Psychology News – A new study explains why some people experience cognitive decline with age and others do not. The results emphasize the importance of identifying factors that influence cognitive abilities in advancing age to reveal promising targets for individualized interventions.
A recent study disputes established notions of adult cognitive functioning and the compensatory power of knowledge.
Lifespan psychology has classically categorized adult cognitive functioning into two subtypes. The first is Fluid (Gf) abilities that comprise effortful processing at the time of assessment. This encompasses perceptual speed, working memory, abstract reasoning, etc. The second is crystallized (Gc) abilities that involve the retrieval and application of previously acquired knowledge. It includes vocabulary knowledge, general information, etc.
These subtypes diverge in their average age trajectories owing to neurobiological degeneration. Fluid abilities decline throughout adulthood, whereas crystallized abilities show gains into old age. These trends have led to the assumption that individuals might compensate for fluid declines with crystallized gains. This, in turn, leads to prolonging independent functioning and cognitive status in later life.
However, a new study, conducted at Max Planck Institute for Human Development, disputes this claim.
The researchers used multivariate longitudinal data from two high-quality studies which measured various crystallized and fluid abilities across time. These include the Virginia Cognitive Aging Project (VCAP) and the Betula Project (BETULA).
The results, published in Science Advances, revealed the differentiation of individual variation in rates of change in different cognitive functions.
The rates of change are strongly correlated across fluid abilities and crystallized abilities. Individual differences in cognitive development are mostly domain-general and do not follow the fluid-crystallized divide. Individuals showing greater losses in fluid abilities sometimes show smaller gains, or even losses, in crystallized abilities. Sometimes, people show no decline in fluid abilities and large gains in crystallized abilities.
Therefore, with evidence, the study explains the heterogeneity that characterizes adult cognitive functioning. It shows why some people experience cognitive decline and how some people remain mentally fit even in advancing years.
The researchers, however, partly reinstate the findings of previous studies which reveal that individual differences in cognitive abilities at a given point in time can be captured by a g-factor of intelligence and changes of cognitive abilities. A lead author of the study, Elliot Tucker-Drob, said, “Our new results confirm that changes in crystallized abilities can indeed be subsumed under a general factor of common change.”
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Tucker-Drob, E. M., de la Fuente, J., Köhncke, Y., Brandmaier, A. M., Nyberg, L., & Lindenberger, U. (2022). A strong dependency between changes in fluid and crystallized abilities in human cognitive aging. Science advances, 8(5), eabj2422. https://doi.org/10.1126/sciadv.abj2422