recently been recognized as an important neurodegenerative disease. As in isolated FTD, the behavioral and personality changes in ALS-FTD might be more characteristic than its cognitive changes. We aimed to characterize the behavioral and cognitive deficits in ALS-FTD, and contrast this profile with that of the most common form of dementia, AD, to assist ALS clinicians in recognizing the syndrome early in its course. Specifically, we hypothesized that a modified version of the Frontal Behavioral Inventory (FBI-mod), a brief questionnaire self-administered by a caregiver, along with just a few cognitive tests, would be clinically useful in distinguishing the dementia in ALS-FTD from the dementia of AD. We administered a battery of neuropsychological tests to 15 patients who met established criteria for Amyotrophic Lateral Sclerosis with Frontotemporal Dementia and to 30 patients who met established criteria for probable Alzheimer's disease. The FBI-mod was completed by caregivers. We found that the FBI-mod, age-corrected Z scores for the Mini-Mental State Examination (MMSE), a test of delayed recall, and a word fluency measure together discriminated between ALS-FTD and AD. ALS-FTD was characterized by more abnormal FBI scores and poor word fluency, in the presence of relatively normal overall cognitive status (MMSE) and/or delayed recall.