Age is one of the biggest risk factors for dementia. The older we get, the higher the risk of dementia. But what is it about advanced age that makes us more likely to develop this debilitating disease? Cardiovascular disease, chronic inflammation and even hearing loss are all correlated with dementia and are more common in seniors. Japanese scientists have added a new and rather surprising risk factor – sarcopenic obesity – to that list.
According to the latest statistical estimates, 15% of older adults in Japan (65 years and older) suffer from dementia, and the statistics are gradually increasing each year. By comparison, according to the Population Reference Bureau, about 10% of U.S. seniors aged 70 and older suffer from this serious medical condition. For Japan, a country that has traditionally had one of the lowest dementia rates in the world, this was a wake-up call.
For understandable reasons, Japanese scientists were concerned. Why are the cognitive abilities of more and more seniors languishing before their eyes?
To investigate this alarming trend, researchers from Juntendo University in Japan involved 1615 Japanese seniors aged 65-84 from the Bunkyo Health Study, an ongoing cohort study of more than 10 years. Their theory was that the increase in dementia is linked to two other factors – sarcopenia and obesity – both of which have increased the risk of cognitive problems in previous studies.
As Dr. Yoshifumi Tamura, the study’s principal investigator, pointed out to Scitech Daily, “Once the link between sarcopenic obesity and dementia is established, appropriate preventive measures can be taken to reduce the occurrence of this condition and the risk of dementia in elderly patients.”
The study was published in the March 2022 issue of the journal Clinical Nutrition.
Like dementia, obesity has gradually become more common in Japan. In the older population, this condition often goes hand in hand with sarcopenia – an age-related loss of muscle mass and strength that usually begins after the age of 40. Together, these two factors create a condition called sarcopenic obesity, in which weakness accompanies obesity.
Sarcopenic obesity is assessed using two measures: handgrip strength to test sarcopenia and body mass index (BMI) to measure obesity.
After these measurements, participants were evaluated based on their sarcopenia and obesity status and divided into four groups: participants with obesity, sarcopenia, sarcopenic obesity, and control subjects with neither obesity nor sarcopenia. The researchers then compared the cognitive and mental functions of each group to see if there was an association between sarcopenic obesity and dementia or moderate cognitive impairment (MCI).
The four groups were divided as follows:
- 4.7% of participants had sarcopenic obesity
- 14.6% had sarcopenia
- 21.2% had obesity
- 59.4% had neither obesity nor sarcopenia.
Although they made up the smallest percentage of the study population, the sarcopenic obese group had the highest rate of dementia and MCI. Sarcopenia was the second most significant risk factor, followed by obesity. The study also pointed out that sarcopenia is a significant risk factor for dementia in women, but not in men. As expected, controls came in last place, meaning they had the lowest prevalence of MCI and dementia.
In summary, the results of the study are quite clear: sarcopenic obesity may increase one’s risk of developing dementia and moderate cognitive impairment. Dr. Tamura stated, “This study clearly demonstrates that sarcopenic obesity, defined by the combination of BMI and handgrip strength, is associated with MCI and dementia in Japanese elderly people.” We eagerly await whether studies with a more diverse population will also confirm these findings. In the meantime, the results of this study can be translated into practical advice for the average person. The study proves that maintaining a healthy weight and exercising to maintain muscle strength in your older years can do much more than make you look fit. It means you have a clear and healthy mind in a capable and fit body.