Coupled Changes in Brain White Matter Microstructure and Fluid Intelligence in Later Life

Ritchie, Stuart J.; Bastin, Mark E.; Elliot M. Tucker–Drob; Maniega, Susana Muñoz; Engelhardt, Laura E.; Cox, Simon R.; Royle, Natalie A.; Gow, Alan J.; Corley, Janie; Pattie, Alison; Taylor, Adele M.; Hernández, María del C. Valdés; Starr, John M.; Wardlaw, Joanna M.; Deary, Ian J. · 2015 · OpenAlex-citations

DOI: 10.1523/jneurosci.0862-15.2015

archive: archived pipeline: cataloged verified

Get this paper ↗ (DOI — opens at the source; we link to it, we don't host it)

Summary

This study investigates the neural substrates of cognitive aging by examining longitudinal relationships between brain white matter microstructure and cognitive decline in later life. While cross-sectional data suggest correlations between white matter integrity and cognitive ability, few studies have tested whether changes in these domains are coupled over time. The authors aimed to determine if declines in white matter microstructure, indexed by fractional anisotropy (FA), are associated with declines in fluid intelligence, processing speed, and memory during the eighth decade of life. This research addresses the theoretical perspective that cognitive aging may result from a "disconnection" of brain regions due to white matter degradation. The researchers utilized data from the Lothian Birth Cohort 1936, a large sample of individuals with a narrow age range. They analyzed longitudinal diffusion tensor MRI (DT-MRI) and cognitive data collected at two time points: a mean age of 73 years (n = 731) and 76 years (n = 488). White matter microstructure was assessed using probabilistic neighborhood tractography to measure FA in 12 major white matter tracts. Cognitive abilities were measured using standardized tests grouped into three domains: fluid intelligence (gf), processing speed, and memory. The authors employed multivariate latent difference score structural equation modeling to estimate latent factors for each domain and white matter FA, allowing for the analysis of change scores free from measurement error. This approach controlled for age and sex, minimizing confounding effects between-person and within-person age differences. The results demonstrated that longitudinal changes in white matter microstructure were significantly coupled with changes in fluid intelligence. Specifically, declines in FA were associated with declines in gf over the three-year interval. However, no significant coupled longitudinal changes were found between white matter FA and processing speed or memory. Additionally, the study found that individuals with higher baseline white matter FA experienced less subsequent decline in processing speed, indicating a protective effect of initial white matter integrity on speed-related cognitive tasks. The latent factors for cognitive abilities and FA showed high reliability and stability across the two measurement waves. These findings provide robust evidence for a longitudinal link between white matter microstructure deterioration and aging-related cognitive decline, specifically within the domain of fluid intelligence. The results support the disconnection hypothesis, suggesting that the degradation of white matter tracts contributes to the loss of fluid intelligence in older adults. By using a large, narrow-age cohort and advanced latent variable modeling, this study overcomes limitations of previous small-sample or wide-age-range studies. The distinction between coupled changes in fluid intelligence versus the protective baseline effects on processing speed highlights the nuanced nature of neural-cognitive relationships in aging, offering insights for predicting and potentially treating cognitive decline.

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed.

Summary generated by qwen3.6-27b-prismaquant on 2026-06-26; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• cognitive aging