High BMI in adolescence may harm cognitive function in middle age, study shows

While the dangerous effects of adult overweight and obesity, as reflected in a high body-mass index (a calculation of a person’s weight in kilograms divided by the square of their height in meters), on cognitive function have been well documented – the association of adolescent BMI with cognitive function in midlife have not yet been reported. However, a report being released soon by Hebrew University looks set to shed some light on the subject.

Investigating this issue, scientists at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine used weight and height data from 507 individuals tracked from over 33 years starting at age 17. The participants completed a computerized cognitive assessment at ages 48 to 52, and their socioeconomic position was assessed by multiple methods. They compared excessive BMIs and cognitive function in midlife.

“We found that higher BMI [over 25] in late adolescence and the long-term cumulative burden of BMI predicted poorer cognitive function later in life. Importantly, this study shows that an impact of obesity on cognitive function in midlife may already begin in adolescence, independently of changes in BMI over the adult life course,” said the paper’s senior author, Prof. Jeremy Kark, who worked with Israeli and American colleagues. Their study will soon appear in the Journal of Alzheimer’s Disease.

“Our results also show that taller stature was associated with better global cognitive function, independent of childhood and adult socioeconomic position, and that height increase in late adolescence, reflecting late growth, conferred a protective effect,” but this was in females only, added Irit Cohen-Manheim, a doctoral candidate at the Braun School and the lead author.

The researchers point out that while socioeconomic position may have a particularly important role in the trajectory of a person’s lifetime cognitive function, and even end in dementia, it has rarely been adequately taken into account.

“Our results are consistent with the hypothesis that childhood living conditions – as reflected also by height – influence cognitive function later in life; however, our study is unique in showing that an adverse association of higher BMI with cognitive function appears to begin in adolescence and that it appears to be restricted to adults with lower childhood socioeconomic position,” said Kark.

“Evidence for the association between impaired cognitive function in midlife and subsequent dementia supports the clinical relevance of our results. Findings of the relation of BMI in adolescence with poorer midlife cognitive status, particularly in light of the ongoing epidemic of childhood obesity, require confirmation,” said Cohen-Manheim.