Elsevier

Biological Psychiatry

Volume 60, Issue 5, 1 September 2006, Pages 444-453
Biological Psychiatry

Original article
Regional White Matter and Neuropsychological Functioning across the Adult Lifespan

https://doi.org/10.1016/j.biopsych.2006.01.011Get rights and content

Background

The current study utilized magnetic resonance imaging (MRI) to more fully elucidate the relationship among age, regional white matter, and neuropsychological functioning.

Methods

One hundred ninety-nine neurologically healthy adults received MRI and standardized neuropsychological assessment. MR images were spatially normalized and segmented by tissue type; relative white matter values in each of the four cerebral lobes in each hemisphere were computed. Subjects were divided into Younger (ages 21–30), Middle (ages 31–54), and Older (ages 55–79) age groups.

Results

The Older group had significantly less overall relative white matter than the Middle group, who had significantly less overall relative white matter than the Younger participants (F (2, 193) = 5.42, p = 0.005). Differences in frontal lobe white matter were of largest magnitude, followed by temporal lobe (F (6, 579) = 3.32, p = 0.003). Age and frontal and temporal lobe white matter were primarily associated with performance on neuropsychological tests of executive functioning and memory. Mediational analysis suggested that frontal lobe white matter mediated the relationship between age and performance on tasks of executive functioning and memory.

Conclusions

The results confirm age-associated decline in frontal and temporal white matter, and age-related cognitive decline in several domains. Decline in neuropsychological functioning is, in part, mediated by a relative age-related reduction in frontal white matter.

Section snippets

Subjects

Subjects in the current study were participants in a large multi-site study of brain functioning across the lifespan (Brain Resource International Database; Gordon 2003, Gordon et al 2005). Each participant was carefully screened for medical or psychiatric conditions that could potentially interfere with brain or cognitive functioning. Screening was completed via a comprehensive web-based questionnaire examining personal and family history of medical and psychiatric disorders. Participants were

Results

Older participants had less overall white matter than the two younger groups (significant main effect of Age Group, F (2, 193) = 5.4186, p = .00513; see Figure 2). Post-hoc analysis using the LSD test demonstrated that the Older participants had significantly less relative white matter than the Middle group (p = .018416) and the Younger group (p = .0006674), but the two latter groups were statistically similar to each other (p = .176779). The main effect of Age Group was modified by a

Discussion

The current study provides additional evidence for a relative age-related decline in anterior white matter and neuropsychological functioning. Quantitative image analysis of frontal, temporal, parietal, and occipital lobe white matter and a comprehensive computerized neuropsychological evaluation were conducted with a sample of 199 neurologically healthy individuals across the adult lifespan. Relative white matter, particularly in the frontal and temporal lobes, was significantly reduced as a

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