Sarah Floud, Ph.D., of the Nuffield Department of Population Health at the University of Oxford in the United Kingdom, is the lead author of the study.

As Floud and her colleagues explain in their paper, some previous studies have found an association between a low body mass index (BMI) and the likelihood of receiving a diagnosis of dementia within the next 5–10 years.

Other studies that lasted a decade or less have also linked poor diet and lack of exercise with the incidence of dementia.

However, all of the above may be the result of reverse causality, meaning that they may be consequences, rather than causes, of dementia. This situation could well be possible, explain the authors, because dementia typically affects cognition a decade before the person formally receives a diagnosis.

During this preclinical stage, the condition can slowly but gradually affect behavior, impair mental and physical activity, reduce the intake of food and calories, and cause weight loss.

Furthermore, explain the authors, some recent meta-analyses have pointed out that although in the short term, a low BMI may be associated with dementia as a result of reverse causality, over a longer period, obesity is positively associated with dementia.

Either way, prospective studies over longer periods are necessary to settle the matter of how BMI connects to dementia risk. Floud and her team set out to do exactly this.

Their findings appear in the journal Neurology.

Studying diet, inactivity, BMI, and dementia

The team examined 1,136,846 women in the U.K. They had an average age of 56 years and were free of dementia at the start of the study, between 1996 and 2001.

The women gave information about their height, weight, calorie intake, and physical activity, and the researchers clinically followed them until 2017 through the National Health Service records. These records also noted any hospital admissions for dementia. 

Stay in the know. Get our free daily newsletter

Expect in-depth, science-backed toplines of our best stories every day. Tap in and keep your curiosity satisfied.

For their study, the scientists considered a BMI of 20–24.9 as “desirable,” 25–29.9 as overweight, and 30 and over as obese. They classified women who exercised less than once a week as inactive and those who exercised at least once weekly as active.

Using Cox regression models, the team calculated the links between BMI and dementia incidence over the follow-up period, adjusting for age, height, education, smoking, alcohol intake, use of menopausal hormones, residential area, and area deprivation.

Midlife obesity linked with 21% higher risk

Over the study period, 89% of the participants had no mention of dementia in their health records. At 15 years after the start of the study, 18,695 women had received a dementia diagnosis.

Women who had obesity at the beginning of the study were 21% more likely to develop dementia than women who had a “desirable” BMI.

More specifically, 2.2% of the women with obesity went on to develop dementia in the long term, compared with 1.7% of those with a healthy BMI.

Although the findings revealed that low calorie intake and a lack of physical activity had a link with higher dementia risk in the first decade of the study, these associations gradually faded after that period, and neither calorie intake nor inactivity had a significant association with dementia risk.

Floud comments on the findings, saying, “Some previous studies have suggested poor diet or a lack of exercise may increase a person’s risk of dementia.”

“However, our study found these factors are not linked to the long-term risk of dementia. […] The short-term links between dementia, inactivity, and low calorie intake are likely to be the result of the earliest signs of the disease, before symptoms start to show,” she emphasizes.

The study is limited by the fact that it only involved women, which means that the findings may not apply to men.

The authors of a linked editorial also mention “the absence of time-dependent dynamic analyses of BMI […], crude measurement of dietary habits, and residual confounding” as study limitations.

The post Dementia: Obesity, but not diet or inactivity, raises risk appeared first on MyMedicPlus.

(MENAFN – The Conversation) If you want to reduce your risk of getting Alzheimer’s disease, there is no end ofadviceon theinternet telling youhow to do it: keep your blood pressure and blood sugar in check, lose weight, exercise more, avoid getting type 2 diabetes. Of course, doing these things is good for your general health, but ourlatest studyshows they probably do nothing to reduce your risk of getting Alzheimer’s.

Around50m peoplesuffer from dementia, and that number is expected to triple in the next three decades. The most common form of dementia isAlzheimer’s . People with this disease have a build-up of two proteins in the brain (beta-amyloid and tau), but it is not known if these proteins are a cause or a consequence of the disease. What we do know is that this proliferation of tangled proteins stops brain cells working properly, hence the typical symptoms of dementia: memory loss, confusion, difficulty performing everyday tasks, changes of behaviour, hallucinations.

In the past decade, there has been an emphasis on the role of cardiovascular disease and diabetes in the development of dementia. For a while, researchers have known that these things are associated withvascular dementia . Vascular dementia occurs because of damage to blood vessels, such asatherosclerosis , which increases the risk of dangerous bleeds or blood clots in the brain. Blood clots and bleeds stop oxygen getting to parts of the brain which then leads to the death of those brain cells.

Atherosclerosis increases the risk of bleeds and blood clots in the brain.
logika600/Shutterstock

High blood pressure and diabetesincrease the risk of atherosclerosis and so will affect the delivery of oxygen to the brain. Some argue that the consequence of these diseases increases the changes seen in the brain in Alzheimer’s disease, so it is believed that high blood pressure and diabetes increase the risk of developing Alzheimer’s.

When considering the link between these factors, it is important to bear in mind how accurate dementia diagnoses are. With the tools we have today, a person will get a dementia diagnosis, for example, Alzheimer’s or vascular dementia, with a60-90% accuracy . So between 10-30% of the people diagnosed with dementia get the wrong diagnosis.

The only accurate diagnosis

Most research about the association between high blood pressure, diabetes and Alzheimer’s disease is done in a clinic. This means that the people in these studies are alive and may have been wrongly diagnosed. The only way to diagnose a person’s dementia disorder with nearly 100% accuracy is through autopsy, analysing brain samples under a microscope, so the best way to do research on this topic is through studies based on autopsies where you can confirm that the subjects had the correct diagnoses. And this is the approach we took with ourlatest study .

We wanted to investigate if the occurrence of high blood pressure and diabetes differed between people diagnosed with Alzheimer’s compared with those diagnosed with vascular dementia. Our research was based on 268 deceased patients, older than 65. We analysed brain samples to confirm a diagnosis of Alzheimer´s or vascular dementia. Using medical records and theSwedish National Diabetes Registerwe were able to determine if our subjects had hypertension or diabetes, or both.

We found a high occurrence of both high blood pressure and type 2 diabetes among the subjects with vascular dementia. The subjects with Alzheimer’s showed a distinctly lower frequency of the two diseases.

In the group with Alzheimer’s, 37% had had high blood pressure. The corresponding proportion was 74% in the group with vascular dementia. And 12% of the group with Alzheimer’s had suffered from diabetes, compared with 31% in the group with vascular dementia. AmongSwedes , 16% above 65 years have diabetes. One may speculate that by having Alzheimer’s you have a lower risk of getting diabetes, or by having diabetes you have a lower risk of getting Alzheimer’s.

Despite these results, it is still important to keep controlling your blood pressure and avoid getting type 2 diabetes. These are factors that lead to cardiovascular disease, the leading cause of death in the world. Instead, we hope that our findings can increase the knowledge about these risk factors and dementia types. The correct associations between risk factors and disease types will help scientists avoid drawing misleading conclusions and refrain from meaningless treatment attempts.

The post Alzheimer’s disease not linked to type 2 diabetes or high blood pressure new study appeared first on MyMedicPlus.