Paris, October 9, 2006
Cognitive difficulties and obesity : the link is becoming clearer
Some studies have already suggested a link between obesity and senile dementia, but generally at an advanced stage in each of these disorders. CNRS and Inserm researchers have just discovered a linear relationship between excess weight and certain cognitive capacities at earlier stages, in an adult population of average age and in good health. The monitoring of this population over the course of five years also demonstrated a less favorable evolution of results on standard cognitive tests among people with a high body mass index (BMI)(1). This study appeared on October 9, 2006 in the journal Neurology.
The researchers of Inserm Unit 558 at the Toulouse Medical School and the Work and Cognition Laboratory (CNRS, University of Toulouse 2) analyzed the body mass index and the performances on tests of memory, attention and speed in processing information in a population of 2223 men and women between the ages of 32 and 62. The data was gathered between 1996 and 2001 within the framework of the VISAT study (Vieillissement, santé, travail – Aging, health, work).
In all of these tests, the performances of people with high body mass indices were inferior to those of people with low BMI's. On a memory test for example, subjects with a BMI equal to 20 kg/m² remembered on average 9 words out of 16, whereas those with a BMI equal to 30 kg/m² remembered only 7 words. Furthermore, high BMI also seemed to be associated with a slight decline in memory over five years. These results were obtained after elimination of many potential biases, particularly the subject's level of education, the presence of diabetes or high blood pressure, all factors that could modify the results.
The link between BMI and cognitive functions could be explained by the action of substances secreted by the adipose cells on the neuronal tissues or by the vascular consequences of obesity, already cited in certain types of dementia.
For the moment, these results must be interpreted with caution. Future research could confirm them over a longer period of monitoring and verify whether the effects observed are specific to the cognitive capacities tested or more general. However, this work allows us to anticipate that it may be possible to prevent mental aging through early action on various eating and metabolism disorders.
1) The BMI is a corpulence index calculated in the following manner: BMI = Weight in kg/(Size in meters)2. A “normal” BMI is between 18.5 and 25 kg/m2. Beyond 30 we speak of obesity.
“Relation between body mass index and cognitive function in healthy middle-aged men and women”
M.Cournot(1,2), J.-C.Marquié(3), D.Ansiau(3), C.Martinaud(4), H.Fonds(5), J. Ferrières(1,2), et J-B.Ruidavets(1,2)
Neurology. October 6, 2006
1) Inserm Unit 558, Toulouse Medical School.
2) Department of Epidemiology, Toulouse University Hospital.
3) Work and Cognition Laboratory, CNRS UMR 5551, University of Toulouse Le Mirail
4) Inter-University Department of Preventive Medicine and Health Protection, Toulouse.
5) Labor Medical Service, Regional Work and Employment Office, Toulouse.