A Surprisingly Common Condition Has Been Linked to Dementia

By JUNTENDO UNIVERSITY RESEARCH PROMOTION CENTER JULY 11, 2022

Participants with sarcopenic obesity had the highest rate of mild cognitive impairment and dementia, followed by sarcopenia, obesity, and lastly the control group.

Scientists have linked dementia in the elderly to an unexpected candidate: sarcopenic obesity

Over 15% of Japanese adults over 65 suffer from dementia, a severe medical condition. It’s well known that dementia drastically reduces the quality of life for older adults, as the condition causes deteriorates their memory, thinking, and social abilities. 

Obesity, on the other hand, has become an increasingly prevalent lifestyle disease. It often occurs with poor muscle mass, a condition called sarcopenic obesity which is assessed based on body mass index (BMI) and handgrip strength. Surprisingly, this condition is known to increase the risk of cognitive impairments. This caused scientists to wonder, does this relationship apply to dementia as well? 

Sarcopenic obesity is independently associated with MCI and dementia among Japanese older adults. Credit: Juntendo University

Researchers from Juntendo University in Japan, under the direction of Dr. Yoshifumi Tamura, answered this question in a recent study that was published in Clinical Nutrition. Dr. Tamura emphasizes the significance of their work by saying “If the association 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 involved 1615 older Japanese people who were 65 to 84 years old and taking part in the Bunkyo Health Study.  According to the individuals’ sarcopenia and obesity status, the researchers separated the participants into four groups: those with obesity, those with sarcopenia, those with sarcopenic obesity, and those without obesity or sarcopenia (control). They then examined the relationship between sarcopenia, obesity, and several mental functions.

Handgrip strength of less than 28 kg for males and 18 kg for women indicated sarcopenia or poor muscular strength, whereas individuals with a BMI of more than 25 kg/m2 were classified as obese. To determine if dementia and moderate cognitive impairment (MCI) existed, two evaluation techniques were used. MCI and dementia were determined by a score of less than 22 on the Montreal Cognitive Assessment and less than 23 on the Mine-Mental State Examination, respectively.

In a brand-new study, researchers from Japan have shown how co-morbidity with sarcopenia and obesity is linked with cognitive impairment in elderly Japanese people. Credit: Juntendo University

They found that 59.4% of the population had neither obesity nor sarcopenia, 21.2% had obesity, 14.6% had sarcopenia, and 4.7% of the population had sarcopenic obesity. The participants with sarcopenic obesity had the greatest rate of MCI and dementia, followed by those with sarcopenia, obesity, and finally the control group.

When the team ran multivariate analyses to check for statistically relevant associations, they found that sarcopenic obesity was independently associated with an increased prevalence of MCI and dementia compared with the absence of sarcopenia and obesity. The study also showed that sarcopenia is significantly associated with dementia in women, but not in men.

“This study clearly demonstrates that sarcopenic obesity, defined by the combination of BMI and hand grip strength is associated with MCI and dementia among Japan’s elderly people,” says Dr. Tamura.

But what are the long-term implications of this study?

Dr. Tamura’s answer to this question is encouraging. “Since we now know that there is a strong correlation between sarcopenic obesity and dementia, we may develop new treatment methods to manage the condition, thereby even reducing the prevalence of dementia.”

Credit: “Sarcopenic obesity is associated with cognitive impairment in community-dwelling older adults: The Bunkyo Health Study” by Yuki Someya, Yoshifumi Tamura, Hideyoshi Kaga, Daisuke Sugimoto, Satoshi Kadowaki, Ruriko Suzuki, Shigeki Aoki, Nobutaka Hattori, Yumiko Motoi, Kazunori Shimada, Hiroyuki Daida, Muneaki Ishijima, Kazuo Kaneko, Shuko Nojiri, Ryuzo Kawamori and Hirotaka Watada, 16 March 2022, Clinical Nutrition.