According to professor Achmad Subagio of the Research Institute of the University of Jember, drinking black coffee twice a day prevents the risk of Parkinson's disease because caffeine elevates the dopamine levels in the body. Parkinson's disease affects the brain's nerve cells that produce dopamine, a neurotransmitter responsible for transmitting signals between the nerve cells of the brain.
Drinking more coffee is linked to a lower risk of depression, according to a review of 26 studies published in Australian & New Zealand Journal of Psychiatry in 2016. For each cup of coffee consumed per day, the risk of depression decreased by 8 percent, the researchers found. However, it's worth noting that too much caffeine can cause problems in people who also suffer from anxiety, negating any beneficial effects the coffee can have on depression risk.