Several studies attempting to link Alzheimer's disease (AD) with aluminum exposure have been done over the last few years, but the results have been inconclusive and contradictory. There is no definitive evidence that aluminum causes AD, but it appears likely that it may increase the risk of getting it.
However, aluminum is toxic to the body and excessive amounts may increase risk of other diseases, too. It would be wise to monitor your exposure to aluminum and minimize it where possible.
According to the National Institute of Environmental Health Sciences, aluminum is very abundant in our environment and there are many sources of exposure. They estimate that the average intake for most people is about 30-50 mg per day, of which only about 1% is absorbed into the body.
The most common sources are drinking water, foods and some medicines. Processed cheese and cornbread contain small amounts of aluminum, as do some common food additives. Drinking water accounts for about 1/4 of the total daily intake. Some over-the-counter medications, such as antacids and buffered aspirin also contain aluminum.
Leaching from aluminum cookware accounts for only a very small amount of the daily intake, except when cooking highly basic or acidic foods, such as tomato-based foods.
Aluminum drink cans are usually coated with a polymer to prevent leaching, so they are not a major concern.
There is greater concern for inhaled aluminum, such as that in spray antiperspirants. If you choose to use spray products that contain aluminum, be careful to avoid inhaling them.
I have not seen or heard any information regarding the amount of aluminum in tea. I suggest that you check the label for the specific tea you drink to see how much aluminum it contains. Then take into account the amount of aluminum you may be taking in from other sources, and try to avoid excessive total daily intake from all sources.