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Environmental Stressors and the Development of Schizophrenia

• Enhance your chances of acquiring Alzheimer’s Disease (AD) by consuming excess amounts of saturated fat from animal products (meat and dairy), trans fats from processed, baked and fast foods, and omega-6 fats from vegetable oils, margarines, fried foods and some junk foods. On the other hand, reduce your chances of getting AD by eating more omega-3 fats from fatty fish, dark green vegetables, walnuts and flax seed oil, along with omega-9 fats from olive and canola oils, avocados, and nuts. (Mind, Mood, and Memory, Mass. General Hospital, May, 2012)

• Environmental stresses such as abuse and infection have long been known to enhance the risk of young adults developing schizophrenia. This has led to the “multiple-hit hypothesis,” which argues that if during brain development the person is exposed to more than one stressor the brain is altered to become predisposed to schizophrenia in early adulthood. Schizophrenia cannot easily be measured in mice, but there are ways to measure their behaviors that are in keeping with schizophrenic behaviors in humans.

In order to test the multiple stressor hypothesis, pregnant mice were divided into four groups. One group was stressed with a mild viral infection late in pregnancy. When offspring from this group were about five weeks of age, they were exposed to unpredictable stresses (e.g., being restrained, given electric food shocks, or deprived of water). The second and third groups were exposed to infection or stress alone, while nothing was done to the fourth group. The offspring from all four groups were given a battery of behavioral tests, and later they were killed to analyze brain structure.

Only young mice exposed to a second stressor showed behaviors and brain changes found in schizophrenic humans. All other groups behaved normally. It was also found that in “schizophrenic” mice, immune cells in the brain were overactive. This study may represent a step forward in understanding how schizophrenia develops. (Science Now, Feb. 28, 2013; news.sciencemag.org/science now/2013/02/one-two-punch-of-infection-stres)

• There are hundreds of genes that cause disorders in humans, and with genetic testing it is possible to screen for more than 3,500 of them. But it is not as simple as finding a gene associated with obesity or a certain disease, for many disorders result from a complex interaction of several genes, some known and some unknown. Also, environmental factors may alter the expression of genes, a process called epigenetics. For example, if a teenager carries a gene associated with aggression it may never be expressed thanks to good parenting. For much of a person’s life, a gene or set of genes may perform normally, but aging or environmental insult might result in turning off some of these genes such that they no longer carry out their normal function. Genetic screening is helpful in providing clues to one’s future health, but there are no guarantees. (Scientific American, Jan., 2013)

• A tiny chameleon discovered on Madagascar is less than 30 mm. long and rests comfortably on the head of a match. Called Brookesia micra, it has large, sleepy-looking eyes, which help it capture tiny insects. It is a cute little reptile but probably would not make a good pet. (PLosOne, Feb. 14, 2012; Scientific American, Feb. 14, 2012)