Breadth and age-dependency of relations between cortical thickness and cognition

Abstract

Recent advances in neuroimaging have identified a large number of neural measures that could be involved in age-related declines in cognitive functioning. A popular method of investigating neural-cognition relations has been to determine the brain regions in which a particular neural measure is associated with the level of specific cognitive measures. Although this procedure has been informative, it ignores the strong interrelations that typically exist among the measures in each modality. An alternative approach involves investigating the number and identity of distinct dimensions within the set of neural measures and within the set of cognitive measures prior to examining relations between the two types of measures. The procedure is illustrated with data from 297 adults between 20 and 79 years of age with cortical thickness in different brain regions as the neural measures, and performance on 12 cognitive tests as the cognitive measures. The results revealed that most of the relations between cortical thickness and cognition occurred at a general level corresponding to variance shared among different brain regions and among different cognitive measures. In addition, the strength of the thickness-cognition relation was substantially reduced after controlling the variation in age, which suggests that at least some of the thickness-cognition relations in age-heterogeneous samples may be attributable to the influence of age on each type of measure.

Selective association between cortical thickness and reference abilities in normal aging

“…We replicated prior accounts of the significant association of mean thickness and global cognition, and similarly found a lack of a significant association between reference abilities and mean cortical thickness as in our companion paper (Salthouse et al, 2015). In contrast to our companion paper, however, our approach found that cortical thickness patterns preserve reference-ability specific information.…”

“…First, our companion paper (Salthouse et al, 2015) conducted a principal-axis factor analysis with a subsequent oblique rotation on 33 mean values of cortical surface ROIs to retain 5 factors. In the current paper there was no such dimensionality reduction up front; we performed a principal component analysis on the data from all vertices and retained all the PCs for the subsequent regression analysis.…”

“…In addition, any performance on tests in the cognitive test battery that was indicative of mild cognitive impairment was grounds for exclusion. More detailed description about this study can be found in (Salthouse et al, 2015; Stern et al, 2014). …”

“…As described in (Salthouse et al, 2015) twelve measures were selected from a battery of neuropsychological tests to assess cognitive functioning. Three memory measures were based on sub-scores of the Selective Reminding Task (SRT) (Buschke & Fuld, 1974): the long-term storage sub-score (SRT_LTS), continuous long-term retrieval (SRT_CLRT), and the number of words recalled on the last trial (SRT_Last).…”

“…The current paper follows from, and can be contrasted with, a recent publication from our group (Salthouse et al, 2015) which examined similar thickness-cognition relations in a subset of the participants in this study. It used a coarser spatial resolution and considered 33 bilateral regions of interest.…”