Some environmental toxins may increase your risk of becoming depressed.
By Linda Wasmer Andrews
It’s sad to think how environmental toxins foul the planet, but the link between depression and pollution might be more direct than that. Certain pollutants may alter the brain in ways that help set depression in motion, studies show.
Many people can live in the same area, but not all will end up depressed. That’s where individual differences come into play. “Some people have a genetic makeup that makes them especially vulnerable,” says Charles Raison, MD, clinical director of the Mind-Body Program at Emory University.
That might sound—well, depressing. But there’s an upside, too. The more you know about how pollutants contribute to dark moods, the better you can protect yourself.
Full-blown depression steals all the joy from life and leaves you feeling as if nothing matters. It can drain energy, zap concentration or interfere with eating and sleeping habits. You may be plagued by feelings of worthlessness or preoccupied with gloomy thoughts. When genes and the environment conspire to cause depression, they change the chemistry and physiology of the brain. These brain changes, in turn, may trigger or worsen the condition’s symptoms.
Some pollutants specifically target the nervous system. What’s more, Raison says, pollutants in general activate inflammation throughout the body. “Even mild increases in inflammatory activity, day in and day out, are associated with increased depression and fatigue,” he notes.
The toxins most often linked to depression are organophosphate (OP) pesticides, ground-level ozone and lead. OP pesticides kill insects by sabotaging their nervous systems. In humans, a single high dose can cause such poisoning symptoms as headache, dizziness, weakness, vomiting, seizures and coma. Long-term exposure to lower levels can cause problems such as personality changes, confusion, anxiety, memory loss and lost appetite. One large study has found that both types of exposure may contribute to depression in farmers who apply pesticides (Environmental Health Perspectives 12/08). Another study has shown that depression risk also extends to farmers’ wives (Journal of Occupational and Environmental Medicine 10/06).
“OP exposure can disrupt serotonin in animals,” says Lorann Stallones, PhD, MPH, of Colorado State University. Abnormalities in serotonin, a brain chemical, seem to affect mood. “I think the most likely links between OPs and depression are through pathways that influence serotonin,” says Stallones.
Ozone is useful when it’s far above us in the Earth’s upper atmosphere, but the story is quite different when it’s in the air we breathe. Ground-level ozone—created from vehicle exhaust and industrial emissions—can cause chest pain, coughing, throat irritation and congestion. Research indicates that both the risk of suicide and ER visits for depression may go up when ozone levels rise (Medical Hypotheses 3/09, International Journal of Occupational Medicine and Environmental Health 2007).
“Ozone is particularly irritating to the human respiratory system, and that irritation activates inflammatory pathways,” says Raison. As the main ingredient of urban smog, ozone may also have an emotional impact that fuels a down mood. “Brown skies and foul smells register as psychologically unpleasant, hopeless places,” Raison explains.
Young children are especially vulnerable to lead’s effects on the central nervous system. But adults can be affected, too: Exposure to high levels can cause mood changes, memory loss, poor concentration and nerve disorders. A recent study in young adults has shown that exposure to even low levels of lead may boost the risk of developing depression (Archives of General Psychiatry 12/09). “The blood lead concentration associated with a higher risk of depression is common in the population and previously considered ‘safe,’” says study author Maryse Bouchard, PhD, MSc, of the University of Montreal. “Lead exposure can disrupt activity of several brain chemicals implicated in depression, such as serotonin and dopamine.”
What can you do to mitigate the depressing effects of pollution? For starters, test your older home. If built before 1978, it may have been painted with lead-based paint; if built before 1986, lead solder may have been used on the water pipes. To learn more, contact the National Lead Information Center: www.epa.gov/lead/pubs/nlic.htm, 800-424-5323.
Watch what you bring into your home. Products for controlling insect pests may contain OPs. If you use them, follow the recommended precautions. Or use alternative methods of insect control, such as manual removal, physical barriers, natural predators and nontoxic sprays. And shop organic. When you buy organic foods, you support pesticide-free farming practices.
Exercise regularly; active people are less likely to be depressed. But before exercising outside, check the forecast. The Air Quality Index (AQI) predicts daily levels of ozone and other pollution. When the AQI is high limit outdoor activity, especially from mid-afternoon to early evening. For local forecasts, visit AIRnow online (www.airnow.gov).
Finally, consider supplements. St. John’s wort, SAM-e and fish oil all show promise in fighting depression. For example, one analysis of 35 studies found fish oil to be beneficial for people with diagnosed depression (American Journal of Clinical Nutrition 3/10).
You can’t avoid pollution entirely. But you can reduce the impact toxins have on your mood.