Asymmetry in Auditory and Spatial Attention Span in Normal Elderly Genetically At Risk for Alzheimer’s Disease

Abstract

Some studies of elderly individuals with the ApoE-e4 genotype noted subtle deficits on tests of attention such as the WAIS-R Digit Span subtest, but these findings have not been consistently reported. One possible explanation for the inconsistent results could be the presence of subgroups of e4+ individuals with asymmetric cognitive profiles (i.e., significant discrepancies between verbal and visuospatial skills). Comparing genotype groups with individual, modality-specific tests might obscure subtle differences between verbal and visuospatial attention in these asymmetric subgroups. In this study, we administered the WAIS-R Digit Span and WMS-R Visual Memory Span subtests to 21 nondemented elderly e4+ individuals and 21 elderly e4-individuals matched on age, education, and overall cognitive ability. We hypothesized that a) the e4+ group would show a higher incidence of asymmetric cognitive profiles when comparing Digit Span/ Visual Memory Span performance relative to the e4-group; and (b) an analysis of individual test performance would fail to reveal differences between the two subject groups. Although the groups' performances were comparable on the individual attention span tests, the e4+ group showed a significantly larger discrepancy between digit span and spatial span scores compared to the e4-group. These findings suggest that contrast measures of modality-specific attentional skills may be more sensitive to subtle group differences in at-risk groups, even when the groups do not differ on individual comparisons of standardized test means. The increased discrepancy between verbal and visuospatial attention may reflect the presence of "subgroups" within the ApoE-e4 group that are qualitatively similar to asymmetric subgroups commonly associated with the earliest stages of AD.

Apolipoprotein E genotype and memory in the sixth decade of life

“…Visuospatial episodic memory did not differ as a function of APOE genotype in our midlife participants, but there was evidence of a cognitive asymmetry that was partially consistent with previous findings in much older individuals (10,11). In the older adults there were no mean differences according to APOE genotype, but ε4+ individuals had greater cognitive asymmetries than ε4− individuals.…”

“…Cognitive asymmetries are essentially neuropsychological probes of asymmetries between left and right cerebral hemisphere function. Greater asymmetries based on absolute differences between tests that tap primarily left versus right hemisphere function have been observed in ε4+ compared with ε4-groups (10,11). Significantly greater than normal asymmetries are thought to reflect abnormalities in brain function, as suggested by the consistency of these comparisons of ε4+ and ε4-groups with the lateralized cognitive deficits and structural brain asymmetries that are frequently observed in early AD (12).…”

Human Ecstasy Use is Associated with Increased Cortical Excitability: An fMRI Study

“…We have previously speculated that (Karageorgiou et al, 2009), as have others (Jacobson et al, 2005;Vannini et al, 2007), increased activation in the presence of normal task performance is consistent with reduced cortical efficiency. If interpreted in terms of the amount of signal change or the spatial extent in cortical or subcortical regions activated by the visual stimulus, these and earlier findings (Cowan et al, 2006;Karageorgiou et al, 2009) would be consistent with less efficient brain functioning in association with MDMA use, in that more neural work (as indirectly indexed by increased signal and therefore potential metabolic demand) and more neural volume (as indexed by the increased spatial extent of spread) are utilized for sensory response.…”

Use of Functional Magnetic Resonance Imaging in the Early Identification of Alzheimer's Disease

“…We have further demonstrated such cognitive discrepancies on tests of auditory and spatial attention (Jacobson et al, 2005b), verbal and design fluency , global versus local item processing (Jacobson et al, 2005a), response inhibition and cognitive flexibility (Wetter et al, 2005), as well as heterogeneity in verbal memory (Wetter et al, 2006). Taken together, this line of research suggests that cognitive discrepancy measures not only appear to be a useful method for identifying individuals at risk for cognitive deficits, but they also show promise in predicting those who decline.…”