A diet containing compounds found in green tea and carrots has successfully reversed Alzheimer's-like symptoms in mice. Though studies using mice don’t always translate to humans, the discovery opens the door to potential plant-based treatments that offer protection against dementia in humans, the researchers based at the University of Southern California say.
The study also supports the idea that a combination of therapies, rather than a single magic bullet, may be the best way to treat Alzheimer's disease. Combination treatment is already the standard of care for diseases such as cancer, HIV infection and rheumatoid arthritis.
“You don't have to wait 10 to 12 years for a designer drug to make it to market; you can make these dietary changes today,” said senior author Prof Terrence Town. “I find that very encouraging.”
The team genetically programmed 32 mice to develop Alzheimer’s-like symptoms and randomly split them into four groups each containing an equal number of healthy mice. For the next three months they fed the mice on a diet of epigallocatechin-3-gallate, or EGCG , a key ingredient in green tea, ferulic acid, or FA, which is found in carrots and tomatoes, a combination of both, or a placebo.
Both before and after the diet they put the mice through their paces in a series of neuropsychological tests similar to the thinking and memory tests used to assess dementia in humans. Included in them was a Y-shaped maze designed to test a mouse's spatial working memory - a skill that humans use to find their way out of a building. Healthy mice instinctively explore each arm of the Y maze, looking for food or a route to escape and entering the three arms in order.
Before the special diet, the mice genetically programmed to have Alzheimer’s-like symptoms struggled with this task. But after the diet they were able to perform as well as their mentally healthy counterparts.
“After three months, combination treatment completely restored working memory,” Prof Town said.
The results appear to be down to the ability of EGCG and FA to prevent large proteins within the mice’s brains from breaking down into smaller substances called amyloid beta plaques. These smaller proteins then clump together and interrupt the activity of neurons in the human sufferers of Alzheimer’s disease. EGCG and FA also appeared to reduce inflammation in the brain – another key feature of Alzheimer's in humans.
The team now plan to search for other dietary sources of substances that inhibit production of the sticky amyloid beta plaques.
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