Similarities in presentation of Dementia of Alzheimer's Type, Vascular Dementia, Frontotemporal Dementia, and Major Depressive Disorder, pose differential diagnosis challenges. The current study identifies specific neuropsychological patterns of scores for Dementia of Alzheimer's Type, Vascular Dementia, Frontotemporal Dementia, and Major Depressive Disorder. Neuropsychological domains directly assessed in the study included: immediate memory, delayed memory, confrontational naming, verbal fluency, attention, concentration, and executive functioning. The results reveal specific neuropsychological comparative profiles for Dementia of Alzheimer's Type, Vascular Dementia, Frontotemporal Dementia, and Major Depressive Disorder. The identification of these profiles will assist in the differential diagnosis of these disorders and aid in patient treatment.

The study of olfaction in neurodegeneration has primarily focused on Alzheimer's disease. Research of olfaction in frontotemporal dementia (FTD) has generally not been empirically studied. The current study compared olfaction in FTD to major depressive disorder (MDD) using the Alberta Smell Test (AST). Independent-samples t test results suggested olfaction in FTD was impaired when compared with participants diagnosed with MDD. The AST Total score (out of 20 trials) significantly predicted the diagnostic group and accounted for 40% of the variance in diagnostic group status with an odds ratio of 20.08. Results suggested that a cutoff of ≤2/20 differentiated FTD from MDD with 94% accuracy (91% sensitivity, 97% specificity) and a cutoff of ≤1/20 differentiated the groups with a 95.5% hit rate (91% sensitivity, 100% specificity). Results confirmed olfactory identification deficits in FTD and suggested that the AST is an effective tool for the demarcation of FTD from MDD. This is especially important due to the potential for significant overlap in the behavioral/emotional phenotype and cognitive deficits between the two disorders when presented with early stages of FTD.

RESULTS failed to show distinctions between groups on pattern of memory impairment when using discrepancy comparisons. However, an analysis examining percentage retention scores revealed better maintenance of non-contextual visual information over time in SSD. Findings may suggest deficits in immediate encoding rather than memory decay for some types of memory ability among geriatric SSD. Our failure to document group differences when using discrepancy comparisons may be attributable to relative similarity in pattern between groups or the limited sensitivity of this technique.

Findings lend support to the specificity of cognitive processes in SSD, even when accounting for processes common to the theoretically similar FTD. SSD showed a distinct pattern of spared ability which supports clinical utilization of discrepant measures of premorbid intellectual estimation for SSD.