Confusion reigns supreme with the latest study from The Lancet Diabetes and Endocrinology journal. The study focused on dementia risks for underweight, normal and obese middle aged people.

Chronically underweight people have a higher risk of developing dementia as they age. A 30 percent uptick in risk when compared to people at a normal weight, as measured by BMI (body mass index).

When comparing the three classes of BMI, the study quickly contradicts previous findings, which placed obesity as a risk factor for developing dementia. In this study, as participants went up in BMI, protection was afforded to people with higher BMIs.

Patients with BMI score of over 30 – the obese category – actually were less likely to develop dementia than those at a healthy weight.

Researchers from The London School of Hygiene and Tropical Medicine looked at 2 million GP patient records over a span of 20 years. The figure works out to roughly 9 percent of the UK population.

dementia bmi

All participants were over the age of 40 with an average BMI of 26.5, just inside the range classified as overweight.

At the nine year follow up, 45,507 had been diagnosed with dementia.

Dementia Risk and Weight

Results from the study pointed to a 34 percent increased risk of developing dementia if you are underweight. The risk was present for at least 15 years after the weight was recorded.

What startled researchers was as the BMI number climbed, dementia rates decreased. If you had a BMI of 40, your risk of developing dementia was 29 percent lower than that of a person in a healthy weight range. The study accounted for various risk factors to get the 29 percent.

Professor Stuart Pocock, lead author of the study, remarked on the findings:

“Our results suggest that doctors, public health scientists and policy makers need to re-think how to best identify who is at high risk of dementia. We also need to pay attention to the causes and public health consequences of the link between underweight and increased dementia risk which our research has established.”

“However, our results also open up an intriguing new avenue in the search for protective factors for dementia. If we can understand why people with a high BMI have a reduced risk of dementia, it’s possible that further down the line, researchers might be able to use these insights to develop new treatments for dementia.”

BMI Criticism

While not discounting the research, other experts are pointing out the crudeness of BMI. You can have perfectly healthy people that fall into overweight categories. It’s a generic way to measure if a person is obese or not.

Most consider it a poor indicator of overall health. Fantastic. Take down the posters at the doctor’s office then.

What this study could offer up is a path to researching what is affording obese patients with protection against dementia. Could it be fat? Further research will need to be done to confirm the findings.

Until then, the standard of eating well and regular exercise holds. Healthy lifestyle choices are the key to long-term health. With conflicting studies, it’s best to stick with common sense.

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