There is currently little understanding on whether retrieval of proper names differs in midlife compared to young adulthood and if so, whether the age differences in this ability are associated with differences in structural integrity of the cerebral cortex. To answer these questions, we studied retrieval of proper names in 115 cognitively healthy middle-aged persons (49.7, ±3.2), comparing their performance on a tip-of-the-tongue (TOT) task with that of 68 young persons (25.4, ±3.5) from the Cam-Can data repository (http://www.mrc-cbu.cam.ac.uk/datasets/camcan/). Grey matter (GM) density and cortical thickness were used as indices of structural integrity of the cerebral cortex. The middle-aged (MA) group experienced more TOTs during proper names retrieval than young adults (YA), (t = 3.789, p < .005) and had considerably less GM density and cortical thickness across a range of brain areas bilaterally. Small clusters in left BA 45 and right BA 44 (cortical thickness) and in right BA 40 (volumetry) revealed group differences when accounting for TOTs. However, we observed no correlations between MA's TOT scores and GM volumes or cortical thickness of the brain regions typically reported as implicated in retrieval of proper names: left anterior temporal lobe, left insula, and left superior and middle temporal gyri.
Keywords: Aging; Cortical thickness; Grey matter density; Proper names; Tip-of-the-tongue states; Voxel-based morphometry.
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