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One of the ways dementia can be prevented, suggests new research published in the Journal of Alzheimer’s Disease, is by keeping one’s BMI (Body Mass Index) low. BMI is a calculation whereby someone can work out if they are at a healthy weight for their height.

The new research looked into the impact of late-life BMI on dementia risk. The results of the study suggested that women with a high BMI had a decreased risk of dementia while men who were underweight had a reduced risk of the disease.

Data from the retrospective study was taken from the Disease Analyser database (IQVIA) and studied German patient data between January 2006 to December 2019. In total, 296,767 were included in the study and it was from this cohort that the results were drawn.

The study concluded that while overweight women had a reduced risk of dementia, overweight men had an increased risk. However, what most surprised researchers was that being underweight improved male outcomes for dementia.

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Commenting on this part of the research, study author Dr Louis Jacob said: “It appears that there is a strong and positive relationship between [being] underweight and dementia in older men. In this context, cognitive impairments should be regularly assessed in older male patients with BMI<18.5 kg/m2.

“Furthermore, interventions aiming at weight gain should be implemented in this population, and these interventions may include nutritional supplements, high-energy snacks and community support services.”

Dr Jacob added that “overweight may protect against dementia in older women, suggesting that moderate weight excess in late life may be acceptable from a cognitive perspective”.

Not necessarily. Like all studies the researchers said there were caveats to be taken into account, and BMI was one of them.

According to the authors, these results do not mean a high BMI is not a conclusive indicator of low dementia risk. They wrote: “BMI may not be a reliable measure of underweight, overweight and obesity, and the use of other parameters such as waist circumference may have allowed more accurate analyses.”

Furthermore, they also added there were other limitations to the study such as the fact that “BMI was unavailable for the majority of patients followed in general practices, and this may have biased the study findings” and “there was no information in the database on physical activity and diet, although these two factors are associated with both BMI and dementia”.

As a result, the authors concluded more studies were needed in order to “corroborate or invalidate these findings in other countries and settings”. This means that this study cannot be used to draw a conclusion of the impact of BMI on dementia risk.

Alongside the lack of evidence and need for further investigation, it is important to note this was an observational rather than a causational study.

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Despite these limitations, this does not make the study redundant as it highlights the impact of physiological health on the body and demonstrates that the actions people take earlier on in life can have a dramatic impact later on.

It has long been known that physical health, particularly that of the cardiovascular system, can have an impact on neurological health. The reason for this because of the function of the cardiovascular system.

The main function of the cardiovascular system is to pass oxygen around to the main organs of the body; the higher someone’s cardiovascular health, the more oxygen that can be fed to the brain.

In conjunction with potentially helping to reduce the risk of dementia, cardiovascular health can also help to reduce the risk of strokes and heart attacks.

The main risk factors for dementia are: • Ageing • Gender and sex • Cognitive reserve • Ethnicity • Health conditions and diseases • Lifestyle factors.

Although this list may appear to cover almost every facet of life, it isn’t exhaustive, rather it is a list which has lengthened in recent years thanks to research.

Other factors believed to influence the risk of dementia onset include educational achievement and air pollution. It is proposed by one study published in the Lancet that the further someone progresses in education, the higher their cognitive reserve.

While this may seem unnerving to someone at a time of GCSEs and A-Levels, this does not mean someone who doesn’t go to university is more or less likely to develop dementia than a PhD student or university lecturer.

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