While many of us are familiar with the common symptoms of Alzheimer’s disease, such as gradual memory loss and changes in behaviour and mood, research suggests that a physical sign of the disease could manifest on the body decades before memory issues begin. Scientists have found a link between visceral fat – deep belly fat surrounding vital organs like the stomach, liver, and intestines – and abnormal brain proteins associated with Alzheimer’s, potentially appearing up to 20 years prior to other symptoms.
Despite being often referred to as “invisible” or “hidden fat”, there are ways to determine if you have an excess of visceral fat, including measuring your waist, your waist-to-hip ratio, and your body shape. The study, conducted by researchers at Washington University School of Medicine, involved 80 cognitively healthy adults with an average age of 49.
As reported by the Mirror, more than half of the participants (58 per cent) were classified as obese, with an average body mass index (BMI) of 32.31. For context, a BMI between 18.5 and 24.9 is deemed healthy.
Using imaging techniques, the team mapped the participants’ body composition and brain chemistry in detail. Brain positron emission tomography (PET) scans enabled them to monitor the accumulation of amyloid and tau proteins, which are key indicators of Alzheimer’s disease.
MRI scans were also utilised to gauge different types of body fat, and researchers unearthed a notable correlation between elevated levels of visceral fat and an increase in amyloid and tau build-up. Lead study author, Dr Mahsa Dolatshahi, unveiled these findings saying: “Higher visceral fat was associated with higher PET levels of the two hallmark pathologic proteins of Alzheimer’s disease—amyloid and tau.”
The research determined that visceral fat was responsible for 77 percent of the impact of high BMI on protein accumulation, whereas other types of fat demonstrated no such link. Moreover, the study showed that heightened insulin resistance and diminished levels of HDL, commonly known as “good” cholesterol, were connected to escalated brain protein accumulation.
Weighing in on the importance of these discoveries, senior study author Dr Cyrus A Raji remarked: “A key implication of our work is that managing Alzheimer’s risk in obesity will need to involve targeting the related metabolic and lipid issues that often arise with higher body fat. Knowing that visceral obesity negatively affects the brain opens up the possibility that treatment with lifestyle modifications or appropriate weight-loss drugs could improve cerebral blood flow and potentially lower the burden of and reduce the risk for Alzheimer’s disease.”
In the UK, approximately one in four adults are classified as overweight or obese. Those concerned about their weight should consult their GP for advice.