Nowadays everyone is barraged by newspapers and TV programs about the devastating effects of obesity on the human body: Type II diabetes, hypertension (high blood pressure), cardiovascular disease, and inflammation of the joints.
But did you know that obesity actually causes loss of brain matter and impairs memory function?
That should be alarming news, especially since over 300 million people worldwide are considered obese and more than one billion people are classified as overweight.
Obese People Have Less Brain Tissue
Researchers Paul Thompson and Cyrus A. Raji, along with several colleagues, compared the brains of people who were obese, overweight, and of normal weight to see if there were differences in brain structure among the three groups.
They found that obese people had eight percent less brain tissue than normal-weight people, while overweight people had four percent less tissue. Eight percent loss may not seem a large loss, but given that the brain has roughly 100 million neurons, that loss amounts to eight billion less neurons, a very significant number.
Further research shows that this significant loss is highly targeted. People defined as obese had lost brain tissue in the frontal and temporal lobes (critical for planning and memory), the anterior cingulate gyrus (attention and executive functions), hippocampus (long-term memory), and the basal ganglia (movement).
One theory that ties memory loss to a diminished brain is that the insulin-sensitive glucose transporter GLUT4 shows a significant reduction in the binding and transporting of glucose in the cells within the hippocampus. If the cells do not receive the energy they need, they cease to function properly.
Loss or shrinkage of tissue in these areas of the brain have been linked to Alzheimer’s disease and dementia.
Obesity and High Blood Pressure Accelerate Memory Loss
The University College London found that those who are obese and have high blood pressure lose their memory and thinking skills almost 22.5% faster than those who have a healthy weight.
Researchers also found that the brain scans of these obese individuals showed brains that appeared 3.8 years older than the brains of the normal-weight participants.
Higher Calorie Consumption May Double the Risk of Memory Loss
Research suggests that eating between 2,100 and 6,000 calories a day may double the risk of memory loss, or mild cognitive impairment (MCI), among people age 70 and older. The study involved 1,233 people between the ages of 70 and 89 who were free of dementia, residing in Olmsted County, Minnesota. Participants were divided into three groups depending on their daily caloric consumption: 600 to 1526 calories per day, 1,526 to 2,143 calories per day, and finally 2,143 to 6,000 calories per day.
Researchers found that the odds of having mild cognitive impairment (MCI) more than doubled for those in the highest calorie-consuming group compared to those in the lowest calorie category.
Another team of researchers from Northwestern University and the University of Pittsburgh conducted a study on 8,745 women between the ages of 65 and 79. The participants were required to fill out questionnaires that evaluated their lifestyle, overall health and background. The results indicated that being obese seems to be directly correlated to having memory problems.
Obesity-related Memory Loss is Reversible
New research shows that losing weight through dieting can change brain activity in regions that are important for memory tasks.
A Swedish research team led by Dr. Andreas Pettersson randomly assigned 20 overweight, postmenopausal women (average age 61) to one of two healthy weight loss diets for six months. A memory test of recalling faces and names were given to the women prior to the diet and again at the end of the six months. The researchers found that memory performance had significantly improved after weight loss.
Another research team led by John Gunstad of Kent State University found that, among 150 people who weighed an average of 300 pounds, those who lost an average of 50 pounds showed improvement in multiple cognitive abilities, including memory and executive functioning, which includes organizational skills.
The take-away is this: obesity can directly impact your memory and executive functioning, especially as you become older. Maintaining a healthy weight and lifestyle may help reduce the risk of succumbing to Alzheimer’s disease, dementia and mild cognitive impairment.