In addition to genetics, there are several risk factors of dementia, but according to a new study, obesity is another one and more reason to maintain a healthy weight. People with a high body mass index (BMI) were found to be more likely to develop dementia versus people with a lower BMI in study from the University College in London.
Losing weight during the preclinical dementia phase might be able to “mask the effects,” the researchers wrote. Mika Kivimäki, the study’s lead author and professor at UCL, said the link between body weight and dementia occurs for two reasons.
Obesity: One Of The Risk Factors of Dementia?
“The BMI-dementia association observed in longitudinal population studies, such as ours, is actually attributable to two processes,” she said to Science Daily. “One is an adverse effect of excess body fat on dementia risk. For this reason, people who develop dementia may have a higher-than-average body mass index some 20 years before dementia onset, but close to overt dementia have a lower BMI than those who remain healthy. The new study confirms both the adverse effect of obesity as well as weight loss caused by metabolic changes during the pre-dementia stage.”
The researchers examined 1,349,857 participants who were dementia-free from 39 cohort studies conducted in the U.S., U.K., France, Sweden and Finland. The researchers said along with measuring height and weight, they also looked at other attributes often linked with BMI and dementia risk such as education, socioeconomic position, smoking status and prevalent cardiometabolic disease.
Follow-up was done for 38 years and revealed that 6,894 of the study participants had developed dementia. The higher BMIs of the participants was able to predict the occurrence of symptomatic dementia 20 years before the onset. The researchers used electronic health records to ascertain dementia, but noted that the records were unlikely to capture all dementia cases.
The researchers wrote that each 5-unit increase in the participants’ BMI measurements linked to a 16 to 33 percent higher risk for dementia.
The average level of BMI measurements during the preclinical dementia stage close to onset was actually lower versus those who stayed healthy.
“These findings provide new evidence for the hypothesis that the association between BMI and dementia is attributable to two distinct processes; one of which is a harmful effect of higher BMI and the other reverse causation bias contributing to an inverse association between BMI and dementia,” the researchers wrote.
Other research linking weight to dementia found differing results. Some studies suggest obesity as a higher dementia risk, while others link lower weight to an increased risk for dementia.
Further research is needed to examine underlying mechanisms for weight loss during the preclinical stage, including cognitive impairment leading to impaired self-care, reduced appetite due to decreased olfactory perception or changes in the regulation of satiety and disturbed energy homeostasis,” the researchers wrote.
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