Animal study: spirulina prevents dementia
Spirulina supplementation protects your brain against dementia and Alzheimer's. At least it does if you react to spirulina in the same way as the mice used by the researchers at Buddhist Dalin Tzu-Chi General Hospital in Taiwan.

The researchers did experiments on senescence-accelerated prone-8 mice [SAMP8]. These mice age rapidly, so are favourite subjects for scientists studying anti-aging substances. The mice were given a daily 50 or 100 mg of water-extract spirulina per kilogram body weight for 12 weeks. Human equivalent: 200 or 400 mg extract daily.A control group was given nothing.
At the end of the 12 weeks, the researchers placed their mice in a cage complex that had a dark room in it. Normally mice like the dark, but when these mice entered the dark room they got an electric shock. The next day the researchers measured how many seconds the animals avoided the dark room. The longer they managed to do this, the better their brain functioned. This is the passive avoidance test.
The figures below show that spirulina supplements raised the learning capacity of the SAMP8 mice to the level of SAMR1 mice. The latter are mice that age slowly.

In the brain tissue of the untreated SAMP8 mice, the researchers found the beta-amyloid plaques that are also found in human Alzheimer's patients; the spirulina mice had almost no plaques.

The spirulina had boosted the production in the brain of endogenous detoxifying enzymes such as catalase and glutathione peroxidase. As a result fewer fatty acids in the brain cell membranes had been peroxidised, or damaged.
The spirulina extracts used in the experiment came from Far East Bio-Tec. [] The Taiwanese government, not Bio-Tec, funded the research.

J Nutr Sci Vitaminol (Tokyo). 2011;57(2):186-91.