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19-05-2011 | Mental health | Article

Overweight linked to reduced cognitive function in BD patients


Free abstract

MedWire News: Results from a preliminary Canadian study suggest that overweight/obesity may be associated with reduced cognitive function in euthymic patients with bipolar disorder (BD).

However, the researchers stress that further studies are needed to confirm their findings.

Writing in the journal European Psychiatry, Roger McIntyre (University of Toronto, Ontario) and team explain that previous studies have shown that cognitive deficits are common in BD patients, even during periods of euthymia.

"Emerging evidence also indicates that obesity is associated with reduced cognitive function in otherwise healthy individuals," they add.

To investigate whether overweight/obesity influences cognitive function in euthymic BD patients, the team studied 67 patients with the mood disorder who were aged between 18 and 60 years.

Of these, 19 (28.4%) were defined as being of normal weight, with a body mass index (BMI) of 18.5-24.9 kg/m2, and 48 were defined as overweight/obese, with a BMI 25.0 kg/m2 or greater. The average age of the two groups was 36.7 and 41.5 years, respectively.

All of the participants underwent a battery of cognitive tests to measure premorbid IQ, verbal learning and memory, attention and psychomotor processing speed, executive function, general intellectual abilities, recollection and habit memory, and self-perceptions of cognitive failures.

The researchers found that BMI was significantly and negatively correlated with attention and psychomotor processing speed as measured by the Digit Symbol Substitution Test, with mean scores of 58.68 in normal-weight BD patients versus 53.38 in overweight/obese patients.

Overweight/obese BD patients also had significantly lower scores on the Verbal Fluency Test than normal-weight patients, at 59.29 versus 70.06.

Non-significant trends suggesting a negative association with BMI were observed for most other measures of cognitive function among the participants, except for executive function and recollection memory.

McIntyre and team conclude: "Notwithstanding the post-hoc methodology and relatively small sample size, the results of this study suggest a possible negative effect of overweight/obesity on cognitive function in euthymic individuals with BD."

They add: "Taken together, these data provide the impetus for more rigorous evaluation of the mediational role of overweight/obesity (and other medical co-morbidity) on cognitive function in psychiatric populations."

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Mark Cowen

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