April 3, 2015 -- A green tea habit is tied to a lower risk for dementia and mild declines in thinking and memory among older people, a new Japanese study shows. The piping-hot perk doesn't seem to apply to black tea or coffee, though, the researchers say.
In the study, they looked at the tea- and coffee-drinking habits of people older than 60. The people were grouped by how often they drank green tea: not at all, 1 to 6 days a week, or every day. (The 3 groups didn’t differ by gender, smoking status, alcohol use, or coffee drinking.)
Of the 723 starting participants, 490 completed a follow-up survey. The results showed that drinking green tea 1 to 6 days per week or every day was linked to less mental decline. People who didn't drink it, on the other hand, scored slightly lower on a thinking and memory test. They also had fewer hobbies and years of education, and they got less exercise, all factors previously tied to worse thinking ability.
One drawback is that the researchers didn't say how long the participants had been drinking green or black tea or coffee throughout their lives. They presented their results at the 2015 International Conference on Alzheimer's and Parkinson's Diseases.
Other studies suggest that all three drinks offer certain health perks. And one dementia researcher at the conference said he wouldn't dismiss black tea or coffee from the conversation on mental decline. Knud Larsen, PhD, of Aarhus University, said coffee might help guard against Parkinson's disease and dementia.
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.
Dr Larsen has received research funding from Lundbeck Foundation.