Executive functioning and attention in amnestic mild cognitive impairment are related to widespread grey matter integrity

Abstract

AbstractBackgroundMemory problems that are characteristic of amnestic mild cognitive impairment (aMCI) are often accompanied by difficulties in attention and executive functions (EF). Studies have consistently reported atrophy of the hippocampus and its association with memory decline in aMCI. However, it is less clear whether differences in grey matter volume (GMV) also contribute to difficulties in attention and EF. To that end, we investigated whether GMV is related to performance on a series of cognitive tests in people with aMCI.MethodGMV of 29 people with aMCI (mean age = 73.8 ± 7.6 Y, 5 F) was measured with voxel‐based morphometry and regressed against measures of task‐switching (Trail Making B‐A), inhibition (Stroop interference score), working memory (Symbol Digit Modalities), and attention (Vienna Reaction Time S1, S2, S3). Analyses were controlled for age and total intracranial volume. Because of the small sample, we used a lenient significance threshold of p < 0.001 (uncorrected) and cluster size (k) >= 20.ResultBetter task performance was related to higher GMV in widespread cortical regions. Task‐switching was mainly related to GMV in the bilateral insula (k = 924, 456, Z = 4.87, 3.79) and prefrontal areas (k = 846, Z = 4.35). Inhibition was related to volume in left posterior areas (k = 302, 300, Z = 3.93, 3.62), and working memory to volume in left temporal, parietal, and frontal cortices (k = 21‐88, Z = 3.28‐3.67). Attention to visual stimuli was associated with GMV of cerebellar (k = 20‐281, Z = 3.36‐3.59) and parieto‐occipital regions (k = 20‐76, Z = 3.28‐4.17), and attention to auditory stimuli mainly with prefrontal regions (k = 113, 49, Z = 3.96, 3.53). Interestingly, slower reactions to complex stimuli were related to higher GMV in occipital gyri (k = 28, Z = 3.56).ConclusionOur results suggest that EF and attention in people with aMCI are related to integrity of regions beyond those normally implicated in memory decline (e.g. the hippocampus). As investigation into aMCI is crucial for preventing disease progression, our findings should be further investigated by studies with a control group of healthy older adults.