What Obesity Does to the Brain and the Ability to Think

If you think that body fat and weight gain is just about altering your appearance or physical ailments it is time to think again, while you still can.  Obesity can have serious effects on the brain and cognitive thinking skills. Obesity has been linked to a higher risk of Alzheimer's Disease and dementia. Beyond that, neuroimaging has suggested that more morbidly obese people (BMI higher than 40) are at a greater risk for brain atrophy (shrinkage).

According to a research article from the August 21, 2012 research journal Neurology.  Scientists in Great Britain undertook to learn how obesity affects cognitive function and decline.  Over a 10 year period researchers followed 6,401 adults aged 39-63 years with the purpose of studying how body mass index (BMI) and metabolic status affected the rate of decline in cognitive function.  Participants in the study were divided into six different groups: healthy BMI no metabolic problems, healthy BMI with metabolic problems, overweight BMI no metabolic problems, overweight BMI with metabolic problems, obese BMI no metabolic problems, and obese BMI with metabolic problems.  Metabolic problems, in this study were defined as having two or more of the following problems:

• High Triglycerides or healthy levels while taking lipid-lowering medication
• Systolic blood pressure above 130 or diastolic BP over 85 or being on medication to control blood pressure
• High Glucose levels or being on medicine to control diabetes
• High HDL cholesterol levels
Any test subject with two or more of these conditions was classified as having a metabolic problem.

Every two years during the ten year period the participants were given four different scores  assessing cognitive ability.  The first score came from a test was ten minute timed test consisting of 65 math and verbal reasoning questions that increased in difficulty throughout the test.  The second score testing required the memorization and recall of twenty words to assess short-term memory.  The third scoring test required participants to write, in one minute, as many words as possible that began with the letter S.  Finally, to achieve an overall score all three scores were standardized and the averaged to give a ‘big picture’ score of cognitive function.

In analyzing the results the group of healthy BMI no metabolic problems was used to compare to the other groups.  The results of this study showed that there is significant difference in cognitive decline between the groups of metabolic problems and no problems among the obese BMI classification.  The healthy BMI groups, both problematic and not, and the overweight BMI groups declined at approximately the same rate, about 4%. However, there were significant differences in cognitive decline  between the healthy BMI groups and the obese BMI groups.  Each BMI group should some cognitive decline over the ten year period.  The healthy BMI group declined by an average of 3.6%, the overweight group declined at a rate of 4%, and the obese BMI group of no metabolic problems at 4.2%.  The obese BMI metabolic problem group declined at an average of 4.9%.

At first glance this may not seem like that big of a deal.   The difference in cognitive function is only an average of 1.3% over ten years.  But what if this study followed people from age 20 until 70, a fifty year period and found the same rate of decline every ten years during that time.  It would mean that healthy BMI people can expect a total life time decline in cognitive skills of 18% between the age 20 and age 70.  Obese people can expect a total decline of 24.5%.  Translation: maintaining a life-long healthy BMI can actually improve the ability with which the brain will function as an older adult.