Being taller in young adulthood is associated with a lower risk of developing dementia in men, even when accounting for education, intelligence, and family genetics, research finds.
Finding ways to identify individuals at risk of dementia could help people take preventive measures or plan for their future care. The study indicates that young adult height might be one potential risk factor to consider.
Previous studies have suggested that height may be a risk factor for dementia, but much of this research was not able to take into account genetic, environmental, or other early-life factors that may be linked to both height and dementia.
“We wanted to see if body height in young men is associated with diagnosis of dementia, while exploring whether intelligence test scores, educational level, and underlying environmental and genetic factors shared by brothers explain the relationship,” says lead author Terese Sara Høj Jørgensen, assistant professor at the Section of Social Medicine in the University of Copenhagen department of public health.
To do this, Jørgensen and her colleagues analyzed data on 666,333 Danish men born between 1939 and 1959, including 70,608 brothers and 7,388 twins.
These men underwent examinations at the conscript board between 1957 and 1984 and then were in Danish national registries until 2016. From the data, the researchers identified 10,599 men who developed dementia later in life.
Over the years, the average height has changed. The adjusted analysis of the study group showed that there was about a 10% reduction in the risk of developing dementia for about every 6 cm (about 2.4 inches) of stature in individuals above the average height.
When the team took into account the potential role of intelligence or education, the unadjusted relationship between height and dementia risk was only slightly less.
The researchers also found that the relationship between height and dementia risk existed in brothers of different height. The same was true of twins, although the results for this group were less certain.
The findings suggest that genetics and family traits alone can’t explain why shorter men are at greater risk of dementia than taller ones. Most likely, environmental factors also play a role.
“A key strength of our study is that it adjusted for the potential role of education and intelligence in young men’s dementia risk, both of which may build up cognitive reserve and make this group less vulnerable to developing dementia,” says senior author Merete Osler, clinical professor at the University of Copenhagen and at the Center for Clinical Research and Prevention, Bispebjerg and Frederiksberg Hospital.
“After this adjustment, our results still point to an association between taller body height in young men and a lower risk of dementia diagnosis later in life. Our analysis of brothers further suggests that the association may have common roots in early-life environmental exposures, unrelated to family factors shared by brothers,” she adds.
An important limitation of the study is the uncertainty as to whether these findings are generalizable to women, say Osler and Jørgensen. Previous studies on potential gender differences in the relationship between height and dementia are mostly inconclusive.
The paper appears in the journal eLife. Support for the work came from the Danish Medical Research Council, the Velux Foundation, the Jascha Foundation, the Health Foundation, Doctor Sofus Carl Emil Friis and Olga Doris Friis grant, and NordForsk.
Source: University of Copenhagen