In patients with Parkinson's disease, the brain's dopamine-secreting neurons inexorably die off. The most common treatment to combat the tremors, slowness, and rigidity in these patients is a dopamine precursor called levodopa. But the drug's effects can decrease over time, causing a person to cycle between "on" periods of low symptoms and "off" periods of high, often-debilitating, symptoms.
A research team in Italy reports that lowering the protein content in a patient's diet can improve levodopa therapy and reduce off periods.
Researchers know that protein affects the movement of levodopa into the brain: Too little protein results in too much medication too fast, causing involuntary, jerking muscle movements. Too much protein results in too little levodopa acting against tremors and other Parkinson's symptoms.