Exercise and Alzheimer’s Disease

As revealed in the Journal of Biological Chemistry “Paper of the Week,” Ayae Kinoshita, a researcher at the Kyoto University Graduate School of Medicine in Japan, exercise is of great significance in fighting against Alzheimer’s disease. Alzheimer’s disease mostly occurs in individuals who are above 65 years of age and is one of the common causes of dementia. This disease is attributed to a number of factors that include the lack of regular exercise as well as an unhealthy diet that includes excess fats.

The research done by Kinoshita included a comparative analysis of voluntary exercise, diet control, and a combination of exercise and diet control in a mouse model with Alzheimer’s disease. Results indicated that regular exercise was of more benefit in reducing formation of β-amyloid—typical characteristic of Alzheimer’s disease — compared to diet control. In addition, exercise triumphed over diet control in restoration of memory loss induced by a fat-rich diet in the mice models. On the basis of this research, the Kyoto University expert recommends that the first priority should be given to exercise in the prevention of Alzheimer’s disease.

 

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According to the 2010 World Alzheimer Report as produced by the Alzheimer’s Disease International, there are approximately 35.6 million dementia cases in the world. In the 2011 Facts & Figures of the Alzheimer’s Association, there are more than 5 million Americans who have Alzheimer’s disease (AD). A new mathematical model created by scientists (for mid-life hypertension, diabetes, smoking, mid-life obesity, depression, physical inactivity and low educational attainment) allowed them to estimate the entire number of Alzheimer’s disease risk attributable to lifestyle risk factors both in the world and US combined.

The researchers reported at the Alzheimer’s Association International Conference (AAIC) 2011 that the proportion of worldwide and United States (US) Alzheimer’s cases could be attributed to seven key risk factors:

Risk Factor World US
Physical Inactivity 13% 21%
Depression 11% 15%
Smoking 14% 11%
Mid-life Hypertension 5% 8%
Mid-life Obesity 2% 7%
Low Education 19% 7%
Diabetes 2% 3%

Altogether, the seven possible modifiable risk factors contributed to 50% of cases of Alzheimer’s worldwide while in the US, the number is 54%. Researchers were similarly surprised that factors such as smoking and physical inactivity contribute to a large quantity of cases compared to cardiovascular disease. However, this also suggests that simple changes in lifestyle such as regular physical activity and stopping smoking could have a drastic impact on the cases of Alzheimer’s disease over time.

According to calculations, a 10% decrease in all the risk factors could halt 1.1 million cases of Alzheimer’s worldwide as well as 184,000 cases in America. Take note that a reduction of 25% in all the risk factors could halt more than three million cases of Alzheimer’s in the world and 492,000 cases in America.

In the study conducted by Deborah Barnes,  Associate Professor of Psychiatry at the University of California – San Francisco and  San Francisco and Mental Health Research PI at the Veterans Affair Medical Center at San Francisco, she reports that what mattered was the common risk factors in the population. She adds that the study’s focus was how the risk factors were common within the population. In the US alone, a third of the population leads a sedentary lifestyle. A large quantity of cases could be attributed to physical inactivity. Smoking similarly contributed to a large number of cases.

According to Barnes, the estimates offer a valuable assumption – that there is a direct relationship between the studied risk factors as well as Alzheimer’s disease. The next step is to do an intervention to discover if changing such risk factors will decrease the risk of Alzheimer’s. The results of the study are to be published on the Lancet Neurology online.

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A new gene called MTHFD1L has been discovered by a team of researchers led by Margaret Pericak-Vance, Ph.D., director of the John P. Hussman Institute for Human Genomics (HIHG) at the University of Miami Miller School of Medicine. It appears to increase the risk of late-onset Alzheimer’s disease (AD) which accounts for 95% of Alzheimer’s cases. This gene might explain about 5 percent of the inherited AD. The study found that individuals with a particular variation in the gene MTHFD1L may be almost twice as likely to develop AD as those people without the variation.

So far, we believe that:

  • 60 to 80% of Alzheimer’s disease is attributable to genetic and environmental factors
  • 40% of that genetic effect is attributable to the ApoE4 variant

The importance of this study is that high levels of homocysteine are a strong risk factor for late-onset Alzheimer’s disease and the MTHFD1L gene is associated with the metabolism of folate and the raised homocysteine level. Look for foods rich in folate to increase your homocysteine level. Click here for suggestions. If you go for a physical on a regular basis, be sure to have your doctor include the homocysteine test in your blood work.

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