FEWER PIGMENTED NEURONS IN THE LOCUS-COERULEUS OF UNCOMPLICATED ALCOHOLICS

Altered noradrenergic function is associated with alcoholism. Reduced brain norepinephrine (NE) concentrations and beta-adrenergic receptor supersensitivity following chronic alcohol consumption suggest a reduc ed level of noradrenergic neurotransmission. To further elucidate the reason for changes in noradrenergic function, we determined the number of melanin-containing noradrenergic neurons in the locus coeruleus (L C) postmortem from 11 controls and 7 alcoholics. Controls did not have a known history of psychiatric or neurologic disorders and were drug- free by toxicological screen. The diagnosis of alcohol-depend ence was based on DSM-III-R criteria. Alcoholics differed from controls in hav ing 23% fewer LC neurons (control: 43,472 +/- 1,021; alcoholic: 33,398 +/- 2184; P < 0.0005) and 46% lower density of neurons (control: 1,22 7 +/- 89 cells per mm(3); alcoholic: 663 +/- 94 cells per mm(3); P = 0 .001). The reduction in neurons was bilateral and throughout the middl e third of the LC. The two groups did not differ with respect to LC le ngth (control: 16.1 +/- 0.6 mm; alcoholic: 15.3 +/- 0.9 mm; P = 0.47) or total LC volume (control: 37.3 +/- 2.8 mm(3); alcoholic: 46.5 +/- 4 .2 mm(3); P = 0.09). Changes in noradrenergic neurotransmission in alc oholics may be due to fewer noradrenergic neurons in the locus coerule us and may contribute to memory loss and depression, common consequenc es of alcoholism.