Individuals with higher mid-life Body Mass Index (BMI) in the 1960s have been found to have lower memory and thinking skills and a sharper decline in these abilities in old age, compared to those with lower BMI in mid-life.

“The adverse effects of being overweight and obese are not limited to cardiac function, but also extend to brain function,” says Anna Dahl doctoral student at the School of Health Sciences, Jönköping. Several studies, including studies from the Swedish Twin Registry, have shown that individuals who are overweight or obese in mid-life are at an increased risk of suffering from dementia.

“We have extended this knowledge and shown that being overweight or obese in mid-life also negatively affects memory and thinking skills independent of dementia. Moreover, these skills decline more rapidly in old age among those who were overweight or obese in mid-life,” writes Anna Dahl in an article published in the Journal of Gerontology.

“The steeper decline in memory and thinking skills observed among individuals who were overweight or obese in mid-life, cannot be explained in our study by an increased prevalence of cardiovascular diseases,” says Anna Dahl. “There are probably other mechanisms that explain this link.”

The association between BMI and memory and thinking skills has been investigated in a study of the Swedish Twin Registry, the Swedish Adoption Twin Study of Aging (SATSA), carried out as a joint project between the School of Health Sciences, Jönköping and the Karolinska Insti­tute.