Global longitudinal study confirms obesity increases dementia risk

November 30, 2017, University College London
Credit: CC0 Public Domain

People who have a high body mass index (BMI) are more likely to develop dementia than those with a normal weight, according to a new UCL-led study.

The study, published in the Alzheimer's & Dementia journal, analysed data from 1.3 million adults living in the United States and Europe. The researchers also found that people near onset, who then go on to develop dementia, tend to have lower body weight than their dementia-free counterparts.

"The BMI-dementia association observed in longitudinal population studies, such as ours, is actually attributable to two processes," said lead author of the study, Professor Mika Kivimäki (UCL Institute of Epidemiology & Health). "One is an adverse effect of excess body fat on dementia risk. The other is weight loss due to pre-clinical dementia. For this reason, people who develop dementia may have a higher-than-average some 20 years before dementia onset, but close to overt dementia have a lower BMI than those who remain healthy."

"The new study confirms both the adverse effect of obesity as well as weight loss caused by metabolic changes during the pre-dementia stage."

Past research on how a person's weight influences their risk of dementia has produced conflicting results. Some findings have suggested that being obese poses a higher dementia risk, but other studies have linked lower weight to increased dementia incidence.

In this study, researchers from across Europe pooled individual-level data from 39 longitudinal population studies from the United States, the United Kingdom, France, Sweden, and Finland. A total of 1,349,857 dementia-free adults participated in these studies and their weight and height were assessed. Dementia was ascertained using linkage to electronic health records obtained from hospitalisation, prescribed medication and death registries.

A total of 6,894 participants developed dementia during up to 38 years of follow-up. Two decades before symptomatic dementia, higher BMI predicted dementia occurrence: each 5-unit increase in BMI was associated with a 16-33% higher risk of this condition (5 BMI units is 14.5kg for a person 5'7" (170cm) tall, approximately the difference in weight between the overweight and normal weight categories or between the obese and overweight categories). In contrast, the mean level of BMI during pre-clinical stage close to dementia onset was lower compared to that in participants who remained healthy.

In 2015, the number of people with dementia reached almost 45 million, two times more than in 1990. This study suggests that maintaining a healthy could prevent, or at least delay, dementia.

Explore further: Going to the gym in later life could lower dementia risk

More information: Mika Kivimäki et al, Body mass index and risk of dementia: Analysis of individual-level data from 1.3 million individuals, Alzheimer's & Dementia (2017). DOI: 10.1016/j.jalz.2017.09.016

Related Stories

Going to the gym in later life could lower dementia risk

November 30, 2017
Early results from a new study led by ANU indicate that people aged in their 60s and early 70s could lower their risk of dementia if they maintained a healthy weight by going to the gym to retain muscle mass.

Lupus linked with increased risk of dementia

November 8, 2017
A new International Journal of Geriatric Psychiatry study indicates that the risk of dementia may be elevated in individuals with systemic lupus erythematosus (SLE), an autoimmune disease affecting a range of systems including ...

Higher risk of dementia among frail older adults

November 16, 2017
The risk of developing dementia is around 3.5 times higher in frail older adults than in their non-frail peers, according to a new study from UCL.

Both high, low levels of magnesium in blood linked to risk of dementia

September 20, 2017
People with both high and low levels of magnesium in their blood may have a greater risk of developing dementia, according to a study published in the September 20, 2017, online issue of Neurology, the medical journal of ...

Packing on the pounds in middle age linked to dementia

May 2, 2011
According to a new study, being overweight or obese during middle age may increase the risk of certain dementias. The research is published in the May 3, 2011, print issue of Neurology, the medical journal of the American ...

For women, high blood pressure in your 40s may be tied to increased risk of dementia

October 4, 2017
Women who develop high blood pressure in their 40s may be more likely to develop dementia years later, according to a study published in the October 4, 2017, online issue of Neurology, the medical journal of the American ...

Recommended for you

Hypothesis underpinning dementia research 'flawed'

October 16, 2018
A hypothesis which has been the standard way of explaining how the body develops Alzheimer's Disease for almost 30 years is flawed, according to a University of Manchester biologist.

Many cases of dementia may arise from non-inherited DNA 'spelling mistakes'

October 15, 2018
Only a small proportion of cases of dementia are thought to be inherited—the cause of the vast majority is unknown. Now, in a study published today in the journal Nature Communications, a team of scientists led by researchers ...

Scientists create new map of brain region linked to Alzheimer's disease

October 8, 2018
Curing some of the most vexing diseases first requires navigating the world's most complex structure—the human brain. So, USC scientists have created the most detailed atlas yet of the brain's memory bank.

Previously unknown genetic aberrations found to be associated with Alzheimer's progression

October 8, 2018
In a large-scale analysis of RNA from postmortem human brain tissue, researchers at the Icahn School of Medicine at Mount Sinai and Columbia University have identified specific RNA splicing events associated with Alzheimer's ...

Periodontal disease bacteria may kick-start Alzheimer's

October 4, 2018
Long-term exposure to periodontal disease bacteria causes inflammation and degeneration of brain neurons in mice that is similar to the effects of Alzheimer's disease in humans, according to a new study from researchers at ...

AI could predict cognitive decline leading to Alzheimer's disease in the next five years

October 4, 2018
A team of scientists has successfully trained a new artificial intelligence (AI) algorithm to make accurate predictions regarding cognitive decline leading to Alzheimer's disease.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.