Posts Tagged ‘Risk factor’

Nature vs. Nurture: Genetics, Environment, and Cognition

June 17, 2014

This is the title of Chapter 12 in Greenwood and Parasuman’s Nurturing the Older Brain and Mind. They begin the chapter with a quote from Rene Dubos, So Human an Animal. “Genetics and experiential factors shape the biological and behavioral manifestations of human life, but they do not suffice to account for the totatality of human nature. Man also enjoys a great degree of freedom in making decisions; he is par excellence the creature that can choose, eliminate, organize, and thereby create.”

It is unfortunate but all too often the nature vs nurture issue is regarded as a deterministic dichotomy. Behavioral geneticists have done studies, identical twins have been frequently used, to estimate topics such as how much is IQ determined by genetics and how much is determined by the environment. What these studies neglect is the interaction between genetics and the environment. Neither exists in isolation from the other. Behavior and performance are the result of the interaction between genes and the environment.

Fortunately molecular genetics provides an alternative approach to behavioral genetics. The molecular approach allows for the study of specific genes and their alleles. This research has found that a particular allele of the apolipoprotein E (APOE) gene is a major risk factor for the development of Alzheimer’s. Pay attention to the term “risk factor.” Rather than causing Alzheimer’s this particular allele increases the risk of suffering from the disease. Moreover, it is possible that age-related cognitive decline may occur only in those who possess one or two copies of this allele. It is estimated that this could include about 14% of the US population.

The weight of evidence from research on this allele suggests that this risk factor interacts with lifestyle factors. Carriers of this allele obtain a greater benefit from exercise than non-carriers for late-life cognitive functioning. This benefit is most strongly evidenced when the exercise is carried out in mid-life. Cognitive experience also confers stronger benefits on allele carriers than people who do not carrier the allele. Understand that cognitive experience benefits everyone, but it is even more beneficial for those carrying this threatening allele.

So no evidence has been found that condemns any of us to Alzheimer’s or dementia. The activities covered in Nurturing the Older Brain and Mind and the healthymemory blog should be undertaken by all of us. This advice is further underscored for those with risk factors.

© Douglas Griffith and healthymemory.wordpress.com, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.

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Reducing the Risk of Alzheimer’s Disease: Knowns and Unknowns

August 10, 2011

This title was the title of an invited address at the 2011 Meeting of the American Psychological Association (APA). The address was delivered by Dr Margaret Katz who is a professor of psychology, gerontology, and preventive medicine at the University of Southern California, where she directs the education core of the USC Alzheimer Disease Research Center. She is also the foreign adjunct professor in the Department of Medical Epidemiology and Biostatistics at the Karolinska Institute in Stockholm, Sweden.

The projections are that, unless there is signficant progress in prevention by 2040, there will be about twelve million people in the United States suffering from Alzheimer’s. Alzheimer’s accounts for about two-thirds of the cases of dementia. There is a genetic component contributing to the risk of getting Alzheimer’s, but the degree of that risk is still under research. In any case, the genetic risk factor is not something that any individual can control, so the remainder of this post will be focused on activities that reduce the risk of Alzheimer’s.

Diabetes and obesity are risk factors that increase the probability for Alzheimer’s. Depression, stress, neuroticism, and tooth loss also increase the probability of Alzheimer’s. However, there are many activities that can reduce the probability of Alzheimer’s

The higher the level of education, the lower the risk of Alzheimer’s. So returning to school and increasing one’s level of education might be an option to consider. It can also lead to a job with more occupational complexity (see below).

Cognitive engagement, that is engaging in activities that require the use of the mind. The Healthymemory Blog is devoted to increasing cognitive engagement. Mnemonic techniques are activities that engage one’s creativity, recoding abilities, imaging abilities, and also involves both hemispheres of the brain.

Occupational complexity refers to the cognitive and social demands of a job. To the extent that your occupation is complex, your risk factor is reduced.

Diet is important. The diet that is good for your heart is also good for reducing the risk of Alzheimer’s.

Light or regular physical exercise reduces risk.

Social engagement also reduces the risk for Alzheimer’s. Transactive memory involves other human beings and can lead to greater social engagement and the lowering of the risk for Alzheimer’s.
These activities also tend to lead to an increase in cognitive reserve. This refers to a reserve that retards the onset of Alzheimer’s. However, once Alzheimer’s sets in, the rate of decline is much faster. Although this might seem like bad feature, it can be interpreted that should you get Alzheimer’s and have this cognitive reserve, the amount of time suffering from the disease should be less.

The conclusion of Dr . Gatz’s presentation was that there should be a lifetime commitment to brain health. The Healthymemory Blog strongly concurs.

© Douglas Griffith and healthymemory.wordpress.com, 2011. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.