Proper dopamine metabolism also is required to maintain a state of psychological well-being. Aging humans suffer a progressive disruption of dopamine metabolism that can cause muscle weakness, loss of coordination, and depression. Parkinson's disease is caused by the premature destruction of specialized brain cells that produce dopamine. When 80 percent of dopamine-producing brain cells have died, Parkinson's disease is usually diagnosed. It is therefore desirable to protect dopamine-producing brain cells and maintain youthful dopamine metabolism throughout life.
Dopamine is formed from the amino acid L-dopa.
This could be why the drug Sinemet, which provides significant amounts of L-dopa to the brain, only works for several years before its effects wear off and the Parkinson's patient deteriorates rapidly. The combination of methylcobalamin and Sinemet therapy could be a medical breakthrough, but this can only be proven by controlled studies. Today's Parkinson's patients cannot wait for the completion of clinical studies and may want to start sublingual intake of 5 to 20 mg a day of methylcobalamin immediately. The scientists concluded that methylcobalamin is a safe and effective treatment for psychiatric disorders in patients with Alzheimer-type dementia. This is the only clinical study the Foundation could find on using methylcobalamin to treat Alzheimer's disease.