Differentiating Memory Deficits in bvFTD, AD, and MCI: A Propensity Score and Volumetric Neuroimaging Analysis of Frontal and Medial Temporal Lobe Contributions

This study investigated the relative contributions of medial temporal lobe (MTL) integrity and frontal lobe functions in behavioral variant frontotemporal dementia (bvFTD), Alzheimer's disease (AD), and mild cognitive impairment (MCI). We assessed 300 participants using neuropsychological memory tests-Free and Cued Selective Reminding Test (FCSRT), Brief Visuospatial Memory Test-Revised-and MTL volumetry. Propensity score matching examined which subtests were most influenced by frontal functions. Principal component analysis and ridge regression explored the relationship between MTL volumes and memory tests across groups. Significant differences in memory tests and MTL volumes followed the pattern: controls > MCI > bvFTD > AD. AD showed greater impairment than bvFTD in FCSRT Total (<i>p</i> = .013), Retention (<i>p</i> = .016), and Free Recall (<i>p</i> = .009). Correlations between MTL volumes and memory tests were strongest in MCI (<i>r</i> = -.58), followed by AD (<i>r</i> = -.36), controls (<i>r</i> = -.35), and non-significant in bvFTD (<i>r</i> = -.21). After propensity score matching, several group differences were no longer significant, including cued tasks, delayed recall, and retention. These findings support a continuum of frontal and MTL contributions to memory deficits. AD is primarily marked by MTL-related impairments, which are less pronounced in bvFTD. MTL volumetry influence on these memory tests in MCI underscores their utility in detecting subtle MTL-dependent memory dysfunction.