Oct. 18, 2006 — Adding to the litany of health problems linked to obesity, the results of a five-year study suggest that a high body mass index may impair cognitive abilities in middle-aged adults.
A measurement of body fat based on
height and weight, BMI is used to determine
overweight and obesity. A BMI of 25 or more
is considered overweight, while 30 or more marks the obese range.
In 1996 and again in 2001, the researchers collected
medical, psychosocial and environmental data from 2,223 healthy workers aged 32
to 62. A battery of tests measured a range of cognitive abilities in the study participants.
"Cross-sectionally, a higher BMI was associated
with lower cognitive scores after adjustment for
age, sex, educational level, blood pressure,
diabetes, and other psychosocial co-variables," reported Maxime Cournot, an epidemiologist at Toulouse University School of Medicine in France, and colleagues in the current issue of Neurology.
Lower cognitive scores in overweight and obese people were particularly apparent in a test involving the memorization of word lists. Participants were given
a list of 16 words and asked to
remember them immediately and again after a delay.
While people in the lowest BMI range (15 to 21.5)
remembered on average 9 of 16 words, those in the
highest range (27.7 to 45) remembered only seven words on average.
What's more, individuals with the highest BMIs showed greater cognitive decline five years later — their recall dropped from 44 percent to 37.5 percent on
average. On the contrary, subjects in the low-BMI
range maintained the same level of recall.
"The key point of this study is that midlife
issues like obesity have an impact on cognition," David Knopman, a professor of neurology at
Mayo Clinic College of Medicine, told Discovery News. "Presumably these negative influences on the brain
are cumulative over a lifetime and increase a
person's risk of developing dementia later in
life."
According to Knopman, it is not unexpected that
obesity is associated with cognitive decline.
