Dopamine is an important neurotransmitter, meaning that the molecule allows brain cells to communicate with other brain cells. Unlike some neurotransmitters that can be neatly classified as involved in a particular set of behaviors or responses, dopamine's role in the body is varied. As a result, symptoms of low dopamine manifest themselves in many seemingly unrelated ways.
Physical Symptoms
The symptoms of low dopamine are variable and include both physical and psychological manifestations. Parkinson's disease, in which patients lose motor control of musculature and experience tremors and dyskinesia, is one of the easiest symptoms of low dopamine for physicians to recognize, because of the obvious presentation of the disease with regard to degeneration of movement. A 2002 article in the scientific journal Movement Disorders says that Parkinson's symptoms result from death of dopamine-related neurotransmitters in the brain.
Psychological Symptoms
Low dopamine also affects cognition and mood. Research has tied low levels of the neurotransmitter to both depression and inability to focus attention, implicating it in attention deficit hyperactivity disorder, or ADHD. A 2004 study in the scientific journal Fundamentals of Clinical Pharmacology says that low levels of dopamine plays a role in depression, but the researchers say that the relationship is complex and involves several neurotransmitters. A 2009 article in the Journal of the American Medical Association says that dopamine plays an important role in attention and that death of dopamine pathways can lead to ADHD.
Considerations
It can be difficult to diagnose low dopamine levels, since the symptoms of low dopamine are, in many cases, similar to symptoms of other psychiatric disease processes. Serotonin, for instance, activates many of the same pathways activated by dopamine. The two neurotransmitters work together to produce feelings of relaxation and normal affect, or mood, says Dr. Neil Carlson in his book, "Foundations of Physiological Psychology." Further, low dopamine levels often occur in tandem with low levels of other neurotransmitters, complicating diagnosis.
Prevention/Solution
Treating symptoms of low dopamine can be complex, particularly if symptoms are psychiatric and other neurotransmitters are involved. In the case of Parkinson's sufferers, treatment requires nothing more than elevated dopamine levels, but dopamine can't cross into the brain from the bloodstream, says Carlson. As such, a dopamine precursor molecule called L-dopa can be administered to patients. L-dopa crosses into the brain, and neurons synthesize it into dopamine, relieving Parkinson's symptoms.
Expert Insight
A 2010 article in the journal Proceedings of the National Academy of Science has another possible symptom of low dopamine--sensation-seeking behavior. The researchers suggest that those individuals who seek out sensation, whether through risk-taking or through addiction to drugs or sex, might have low levels of dopamine in the brain, and seek to increase dopamine levels through their behavior. Drug use, sex and other behaviors that produce strong sensations increase levels of dopamine in the brain.
References
- "Movement Disorders"; Pathophysiology of Parkinson's Disease: From Clinical Neurology to Basic Neuroscience and Back; H. Bergman and G. Deuschl; 2002
- "Fundamentals of Clinical Pharmacology"; Dopamine, Depression and Antidepressants; E. Dailly et al.; December 2004
- "Journal of the American Medical Association"; Evaluating Dopamine Reward Pathway in ADHD; N. Volkow et al.; September 2009
- "Foundations of Physiological Psychology"; Neil Carlson, Ph.D.; 2004
- "Proceedings of the National Academy of Science"; Inverted-U-shaped Correlation Between Dopamine Receptor Availability in Striatum and Sensation Seeking; A. Gjedde et al.; January 2010
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