Subjective cognitive decline predicts lower cingulo-opercular network functional connectivity in individuals with lower neurite density in the forceps minor

Abstract

Cognitive complaints of attention/concentration problems are highly frequent in older adults with subjective cognitive decline (SCD). Functional connectivity in the cingulo-opercular network (CON-FC) supports cognitive control, tonic alertness, and visual processing speed. Thus, those complaints in SCD may reflect a decrease in CON-FC. Frontal white-matter tracts such as the forceps minor exhibit age- and SCD-related alterations and, therefore, might influence the CON-FC decrease in SCD. Here, we aimed to determine whether SCD predicts an impairment in CON-FC and whether neurite density in the forceps minor modulates that effect. To do so, we integrated cross-sectional and longitudinal analyses of multimodal data in a latent growth curve modeling approach. Sixty-nine healthy older adults (13 males; mean 68.33 ± 7.95 years old) underwent resting-state functional and diffusion-weighted magnetic resonance imaging, and the degree of SCD was assessed at baseline with the memory functioning questionnaire (greater score indicating more SCD). Forty-nine of the participants were further enrolled in two follow-ups, each about 18 months apart. Baseline SCD did not predict CON-FC after three years or its rate of change (p-values > 0.092). Notably, however, the forceps minor neurite density did modulate the relation between SCD and CON-FC (intercept; b = 0.20, 95% confidence interval, CI, [0.03, 0.37], p = 0.020), so that SCD predicted a greater CON-FC decrease in older adults with relatively lower neurite density in the forceps minor. The neurite density of the forceps minor, in turn, negatively correlated with age. These results suggest that CON-FC alterations in SCD are dependent upon the forceps minor neurite density. Accordingly, these results imply modifiable age-related factors that could help delay or mitigate both age and SCD-related effects on brain connectivity.

Fornix fractional anisotropy mediates the association between Mediterranean diet adherence and memory four years later in older adults without dementia

“…Individual longitudinal trajectories are captured by a latent intercept (mean) and a latent slope (rate of change). Using LGCM, we simultaneously tested(a) the association between baseline MeDiAd and verbal episodic memory mean and rate of change over four years (five time points) and (b) the mediation of this association via baseline FA of hippocampus-relevant white-matter tracts (Fig 2-3).The latent intercept was centered on the last time point (as inRuiz-Rizzo et al, 2022), i.e., where the slope factor corresponded to zero('Mem4', Fig 2). Note that this adjustment has implications for the interpretation of the parameters related to the latent intercept(Preacher, 2018) but does not modify the interpretation of the parameters related to the latent slope, given that we kept the same scale of the time metric.…”

“…Specifically, with this adjustment, the intercept factor would now represent the variable status at time point five(Duncan & Duncan, 2009) (i.e., the latent intercept is the 'level' of memory at the fifth time point instead of at baseline). The indicators of the latent variables (i.e., the memory scores across time points) were standardized to the mean and standard deviation of the fourth follow-up to accord with the factor loading adjustment (as inRuiz-Rizzo et al, 2022). Model fit was evaluated with comparative fit index (CFI) or Tucker-Lewis index (TLI) ≥ .95; root mean square error of approximation (RMSEA) < .08; and standardized root mean square residual (SRMR) ≤ .08.…”