Childhood obesity may signal dementia decades later, according to new research. Scientists say unhealthy weight and poor physical fitness during one’s youth increases the risk of cognitive decline in middle age.

The finding is based on more than 1,200 people tracked for over 30 years, starting when they were school-aged. The idea is that early activity levels, fitness and metabolic health may protect against dementia in our older years.

“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,” says lead author Michele Callisaya, of Monash University in Australia, in a statement.  “Importantly the study also indicates protective strategies against future cognitive decline may need to start as far back as early childhood, so the brain can develop sufficient reserve against developing conditions such as dementia in older life.”

Dementia cases worldwide will triple to over 150 million by 2050. With no cure in sight, there is an increasing focus on lifestyle factors that reduce the risk. They include getting enough exercise, eating plenty of oily fish, fruit and vegetables — while cutting down on fatty and sugary foods.

The study is the first significant study to look for links between objectively-measured fitness and obesity in childhood with cognition in middle age. It began in 1985 when the 1,244 Australian participants were aged seven to 15. They were assessed for fitness, including cardiorespiratory and muscular power and endurance tests. Waist-to-hip ratio (anthropometry) measurements were also taken.

They were followed up between 2017 and 2019 by which time they were 39 to 50. They underwent a series of computer tasks that challenged brain power. Those with the highest levels of cardiorespiratory and muscular fitness and lower average waist-to-hip ratio in childhood had better processing speed and attention.

They also had superior global cognitive function — an overall ability to carry out everyday activities and chores.

Decline can begin as early as middle-age, says Callisaya. Lower performance has been associated with mild cognitive impairment and dementia in older age. It is known that children who develop muscular strength, cardiorespiratory fitness and endurance due to sport and activity have better health outcomes later in life.

Higher adult fitness, of course, is also linked with better cognition and reduced risk of dementia later in life.

The research is published in the Journal of Science and Medicine in Sport.

South West News Service writer Mark Waghorn contributed to this report.