Longitudinal trajectories of cognitive decline and cerebral blood flow abnormalities in octogenarian men with normal global cognition

Abstract

AimsCognitive and perfusion changes have been previously observed in older men with Mini Mental State Examination scores>24 points. We aimed to investigate time change in cognitive domains in a cohort of non-demented men between age 68 and 82, and how they are expressed in regional defects estimated by Cerebral Blood Flow (rCBF). Methods103 men at age 81 with MMSE scores >24 (mean 28.4 ± 1.7), no dementia or stroke, were examined with the same cognitive test battery at age 68 and age 81: Synonyms (SRB-1), Block design (SRB-3), Paired Associates, Digit Symbol Substitution and Benton Visual Retention test. rCBF was estimated using 99mTc-HMPAO SPECT at age 82. ResultsBetween ages 68 and 82 we observed a relative decline (Δ%) of cognitive test scores: SRB-3 and Benton tests, -33.7 % (SD 16,8) and -25.8 % (SD 23.9) respectively, followed by Digit Symbol test: -22,6 % (SD 15,6). The cluster of men (46 %) could be detected, grouped on the largest test score decline and highest overall test predictors’ importance in decreasing order: Δ% SRB-3, Δ% Paired Associates, Δ% Digit Symbol, Δ% Benton VR and Δ% SRB-1. Compared to the cluster with stable cognitive functions, it expressed lower rCBF in frontal and parietal lobes, and in subcortical areas. ConclusionNearly half of the studied, community-dwelling cohort of non-demented, octogenarian men with MMSE > 24, had a combination of decreasing visuospatial ability and episodic memory during preceding years, expressed by widespread rCBF changes in fronto-subcortical areas.