Differential age-related loss of pigmented locus coeruleus neurons in suicides, alcoholics, and alcoholic suicides

Abstract

We previously reported fewer locus coeruleus (LC) neurons in both suicide victims and alcoholics than among a group of nonpsychiatric controls. In the present paper we examine the rate of decline in the number of LC neurons with age, looking for possible differential rates among suicide victims, alcoholics, and controls. We also compare these groups with a group of alcoholics who died by suicide, and consider the effects of sex, race, and postmortem interval. LC neuron counts were obtained from a total of 32 subjects. In all groups, the number of neurons decreased with age, but by roughly age 40 the average LC count among the three suicide and/or alcoholic groups was lower than among controls. The rate of LC neuron loss was greater among suicides than among controls, but the rate of loss among alcoholics who were at least 30 years old was the same as that among the controls. Our group of alcoholic suicides had counts that were statistically indistinguishable from those of suicides. Differences among groups appear to be most pronounced in the middle third of the LC. Further studies are needed to determine the mechanisms of noradrenergic neuron loss and whether it is associated with an underlying major depression in suicide victims, or acquired after a period of excessive alcohol consumption.