Drinking Tea Might Help to Keep Mental Sharpness
Tea is one of the most consumed beverages in the world. Drinking tea is considered to be a healthy habit that can contribute to better cognitive function during aging and reduce the risks of neurological diseases that affect mental sharpness, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD) (1).
A cross-sectional study on green tea consumption and cognitive function was conducted in 1003 Japanese subjects aged 70 or older who completed a self-administered questionnaire that included questions about the frequency of green tea consumption. The results indicated that higher consumption of green tea was associated with a lower prevalence of cognitive impairment. After adjusting for potential confounders, odds ratios (ORs) for cognitive impairment associated with different frequencies of green tea consumption were 1.00 (reference) for three or fewer cups per week, 0.62 (38% risk reduction) for four to six cups per week or one cup per day, and 0.46 (54% risk reduction) for two or more cups per day. Corresponding ORs were 1.00 (reference), 0.60 (40% risk reduction), and 0.87 (13% risk reduction) for black or oolong tea, respectively, and 1.00 (reference), 1.16, and 1.03 for coffee. This epidemiological study showed that higher consumption of green tea was associated with a lower prevalence of cognitive impairment in humans (2).
In a 5.7-year prospective cohort study, using a questionnaire, information on daily green tea consumption and other lifestyle factors was collected from elderly Japanese individuals aged 65 years or older. Among 13,645 study participants, the 5.7-year rate of incident dementia was 8.7%. More frequent green tea consumption was associated with a lower risk of incident dementia. The relative risk of dementia was reduced 17% with a 13% to 39% range for people who drank tea five or more cups per day compared with those who drank less than one cup per day (3).
A meta-analysis of a total of 26 observational studies indicated that tea intake significantly reduced the risk of cognitive disorders by 35%. Tea consumption could reduce specific risks of cognitive impairment, mild cognitive impairment, cognitive decline, and ungrouped cognitive disorders at 48%, 36%, 26%, and 24%, respectively, compared to those not drinking or rare drinking. The study found no definite beneficial effect of tea drinking on AD, but daily tea consumption was associated with a decreased risk of cognitive decline in the elderly (4).
A cross-sectional survey of 2015 study participants aged 65 or older in Zhejiang province, Eastern China, found that the prevalence rates of dementia, AD, and vascular dementia were 13.0, 6.9, and 0.5%, respectively. Being elderly, low educational level, heavy smoking, heavy alcohol consumption, diabetes, and stroke were associated with dementia, whereas tea consumption was associated with a low prevalence of AD and severe cognitive impairment (5).
Several studies have found protective associations of tea drinking to PD. A cohort study conducted in 74,941 women in urban Shanghai, aged 40–70, from 1996 to 2000, found that tea drinkers with continuous drinking of at least three times a week for six months or longer had 20% lowered risk of having PD (6). A case-controlled study with 249 PD cases and 368 control subjects reported that the intake of coffee, black tea, and Japanese and Chinese teas was inversely associated with the risk of PD. The risk of having PD was reduced in subjects whose intakes were in the highest quartile compared with those in the lowest quartile with a risk reduction of 48%, 42%, and 41%, respectively (7). A case-controlled study of 75 patients with PD and 75 control subjects found that every additional glass of tea per day decreased the risk of PD by 20% (OR = 0.8) (8). A pooled analysis of 12 studies found a clear protective effect of tea consumption in the risk estimate (OR= 0.83 or 17% risk reduction) of PD (9).
Drinking a cup of tea a day might be a good healthy habit to help relax the brain and mind, to create a mental getaway that we all need through stressful and challenging lives. Take a break and have a cup of tea every day.
References:
1. Pervin, M., Unno, K., Ohishi, T., Tanabe, H., Miyoshi, N., & Nakamura, Y. (2018). Beneficial Effects of Green Tea Catechins on Neurodegenerative Diseases. Molecules, 23(6), 1297.
2. Kuriyama, S., Hozawa, A., Ohmori, K., Shimazu, T., Matsui, T., Ebihara, S., Awata, S., Nagatomi, R., Arai, H., Tsuji, I. (2006). Green tea consumption and cognitive function: a cross-sectional study from the Tsurugaya Project. The American Journal of Clinical Nutrition, 83(2), 355–361.
3. Tomata, Y., Sugiyama, K., Kaiho, Y., Honkura, K., Watanabe, T., Zhang, S., Sugawara, Y., Tsuji, I. (2016). Green Tea Consumption and the Risk of Incident Dementia in Elderly Japanese: The Ohsaki Cohort 2006 Study. The American Journal of Geriatric Psychiatry, 24(10), 881–889.
4. Ma, Q.P., Huang, C., Cui, Q.Y., Yang, D.J., Sun, K., Chen, X., Li, X.H. (2016). Meta-Analysis of the Association between Tea Intake and the Risk of Cognitive Disorders. PLoS ONE, 11:e0165861.
5. Yang, L., Jin, X., Yan, J., Jin, Y., Yu, W., Wu, H., Xu, S. (2016). Prevalence of dementia, cognitive status and associated risk factors among elderly of Zhejiang province, China in 2014. Age Ageing, 45, 708–712.
6. Chen, H., Ding, D., Wang, J., Zhao, Q., Meng, H., Li, H., Gao, Y.T., Shu, X.O., Tanner, C.M., Hong, Z., et al. (2015). Parkinson’s disease research in a prospective cohort in China. Parkinsonism Relat. Disord., 21:1200–1204.
7. Tanaka, K., Miyake, Y., Fukushima, W., Sasaki, S., Kiyohara, C., Tsuboi, Y., Yamada, T., Oeda, T., Miki, T., Kawamura, N., et al. (2011). Intake of Japanese and Chinese teas reduces risk of Parkinson’s disease. Parkinsonism Relat. Disord., 17:446–450.
8. Hosseini Tabatabaei, N., Babakhani, B., Hosseini Tabatabaei, A., Vahabi, Z., Soltanzadeh, A. (2013). Non-genetic factors associated with the risk of Parkinson’s disease in Iranian patients. Funct. Neurol., 28:107–113.
9. Barranco Quintana, J.L., Allam, M.F., Del Castillo, A.S., Navajas, R.F. (2009). Parkinson’s disease and tea: A quantitative review. J. Am. Coll. Nutr., 28:1–6.