Dopamine is a chemical that signals nerves and regulates a number of important functions in the brain. Imbalances in dopamine or miscommunication in dopamine signaling can result in a number of problems, including dyskinesias, which are trouble moving. High and low dopamine causes problems, including trouble moving. It is important to consult with a physician for the diagnosis and management of health conditions.
Dopamine Systems
Dopamine exercises at least some control over behavior, thought processing, motivation, reward, hormone control, mood, sleep, attention, learning and memory. The nerves, or neurons, are mainly present in the ventral tegmental area and substantia nigra of the midbrain, and the arcuate nucleas of the hypothalamus. The dopamine in the substantia nigra of the midbrain is tied to movement disorders. High or low levels of dopamine in the substantia nigra will affect movement.
Disorders of Low Dopamine
Disorders of low dopamine cause dyskinesia by interfering with voluntary movement. Parkinson's disease involves the loss of dopamine containing neurons from the substantia nigra. It causes motor, psychiatric and other problems. Motor problems include a resting tremor, difficulty initiating and sustaining movement leading to slowness, unstable posture and rigidity. The cause is unknown, but may be from many factors. Drugs that deplete dopamine can cause similar symptoms, called parkinsonism.
Disorders of High Dopamine
Excessive levels of dopamine in the brain are often caused by drug therapy. Drugs such as levodopa for Parkinson's disease can lead to dance-like movements of the arms or head, known as chorea. Tardive dyskinesia occurs in some people who take antipsychotics chronically. Symptoms include writhing movements of the limbs and body, tremors, and involuntary movements of the face and mouth, such as repeated tongue protrusion or rolling or lip smacking.
Therapies
Disorders of dopamine depletion, such as Parkinson's disease, involve removing any offending agents and treating with drugs such as L-DOPA that can cross into the brain and raise dopamine levels. Similarly disorders of excess dopamine involve removing drugs or other contributors and temporarily adding drugs that block or decrease dopamine.
References
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci, et al.; 17th Ed 2008
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar, et al.; 8th Ed 2009
- "Neuroscience"; Dale Purves; 4th Ed. 2007
- "Physiology"; Linda S.Costanzo; 4th Ed 2008
