Men with lower IQ and poor cardiovascular fitness during teens at higher risk of early dementia

Men, who at the age of 18, have poorer cardiovascular fitness and/or a lower IQ more often suffer from dementia before the age of 60, according to a new study.

In several extensive studies, researchers at the Sahlgrenska Academy of Gothenburg University have previously analyzed Swedish men's conscription results and were able to show a correlation between cardiovascular fitness as a teenager and health problems in later life.

In their latest study, based on data from 1.1 million young Swedish men, the Gothenburg researcher team shows that those with poorer cardiovascular fitness and/or lower IQ in their teenage years more often suffer from early-onset dementia.

"Previous studies have shown the correlation between cardiovascular fitness and the risk of dementia in old age. Now, for the first time, we can show that the increased risk also applies to early-onset dementia and its precursors," Sahlgrenska Academy researcher Jenny Nyberg, who headed the study, said.

Expressed in figures, the study shows that men who when conscripted had poorer cardiovascular fitness were 2.5 times more likely to develop early-onset dementia later in life. A lower IQ entailed a 4 times greater risk, and a combination of both poor cardiovascular fitness and low IQ entailed a 7 times greater risk of early-onset dementia.

The increased risk remained even when controlled for other risk factors, such as heredity, medical history, and social-economic circumstances.

"We already knew that physical and cognitive exercise reduces the risk of neurological disease. Physical exercise increases nerve cell complexity and function and even generation of new nerve cells in the adult brain, which strengthens our mental and physiological functions. In other words, good cardiovascular fitness makes the brain more resistant to damage and disease," Prof. Georg Kuhn, senior author of the study, said.

The article Cardiovascular and cognitive fitness at age 18 and risk of early-onset dementia is published online in the scientific journal Brain.