Differential Longitudinal Decline on the Mini-Mental State Examination in Frontotemporal Lobar Degeneration and Alzheimer Disease

OBJECTIVE:To examine how phenotype affects longitudinal decline on the Mini-Mental State Examination (MMSE) in patients with frontotemporal lobar degeneration (FTLD) and Alzheimer disease (AD). BACKGROUND:The MMSE is the most commonly administered assessment for dementia severity; however, the effects of phenotype on longitudinal MMSE performance in FTLD and AD have not been extensively studied. METHODS:Data from 185 patients diagnosed with AD (n=106) and 3 FTLD (n=79) phenotypes [behavioral variant frontotemporal dementia (bvFTD), nonfluent agrammatic variant of primary progressive aphasia (nfaPPA), and semantic variant PPA (svPPA)] were collected for up to 52 months since initial evaluation. RESULTS:Differential rates of decline were noted in that MMSE scores declined more precipitously for AD and svPPA compared with bvFTD and nfaPPA patients (P=0.001). The absolute 4-year MMSE decline given median baseline MMSE for bvFTD [14.67; 95% confidence interval (CI), 14.63-14.71] and nfaPPA (11.02; 95% CI, 10.98-11.06) were lower than svPPA (22.32; 95% CI, 22.29-22.34) or AD (22.24; 95% CI, 22.22-22.26). CONCLUSIONS:These data suggest that within-group AD and FTLD phenotypes present distinct patterns of longitudinal decline on the MMSE. MMSE may not be adequately sensitive to track disease progression in some phenotypes of FTLD.