Obesity associated with a higher risk for Alzheimer's, new Yorkshire-led research reveals

Obesity may contribute toward neural tissue vulnerability, while maintaining a healthy weight in mild Alzheimer’s disease could help to preserve brain structure, according to the pioneering study, by the University of Sheffield.

The findings also highlight the impact being overweight in mid-life could have on brain health in older age.

Lead author of the study, Professor Annalena Venneri, from the University of Sheffield, said: "Despite decades of ground breaking studies and a huge global research effort we still don’t have a cure for this cruel disease.

"Prevention plays such an important role in the fight against the disease.

"It is important to stress this study does not show that obesity causes Alzheimer’s, but what it does show is that being overweight is an additional burden on brain health and it may exacerbate the disease."

Alzheimer’s, also known as Alzheimer’s disease dementia, affects about 850,000 people in the UK, while 50 million people are thought to be living with the disease globally.

The disease is an irreversible, progressive brain disorder that slowly destroys memory and thinking skills and, eventually, the ability to carry out the simplest tasks.

In most people with the disease—those with the late-onset type—symptoms first appear in their mid-60s. Early-onset Alzheimer’s occurs between a person’s 30s and mid-60s and is very rare. Alzheimer’s disease is the most common cause of dementia among older adults.

"The diseases that cause dementia such as Alzheimer’s and vascular dementia lurk in the background for many years, so waiting until your 60s to lose weight is too late," said Professor Venneri, who works at the University of Sheffield's Neuroscience Institute and NIHR Sheffield Biomedical Research Centre.

"We need to start thinking about brain health and preventing these diseases much earlier. Educating children and adolescents about the burden being overweight has on multimorbidities including neurodegenerative diseases is vital."

A team of researchers from the University of Sheffield and the University of Eastern Finland examined MRI brain scans from 47 patients clinically diagnosed with mild Alzheimer’s disease dementia, 68 patients with mild cognitive impairment, and 57 cognitively healthy individuals.

The innovative study used three complementary, computational techniques to look at the anatomy of the brain, blood flow and also the fibres of the brain.

The international team compared multiple brain images and measured differences in local concentrations of brain tissues to assess grey matter volume - which degenerates during the onset of Alzheimers - white matter integrity, cerebral blood flow and obesity.

In mild dementia patients, a positive association was found between obesity and grey matter volume around the right temporoparietal junction. This suggests obesity might contribute toward neural vulnerability in cognitively healthy individuals and those with mild cognitive impairment.

The study also found that maintaining a healthy weight in mild Alzheimer’s disease dementia could help preserve brain structure in the presence of age and disease-related weight loss.

Joint author of the study, Dr Matteo De Marco, from the University of Sheffield’s Neuroscience Institute, said: "Weight-loss is commonly one of the first symptoms in the early stages of Alzheimer’s disease as people forget to eat or begin to snack on easy-to-grab foods like biscuits or crisps, in place of more nutritional meals.

"We found that maintaining a healthy weight could help preserve brain structure in people who are already experiencing mild Alzheimer’s disease dementia.

"Unlike other diseases such as cardiovascular disease or diabetes, people don’t often think about the importance of nutrition in relation to neurological conditions, but these findings show it can help to preserve brain structure.”

People who have suffered from Alzheimer's disease include The Carry On and EastEnders actress Dame Barbara Windsor who was diagnosed with Alzheimer's disease in 2014, and passed away in December last year aged 83, after her condition worsened.

Dame Barbara, who appeared in nine Carry On films and played the pub landlord Peggy Mitchell in EastEnders, did not go public with the news until 2018.

The veteran of film and TV, and her husband Scott Mitchell have campaigned to raise awareness of dementia, which is most common in people over the age of 65.

The study was conducted in collaboration with the University of Eastern Finland and the findings have been published in The Journal of Alzheimer’s Disease Reports.

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