 Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's characterized by a slowness of movement, rigidity, tremor, and stooping posture that all gets worse and worse. There's also non-movement symptoms like cognitive impairments, sleep, smell, and mood disturbances, as the disease spreads to other areas of the brain. The cause of Parkinson's is perhaps one of the most important questions posed by the science of aging. For example, why is the consumption of dairy products associated with increased risk for Parkinson's? Maybe because they contribute to our exposure to pesticides and other neurotoxins like deeldron, which continues to be found in the autopsy brains of Parkinson's victims, even though it was banned decades ago, but it lingers in the environment, and we continue to be exposed to the pesticide through contaminated dairy and other animal products. It's unlikely to be due to milk compounds such as calcium de-fat or protein, since there's no association with Parkinson's when they're derived from other sources. It could be the milk sugar, though, lactose, accounting for the increased risk of death and bone fractures, as well as Parkinson's, and earlier onset Huntington's disease, but there's a third possibility as well. Milk lowers uric acid levels, and uric acid may be protective against Huntington's, and also slow the decline of Parkinson's, and most importantly may lower the risk of getting Parkinson's in the first place, thought to be because uric acid is an important antioxidant in the brain, something we've known for over 30 years now. This can be shown directly in human nerve cells in a petri dish. Add the pesticide rotinone, and oxidative stress shoots up. Add the pro-oxidant homocysteine, and it goes up even more, but adds some uric acid, and it completely suppresses the oxidative stress caused by the pesticide. But drinking milk has a uric acid lowering effect, citing this study, describing it as a cute effect of milk, but it turned out to be just a cute typo. In a cute effect of milk on uric acid levels in the blood, drink cow's milk and uric acid levels drop 10% within hours, drink soy milk, and they go up 10% within hours. Now for the painful arthritic disease gout, which is caused by too much uric acid, the uric acid lowering effect of dairy is a good thing, but uric acid is a double-edged sword. If our uric acid levels are too high, we can get gout, but if they're too low, it may increase our risk of neurodegenerative diseases, such as Alzheimer's, Huntington's, Parkinson's, and multiple sclerosis. Here's the five-year risk of gout in men for various uric acid levels. If our uric acid is over 10, we have a 30% chance of suffering an attack of gout within the next five years, whereas at levels under 7, our risk is less than 1%. So it might make sense to have levels as high as possible without going over 7 to protect the brain without risking our joints. But having excessive uric acid in the blood puts more than just our joints in jeopardy. Yes, having too low levels may increase our risk of MS, Parkinson's, Alzheimer's, and even cancer, but having too high levels may increase our risk of gout, kidney, and heart disease. So having a uric acid level over 7 isn't just associated with increased risk of gout, but increased risk of dying from all causes, but having a low uric acid level may also shorten our lifespan by increasing mortality. High uric acid is associated with increased risk of death from heart disease, but low uric acid is associated with increased risk of fatal stroke, for example. So keeping uric acid at optimal levels, the sweet spot between 5 and 7 may protect the brain in more ways than 1. If you measure the uric acid levels in those with Parkinson's, they come in down around here, which can explain why dairy consumption may increase risk for Parkinson's because milk pushes uric acid levels down. Dairy may also explain the differences in uric acid levels between meat-eaters, vegetarians, and vegans. If you plot men out, vegans are significantly higher than vegetarians, presumably because they don't drink milk, with those eating meat and milk somewhere in between.