Healthy people possess levels of brain chemicals that lie within a certain normal range. When internal or external factors either deplete the brain of these chemicals or stimulate it to produce excess amounts, a chemical imbalance occurs. Imbalances in the brain's chemistry can give rise to mood disorders, learning disabilities, substance abuse and muscle weakness. The most easily noticeable imbalances in the brain's chemistry are imbalances in neurotransmitters that function as stimulants or inhibitors in the neurological system.
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Depression is a symptom of an imbalance in the brain's chemistry. In depression, the brain levels of the well-being hormone serotonin, the reward hormone dopamine and the neurological inhibitor chemical GABA are lower than normal, reports a research team in the March 2010 issue of "Biological Psychiatry." As the main inhibitory neurotransmitter in the brain, GABA helps prevent the brain's neurons from entering a hyperactive state that could lead to a seizure. When the GABA levels are extremely low, however, the whole neurological state enters into a retarded or depressed state.
Anxiety and panic disorder, too, can be symptoms of an imbalance in the brain's chemistry. Anxiety is attributed to low levels of serotonin and GABA and high levels of stress hormones such as cortisol, adrenaline and noradrenaline. Insights into the mechanisms underlying depression come from the effectiveness of treatments aimed at stabilizing these chemicals, reports Ohio State neurologist David Beversdorf to Science Daily. Serotonin-reuptake inhibitors can increase the brain's level of serotonin, benzodiazepines, including Xanax and Valium, can increase the brain's level of the neurological inhibitor GABA, and betablockers, such as propranolol, can block the release of the stress hormone noradrenaline.
Alcohol is a temporary depressant of the neurological system. At the time of drinking, alcohol stimulates the secretion of the inhibitory molecule GABA. However, excessive amounts of alcohol can deplete the brain's natural resources of GABA, serotonin, dopamine and opioid peptides, says La Jolla neuroscientist George Koob to Science Daily. Alcohol furthermore triggers the release of stress chemicals that create depression, distress and tension. This asymmetry between the short-term calming effects and long-term distressing effects of alcohol may tempt alcoholics into relapse, Koob adds.
Chronic Fatique Syndrome
Chronic fatigue syndrome, or CFS, is a condition that leads to muscle achiness, muscle weakness and fatigue. To be diagnosed with CFS, the condition must have persisted for 6 months or be severe enough to interfere with daily function. A pilot study conducted by researchers at Georgetown indicates that CFS is a genuine neurological disorder. The study, published in the November 2006 issue of "BMC Neurology," showed that patients with CFS have 16 proteins in their spinal fluid in the central nervous system not found in healthy controls.
Attention Deficit Hyperactivity Disorder
People with attention deficit hyperactivity disorder may have low levels of dopamine markers, reports a research team in the September 9, 2009, issue of the "Journal of the American Medical Association." Dopamine is released in response to exciting activity and gives rise to a feeling of pleasure or reward, which can encourage a person to engage in the same kind of activity again. The researchers speculate that the low levels of dopamine in people with ADHD may explain their lack of motivation and inability to focus.