Current medical thinking seems to highlight the dangers attached to being overweight when considering the general health of the population at almost every opportunity. Yet the conclusions made by recent research in the UK seem to indicate that obesity may actually assist in protecting people in middle-age from the life-changing effects of dementia as a person's mental state begins to fail. The findings have not been whole-heartedly endorsed by representatives from the Alzheimer's Society though, who advise caution before firm conclusions are made based on the study's findings, since there is still much that remains unknown about how obesity and dementia may be linked.

The new research has been carried out by members of the London School of Hygiene and Tropical Medicine and the Oxon Epidemiology group, and is thought to be the most extensive carried out up to this point. They incorporated data in their study from almost two million people classed as being middle-aged or above, utilising information provided by general practitioners' surgeries spanning a timespan of more than 20 years.

According to the study, the researchers concluded that the risks of dementia increased for people who were underweight in their middle-age (body mass index/BMI below 20), but surprisingly found that very obese people (BMI above 40) had as much as a 30% reduced risk by comparison to those of a healthy weight.

Past studies have seemed at odds with the latest research, with conventional thinking having previously indicated that the risk of dementia increased as a person's BMI became higher. The authors of the new study believe that it may well be the case that previous research did not include a large enough sample, hence the apparent difference in the findings being due to the inclusion of "random chance", to sway the outcome to that way of thinking.

Stuart Pocock, one of the authors, did not deny that obesity is commonly a factor that can result in health concerns, but he disputed that any connection should be made between the condition and dementia based on his findings.

For those interested in a more detailed analysis, the new research's findings have been published in The Lancet Diabetes and Endocrinology journal.