CHICAGO—Regular tea consumption is associated with better cognitive function in patients with Parkinson’s disease, according to a study by Xiang Gao, MD, PhD, and colleagues. The researchers reported their findings at the 60th Annual Meeting of the American Academy of Neurology.
Little is known about factors that predict the development of cognitive impairment in patients with Parkinson’s disease, but previous research indicates that antioxidant compounds in coffee and tea likely have neuroprotective properties, said Dr. Gao, a Research Associate in the Department of Nutrition at the Harvard School of Public Health in Boston. “In general populations, benefits of tea on cognitive function have been reported in several studies, whereas effects of coffee drinking were mixed. For example, a meta-analysis including four studies failed to find a significant association between coffee drinking and Alzheimer’s disease risk. Further, tea is particularly rich in flavonoids, which have been shown to be neuroprotective in several animal studies,” Dr. Gao told Neurology Reviews.
The authors examined 280 incident cases of Parkinson’s disease among participants in the Nurses’ Health Study and the Health Professionals Follow-Up Study to investigate whether greater consumption of coffee and tea was linked to better cognitive function. Food frequency questionnaires were used to evaluate the patients’ dietary intake prior to disease onset. Cognitive function was measured by several tests, including the Telephone Interview of Cognitive Status—a modified version of the Mini-Mental State Examination—and the immediate and delayed recall measures of the East Boston Memory Test. Other neuropsychologic assessments were the Digit Span Backwards test, a category fluency test, and delayed recall of a 10-word list to assess verbal memory. The primary outcome was global cognitive score, which was an average score based on performance on all six tests.
Patients were designated to four quartiles according to their intake of tea/coffee and caffeine/flavonoids. The highest quartile represented participants who had a higher intake compared with other study participants. “We should keep in mind that this so-called higher intake is only a relative high in this certain population,” Dr. Gao noted.
Greater intake of tea before the onset of Parkinson’s disease was associated with better cognitive function an average of seven years later. This finding was based on a higher global cognitive score after the researchers adjusted for sex, age, education, smoking, duration of Parkinson’s disease, and total energy intake. Each additional cup of tea per day was linked to a 0.2–standard deviation higher global cognitive score; this correlation was equal to delaying cognitive aging by about six years among Parkinson’s disease patients. After further adjustment for intake of caffeine and five major flavonoids, the association was still significant. However, the relationship between coffee and cognitive performance was not significant.
“These findings should be interpreted cautiously because of the observational nature of our study and the difficulty of excluding effects of unmeasured confounding variables,” Dr. Gao said. “However, because of the potential implication for the treatment of individuals with Parkinson’s disease, further studies are warranted.”