Differentiating the frontal variant of Alzheimer's disease

Abstract

Individuals with a clinical diagnosis of Alzheimer's disease (AD) may have prominent features of executive dysfunction and language impairment as well as behavioral abnormalities early in the disease ('high frontality'). When this occurs differentiation from frontotemporal dementia (FTD) is difficult. It is hypothesized that AD patients with high frontality may have clinical and pathological features that distinguish them from less frontal AD patients. In a well-characterized cohort of people with cognitive impairment, we used the Frontal Behavioral Inventory (FBI) in an attempt to identify AD patients with prominent frontal features (high-FBI AD) and distinguish them from the remainder of AD patients (low-FBI AD). The 18 high-FBI AD patients were compared with the 26 FTD patients who had an FBI performed and the 53 other low FBI AD patients. The individual FBI items did not differ significantly between the FTD and the high-FBI AD patients, and the high FBI AD patients were more like the FTD patients than the other AD patients with respect to presence of a family history of AD, proportion with homozygous apolipoprotein E(4) status, disability as measured by the Disability Assessment for Dementia (DAD) Scale and the Functional Rating Scale (FRS) and neuropsychiatric impairment as measured by the Neuropsychiatric Inventory (NPI). Memory symptom duration was similar in the high FBI AD group compared to the low FBI AD group. There is a subgroup of AD patients with high frontality that can be clinically distinguished from the remainder of AD patients but which requires pathological verification.