New York, Oct 18 (IANS): If you wish to stay sharp in later years of life, better watch your weight now. Researchers have found that a higher body mass index, or BMI, can negatively impact cognitive functioning in older adults.

Higher BMI may lead to increased inflammation which can negatively impact brain function and cognition, the researchers explained.

"The higher your BMI, the more your inflammation goes up," said lead author of the study Kyle Bourassa from University of Arizona in the US.

The researchers analysed data from the English Longitudinal Study of Aging, which includes over 12 years' worth of information on the health, well-being and social and economic circumstances of the English population age 50 and older.

Using two separate samples from the study -- one of about 9,000 people and one of about 12,500 -- researchers looked at ageing adults over a six-year period.

They had information on study participants' BMI, inflammation and cognition, and the study, published in the journal Brain, Behavior and Immunity, found the same outcome in both samples.

"The higher participants' body mass at the first time point in the study, the greater the change in their CRP levels over the next four years," Bourassa said.

CRP stands for C-reactive protein, which is a marker in the blood of systemic inflammation in your body.

"Change in CRP over four years then predicted change in cognition six years after the start of the study. The body mass of these people predicted their cognitive decline through their levels of systemic inflammation," Bourassa explained.