Depression, Exercise, and Genetics

Chances are some your students or their family members are currently battling depression, and thus may be interested in this story. The link between regular exercise and mood enhancement has been known for some time now. Scientists have established that exercise increases levels of neurotransmitters such as dopamine and serotonin, which in turn have the effect of mood enhancement. As long as sufficient quantities of these compounds are between brain neuron synapses, a person’s mood will be elevated. When conditions change and neurotransmitter levels fall, either due to neuron reuptake of the transmitter or lack of production, a person’s mood can deflate. One long-term effect is depression.

The AAAS’s online news service EurekAlert! posted a news release on December 2, 2007, regarding research into depression from Yale University to be published in the journal Nature Medicine. Using mice, the researchers took a close look at gene expression in the hippocampus, a part of the limbic system that is sensitive to stress hormones, depression, and anti-depressants. They found that

. . . analyses of the mice turned up 33 hippocampal exercise-regulated genes—27 of which had never been identified before…. The action of one gene in particular—VGF—was greatly enhanced by exercise. Moreover, administering VGF functioned like a powerful anti-depressant, while blocking VGF inhibited the effects of exercise and induced depressive-like behavior in the mice.

It seems the researchers have found a way to avoid or treat depression by mimicking the action of exercise. This is a different approach from the actions of current anti-depressant medications, which act on the reuptake of the neurotransmitter, striving to keep neurotransmitter levels sufficient within synapses. These medications can be expensive, can take several weeks to affect the neurons sufficiently, and work on only 65% of depression patients. Understanding the mechanisms of these newly found hippocampal exercise-regulated genes provides a pathway to approaches that may work more quickly, less expensively and more likely on a greater proportion of patients.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

Depression, genetics, and medications fall within the National Science Education Standards domains of Personal and Social Perspectives, Science and Technology, and Life Science. The story of the science itself falls within the Science as Inquiry domain. You can choose to focus on any number of these domains. For example, you could ask students to identify the relationship between drugs and science. Lead them to the idea that drug manufacturing is a manifestation of technology. Science theories predict what sorts of drugs will treat medical conditions, as well as how those medications are best delivered — via injection, inhalation, or orally for example. Technologists use science knowledge about biology and about chemistry of compounds to design a drug to address the need and solve a problem.

In terms of personal and social perspectives, how does our society view depression? What status is it associated with? Why? What organizations exist for the purpose of increasing public awareness of depression? What should individuals do if they think they are depressed or if they think someone they know is? From a life science and genetics perspective, students could research the biological causes for depression and study the relevant human anatomy and body systems. What forms of depression are commonly familial? What are the known or suspected patterns of heredity for various forms of depression?

Here are some additional resources that are part of the NSDL Middle School Portal collection to facilitate your instruction regarding depression, medicines, exercise, and genetics: President’s Council on Physical Fitness and Sports (particularly the Publications link, containing this PDF, Are People Physically Inactive Because of Their Genes?); Kids Genetics; and Science of Healthy Behaviors.

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