Longevity Briefs: How Cognitive Control Changes Throughout Life

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

Our ability to focus, make decisions, and ignore distractions – collectively known as cognitive control – is fundamental to everyday function. It will come as no surprise to anyone that adults have better cognitive control than children, but throughout life, that cognitive control begins to degrade. This leads to an ‘inverted U-shape’ relationship – cognitive control increases in early adult life, peaks, then declines.

In this study, researchers comb through the data to investigate how brain activity related to cognitive control evolves (and devolves) with advancing age. While it’s broadly accepted that cognitive control declines in older age (based on cognitive tests), how the underlying brain activity reflects this is less well studied.

The discovery:

Researchers conducted a systematic meta-analysis – instead of conducting a single large study, they combined the results of numerous existing studies focusing specifically on conflict processing – a core component of cognitive control involving making a decision in the presence of conflicting or distracting information. An example of a task involving conflict processing is the Stroop test, in which a person is shown text spelling out a colour and must name the colour of the font. For example, if shown the text ‘RED’ in blue font, they would need to say ‘blue’.

In their meta-analysis, the researchers included studies that performed whole-brain functional neuroimaging on participants from a wide rage of age groups. This lead to the inclusion of 139 studies with 3765 participants in total, with ages ranging from 5 to 85 years, and allowed researchers to observe how brain activity during conflict processing tasks changed throughout life.

They found that just as in the case of functional test performance, the trajectory for brain activity related to cognitive control followed an inverted U-shaped relationship: it increased in early life, peaked between ages 27 and 36, and slowly declined thereafter. They also observed a U-shaped relationship in laterality (the degree to which one brain hemisphere is more involved than the other). Young adults had less left-hemisphere laterality than children or older adults.

The implications:

The findings suggest that cognitive control usually peaks between 27 and 36 years of age – our brains are most efficient at managing conflict and distractions during young adulthood, with a gradual decline thereafter. However, it also challenges some of the existing theories about compensation for cognitive decline. For example, it has been suggested that older brains offset the effects of cognitive decline by recruiting additional brain regions during tasks, including a decrease in laterality. However, this study found that young adults actually had less laterality, which could indicate a more balanced and efficient use of both hemispheres, or that the resources in the right hemisphere decline at a more rapid rate during ageing.

It’s not all doom and gloom, though. Decline in cognitive function is observed across large samples, but there is still considerable variation between individuals. Research suggests that with a healthy lifestyle and continued use of cognitive faculties, cognitive decline can be greatly slowed. When it comes to daily living, some elements of cognitive decline may also be offset by life experience.