Cognitive decline in the behavioral variant of frontotemporal dementia

Background: Only a small number of studies on the natural disease course in behavioral variant frontotemporal dementia (bvFTD) have been conducted. This is surprising because knowledge about the progression of symptoms is a precondition for the design of clinical drug trials. Methods: The aim of the present study was to examine the cognitive decline of 20 patients with mild bvFTD over one year using the Consortium to Establish a Registry for Alzheimer's Disease-Neuropsychological Assessment Battery (CERAD-NAB). Results: Within an average follow-up interval of 13 months, patient scores declined significantly in the Mini-mental-State-Examination (MMSE) and the CERAD-NAB subtests of naming, verbal and nonverbal memory. No significant changes were found in the CERAD-NAB subtests of category fluency, recognition, and visuoconstruction. The average annualized decline on the MMSE was 4.0 ± 4.9 points. Ceiling effects were detected in Figures Copy, Word List Recognition and Modified Boston Naming Test. Though the included patient group was rather homogeneous regarding severity of dementia, the cognitive changes were very heterogeneous. Conclusion: Given the heterogeneity of cognitive decline, the design of a test battery for clinical trials in FTD will be challenging. A cognitive battery should definitely include the MMSE, Word List Learning and Word List Delayed Recall.