Weight has crucial impact on mental health. Findings of a new research suggest that a person's weight in middle age can influence not just the odds of developing Alzheimer's disease but also the time when the condition develops.

Being obese or overweight in midlife has long been suspected to increase risks for dementia, which is marked by progressive mental deterioration.

To learn more about the relationship between a person's weight in middle age and Alzheimer's, researchers from the National Institutes of Health's National Institute on Aging looked at the data of volunteers who participated in the Baltimore Longitudinal Study of Aging (BLSA), which is one of the longest running studies that focus on human aging in North America.

The researchers involved 1,394 individuals who were considered cognitively normal at baseline, 142 of whom later developed Alzheimer's disease. For their new study published in the Molecular Psychiatry on Sept. 1, the researchers reported that weight problems at midlife may predict earlier onset of the neurodegenerative disorder.

They found that among the participants of the study who eventually developed the condition, more weight during midlife was associated with earlier onset of Alzheimer's.

Individuals who had been obese, or those with BMI of 30, during midlife, for instance, developed dementia a year earlier compared with someone in the overweight range who had a BMI of 28 during midlife.

Although further study is needed to determine the link between the onset of Alzheimer's and BMI at midlife, the findings of the study suggest the importance of having healthy weight as this could help in delaying the onset of Alzheimer's.

Alzheimer's affects about 5 million people in the U.S. alone and the number is anticipated to increase by more than double come 2050 as the population gets older and in the absence of a medical breakthrough.

The condition currently has no cure and because finding an effective treatment remains elusive, researchers look for ways that could at least delay the disease and changes in lifestyle is considered a possible option.

Madhav Thambisetty, from the National Institute on Aging who led the study said that maintaining a healthy BMI in middle age will likely have long-lasting protective effects.

"In conclusion, midlife overweight predicts earlier onset of AD and greater burden of Alzheimer's neuropathology. A healthy BMI at midlife may delay the onset of AD," the researchers wrote in their study.

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