Vol. 9, No. 4, 2003 Page 4
Left untreated, bipolar disorder often worsens over time, with manic and depressive symptoms occurring with increasing frequency. New research indicates that this poor prognosis stems from progressive brain damage caused by the disorder.
Raymond Deicken and colleagues compared 15 non-symptomatic males with familial bipolar disorder to 20 controls, using proton magnetic resonance spectroscopy. They found significantly lower concentrations of N-acetylaspartate (NAA) in the right hippocampus of the bipolar subjects, and those who had suffered from the disease the longest had the lowest levels of NAA. NAA is the second most abundant amino acid in brain tissue, and the researchers note, "Low NAA is an indication that the integrity of neurons and/or axons has been compromised in some way, either by damage, loss, or dysfunction." The decrease in NAA over time in bipolar subjects, they say, indicates that the disease causes progressive damage. Similar decreases in NAA are seen in Alzheimer's disease, multiple sclerosis, Parkinson's disease, and other neurodegenerative diseases.
Deicken et al. say their research also confirms that the hippocampus plays a key role in bipolar disorder. Reduced hippocampal size, they note, is also seen in patients with major depression (see related article, Crime Times, 2003, Vol. 9, No. 4, Page 3).
The researchers say their findings offer insight as to why lithium is highly effective in treating bipolar disorder. Studies on humans show that lithium increases both the amount of NAA and the amount of gray matter in the brain.
"Lower concentration of hippocampal N-acetylaspartate in familial bipolar I disorder," R. F. Deicken, M. P. Pegues, S. Anzalone, R. Feiwell, and B. Soher, American Journal of Psychiatry, Vol. 160, No. 5, May 2003, 873-82. Address: Raymond Deicken, Magnetic Resonance Unit and Psychiatry Service, 116-N, Veterans Affairs Medical Center-San Francisco, 4150 Clement Street, San Francisco, CA 94121, deicken@itsa.ucsf.edu.
"Study suggests bipolar disorder may cause progressive brain damage," news release, University of California at San Francisco, May 6, 2003.