Childhood Obesity and Fitness Linked with Mid-Life Mental Function

Keeping fit and preventing obesity in childhood could have cognitive benefits decades later, according to a study of more than 1000 middle-aged Australians.

The findings showed that children who performed best at physical challenges scored better on average than others in computerized tests involving thinking and reasoning approximately 30 years later.

Abdominal obesity in childhood was also linked with cognitive function, the researchers report in the Journal of Science and Medicine in Sport.

Importantly, the differences were still seen after accounting for academic ability and socioeconomic status in the children as well as smoking and alcohol consumption when they were middle-aged adults.

“Developing strategies that improve low fitness and decrease obesity levels in childhood are important because it could contribute to improvements in cognitive performance in midlife,” said researcher Michele Callisaya, from the National Centre for Healthy Ageing in Melbourne, Australia.

“Importantly the study also indicates that protective strategies against future cognitive decline may need to start as far back as early childhood, so that the brain can develop sufficient reserve against developing conditions such as dementia in older life.”

The processes that underlie declines in memory, attention, and executive functions such as self-control and flexible thinking can begin many decades before dementia is clinically detected.

Prior studies have linked muscular and cardiorespiratory fitness in childhood with health in later life and there is evidence to suggest that adult fitness and strength may benefit cognitive function.

For example, a stronger grip strength in midlife has been linked with a reduced risk of dementia later on.

To find out whether childhood measures of fitness are also associated with later cognition, the researchers used data collected in 1985 from 1244 children aged 7 to 15 years who participated in the Australian Childhood Determinants of Adult Health study.

Cardiorespiratory fitness was estimated from the time it took to do a 1.6 km run or walk, and muscular endurance from the number of inclined pushups in 30 seconds.

Muscular and anaerobic power were assessed through a 50m sprint and standing long-jump, respectively

In addition, the ratio of waist to hip circumference were used as a proxy for abdominal obesity to distinguish fat and lean mass. The 1159 children with complete information were then divided into six groups according to their fitness and obesity.

Participants were followed up an average of 32.8 years later, when they were an average of 44.4 years of age.

The researchers found that, compared the top group of fittest children, three other groups with poorer fitness and obesity were associated with lower cognitive scores.

For example, the nine per cent of children with the fittest profile had on average psychomotor attention scores that were 1.09 standard deviations higher in psychomotor attention and 0.71 standard deviations higher in global cognition than children who had the poorest fitness and obesity profile.

The same was true for children in the second lowest group for cardiovascular fitness.

The researchers point out that higher cardiorespiratory fitness has been linked with the volume of two parts of the brain, the hippocampus and cortex, as well as blood flow to the brain and the ability of the brain to adapt and change to new information at the junctions between nerve cells.

It has also been linked with a reduction in excessively high blood lipid levels and inflammation.

The team advises that “strategies that improve and maintain muscular fitness levels in childhood, encourage physical activity, and promote an active lifestyle, should be promoted both at home and in school curricula, particularly those which prevent obesity and reinforce lasting positive health behaviors”.