Late life depression, characterized by persistent down moods, can elevate the risk of multiple illnesses, worsen the outcome of existing medical conditions, and increase mortality in senior citizens. Japanese researchers have found a link between green tea consumption and the risk of developing depression among the elderly.
Dr. Kaijun Niu, of Tohoku University Graduate School in Sendai, and colleagues studied 1058 healthy elderly men and women, all over the age of 70. About 34% of the men and 39% of the women in the study suffered from depression symptoms and 20-24% showed signs of severe depression. The participants were surveyed on their daily intake of green tea and on depression symptoms using a 30-item Geriatric Depression Scale.
44% of those studied were less likely to have depression symptoms if they drank four or more cups of green tea daily. The researchers found the link even after considering such factors as social and economic status, gender, diet, history of medical problems, and the use of antidepressants.
There was not a similar effect found with other teas, such as black tea or oolong, or coffee. Although all teas come from the Sinensis plant, green tea is processed by steaming the leaves which preserves antioxidant levels.
Other studies have linked green tea to the lessening of psychological problems. Theanine, an amino acid commonly found in green tea, generates a tranquilizing effect on the brain by stimulating the production of alpha-brain waves associated with relaxation. It also alters levels of neurotransmitters such as serotonin and dopamine that can affect mood swings.
Although the consumption of green tea appears to be a safe option, the researchers warn that further research is needed to draw a more tangible connection between tea consumption and mental health. In addition, green tea does contain caffeine, which has not been shown to have a direct link to depression, but some individuals who are more sensitive to caffeine effects may experience adverse symptoms, such as irritability or anxiety. Symptoms of depression should be evaluated by a health care professional.
The study is published in the December issue of the American Journal of Clinical Nutrition.