Aging and Positive Mood: Longitudinal Neurobiological and Cognitive Correlates

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Objective

Despite the losses commonly associated with aging, older adults seem to possess particularly
preserved emotional regulation. To further understand this phenomenon, the authors
examined longitudinal trajectories between age, depressive symptoms, brain structure,
and cognition.

Methods

Seven hundred and sixteen functionally intact older adults (age M = 67.9, 56.8% female),
followed longitudinally (visit range: 1–13, M = 2.5), completed cognitive testing
and the Geriatric Depression Scale (GDS). A subset (N = 327) underwent 3T brain MRI.
Mixed-effects linear regression models were conducted controlling for sex, education,
and total intracranial volume.

Results

There was a significant interaction between age and time on GDS, such that GDS improved
with increasing age over time, but attenuated around age 71 (age*time b = 0.10, p
<0.001). Fractional anisotropy (FA) and mean diffusivity interacted with age to predict
longitudinal changes in GDS (FA: b = -0.02, p = 0.01; MD: b = 0.03, p = 0.007), such
that age-related benefits on GDS were attenuated in those with declining FA. Executive
function (EF) and processing speed also interacted with age to predict longitudinal
changes in GDS (EF: b = -0.04, p = 0.03; speed: b = 0.04, p = 0.04). Again, the positive
effect of age on GDS attenuated in those with worsening EF and speed. There were no
associations with memory, semantic fluency, or gray matter (p values >0.05).

Conclusion

EF, processing speed, and white matter integrity moderated the longitudinal relationship
between age and mood. Previous studies demonstrate the link between positivity and
better cognitive control, leading to improved mood in older adults. Our results are
not only consistent, but establish a potential neurobiological correlate. Future research
further exploring biological mechanisms driving psychological processes may have important
therapeutic implications.

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