May 16, 2008 -- A cup of green tea may be just what the doctor ordered if you have learning and memory problems related to obstructive sleep apnea, the most common type of sleep-related breathing disorder.
Obstructive sleep apnea (OSA) starves the body of oxygen during sleep. Persons with the condition experience pauses in breathing while sleeping. This condition can cause a drop in oxygen levels, which can affect organs of the body. OSA increases your risk for high blood pressure, heart attacks, and strokes, and affects cognitive function such as learning and memory.
The powerful antioxidants found in green tea may help thwart such cognitive problems, according to a study published in this month's second issue of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine. Green tea contains compounds called polyphenols, which animal studies suggest can protect against neurodegenerative changes related to Parkinson's and Alzheimer's disease. Green tea polyphenols (GTP) work by counteracting oxidative stress in the brain. Oxidative stress is cell damage brought on by harmful molecules called free radicals. Antioxidants protect against this damage. Oxidative stress is believed to play a role in many diseases.
Signs of oxidative stress and changes in the brain have been documented among some patients with OSA, the study cites.
"OSA has been increasingly recognized as a serious and frequent health condition," study author David Gozal, MD, professor and director of Kosair Children's Hospital Research Institute at the University of Louisville, says in a news release. "A growing body of evidence suggests that the adverse neurobehavioral consequences imposed by [intermittent hypoxia] stem, at least in part, from oxidative stress."
The current study involved male rats that were intermittently deprived of oxygen during a 12-hour "night" cycle for two weeks. The intermittent oxygen deprivation was similar to that experienced by adults with OSA. The researchers gave half the rats water containing GTP and the other half plain water, and then tested the rats for markers of inflammation and oxidative stress.
After receiving the GTP cocktail or plain water drink, the rats entered a maze designed to test their spatial learning and memory abilities. In this case, the rats had to remember the location of a hidden platform.
The experiments showed that the rats treated with GTP made their way through the maze better than the other rats. The researchers say their findings suggest that the chemicals in green tea can calm learning problems related to OSA-induced hypoxia. They also found that there was chemical evidence of less oxidative stress in the rats given GTP.
GTPs "may represent a potential interventional strategy for patients" with sleep-disordered breathing," Gozal says.
Polyphenols are found in many foods and beverages, including tea, wine, and certain fruits and vegetables.