Frontal-executive Versus Posterior-perceptual Mental Status Deficits in Early-onset Dementias

Background: Compared to late-onset dementias, early-onset dementias (EODs) may have greater focal cognitive involvement with differences in frontal-executive compared to posterior-perceptual deficits. Objective: This study evaluated whether mental status screening based on this frontal-posterior axis can distinguish EODs. Methods: Twenty-three patients each with early-onset Alzheimer's disease (eAD), frontotemporal dementia (FTD), or subcortical ischemic vascular disease (SIVD), and 20 normal controls underwent the Frontal Assessment Battery (FAB) and the Perceptual Assessment Battery (PAB). Results: Compared to controls, SIVD and FTD groups were impaired on the FAB whereas eAD and SIVD groups were impaired on the PAB. The FAB/PAB ratio further differentiated the groups (F(3,85) = 26.49, P < .001). For sensitivities and specificities of 93%, a cut-off score of 1.25 on the FAB/PAB distinguished eAD, and a cut-off of 0.83 distinguishing FTD. Conclusion: Although preliminary, this study indicates that mental status screening based on frontal versus posterior cortical functions may help clinicians diagnose EODs.