Why big people with big bellies may be more forgetful

A man with a big belly In Nigeria, having a big belly—or what some people refer to as potbelly—is synonymous with affluence. But those that are obese, experts say, may experience a cognitive decline or become more forgetful as they grow older. Sade Oguntola reports.

IN Africa, having a big belly, what some refer to as potbelly, is synonymous with affluence. A man with a small build is mostly looked down on and even when such a person is dressed in the native attire, he may not command as much respect as another that is very fat and with a potbelly.

This sign of affluence is, however, the sign of a man that is obese. A growing body of evidence is implicating obesity as a major risk factor for a seemingly endless list of diseases such as certain cancers, high blood pressure, high cholesterol, stroke, diabetes and gallbladder problems—even Alzheimer’s disease.

When it comes to obesity, having excess weight around the tummy, a new study in the journal Neurology says may be a reason for some people to experienc e dementia, a cognitive decline, as they grow older in age. Even an individual that develops belly fat in middle age—even among folks who are at a normal weight- is not exempted from dementia either. The finding even astounded the researchers who never thought having a big belly could have such a big effect as this

The observational study tracked some 6,500 people, ages 40 to 45, for more than three decades, starting in the mid-1970s. All participants were given a sagittal abdominal diameter (SAD) measurement, a simple procedure in which a technician uses callipers to measure the distance from the back to the upper abdomen, midway between the upper pelvis and bottom of the ribs.

At the end of the study, about 1,000 participants, or 16 per cent, were diagnosed with dementia. After factoring out known dementia risk factors such as diabetes, stroke, hypertension and high cholesterol, data analysis showed that potbellies were a bigger risk for cognitive impairment than obesity alone. In addition, the fatter the belly, the higher the risk.

Researchers used standard body mass index (BMI) measurements (weight divided by height in metres squared) to classify folks as normal weight, overweight or obese. Participants who were overweight and had a bulging belly were 2.3 times as likely to develop dementia as people with normal weight and belly size. Obese participants with large guts were 3.6 times as likely to develop dementia.

The study showed that participants with BMIs of 25 and below, those that are said to have normal weight but with a big belly, were 89 per cent more likely to develop dementia than hefty persons without a belly bulge. Having a big belly was attributed to several factors. For instance in middle-aged women, hormone loss seems to play a role in its development after 40. As women lose oestrogen, weight gathers in the midsection.

Genetics also plays a role in determining those that may be apple-shaped, with a big midsection, or pear-shaped, with a small waist but big buttocks and thighs. Some cases were linked to stress. A hormone called cortisol, released during the stress response, was implicated in developing belly fat.

Researchers do not know exactly how belly bulge plays a role in dementia, since obesity, with or without a belly, seems to affect Alzheimer’s development. But what is known is that Beta-amyloid, a naturally occurring protein that goes awry in the brains of Alzheimer’s patients, changing shape and forming plaque that disrupts normal nerve cell processes, is associated with a high BMI.

But belly fat is clearly a factor, and scientists have some ideas why. The technical term for the potbelly is visceral fat. Unlike subcutaneous fat, the stuff you can pinch, visceral fat is tucked deeper within the abdomen, surrounding vital organs such as the heart and liver. It is considered particularly dangerous since it is active, producing chemicals that can affect health.

Scientists suspect that it plays a role in inflammation, which is linked to insulin resistance, certain cancers and especially cardiovascular problems. Meanwhile, there are still a lot of unanswered questions about obesity and Alzheimer’s disease.

Nevertheless, unlike family history and age, which are important predictors for Alzheimer’s disease, all individuals can do something about their weight. Having a big belly is a risk factor that is modifiable. Visceral fat is especially amenable to diet and exercise. It is not a stubborn fat.

Research shows that women whose waists are larger than 35 inches and men whose waists are larger than 40 inches are at greater risk for disease. But even waist sizes a few inches less than that can increase your risk, though to a lesser extent.

The big question remains whether slimming down actually reduces Alzheimer’s risk. Doctors admit that a clinical trial of that sort may be difficult and unethical, since one group of patients would have to remain obese, a known health risk. That is no excuse to carry around a spare tire, says Whitmer. “About half the adults in this country have abdominal obesity,” she says. “The scale does not tell the whole story. People have to be aware of where they carry their weight and then do something about it.” To protect your brain, that something may be as simple as dropping a few pounds.

Dr. Sola Ogunniyi, the head of department of Medicine, University College Hospital (UCH), Ibadan, said being fat is regarded as a bad thing and associated with many health problems. According to him, “recent studies showed fat people are more at risk of developing dementia, a condition in which the individual is forgetful and unable to carry out normal brain functions while conscious and alert.”

The rather high incidence in obesity in developed countries of the world, he said, was suggested to be one of the reasons why dementia is higher in prevalence in these countries unlike in countries like Nigeria, where people are less fat.

He declared, “Based on data from the Ibadan Dementia group at the University College Hospital, College of Medicine, we have linked a deposition of abnormal protein in the brain, characteristic of a type of dementia to high fat level in the blood.”

“Based on these obese people tend to have higher fat (cholesterol) in the blood and so it is not surprising the association is now being reported. As people become more westernised, they become fatter and they tend towards more cases of dementia.

“This is also a warning to people to watch what they eat so that they do not put themselves at risk of such a devastating brain disease. Meanwhile there are divergent reasons proffered by experts on the link between potbelly and dementia. Dr. Rachel Whitmer, the author of the study, was of the opinion that abdominal fat would promote dementia because it may pump out substances that harm the brain. Another expert, Dr. Jose Luchsinger of the Columbia University Medical Centre in New York, who studies the connection between obesity and Alzheimer’s disease, cautioned that such a study cannot prove abdominal fat promotes dementia.Nevertheless, the study results he saidare “highly plausible”. “I am not surprised at all,” he said. High insulin levels might help explain them, he said.

Equally, Dr. Samuel Gandy, who chairs the medical and scientific advisory council of the Alzheimer’s Association, said the results fit in with previous work that indicates a person’s characteristics in middle age can affect the risk of dementia in later life.

He said it is another example of how traits associated with the risk of developing heart disease are also linked to later dementia.