Is Platelet Imipramine Binding Reduced in Depression

Although it has been suggested that decreased platelet imipramine binding may be a putative biological marker of depressive illness, a number of studies have not con/irmed this finding, including a recent muiticenter investigation by the World Health Organization (Mellerup and Langer 1990). We performed a meta-analysis of published reports on imipramine binding in groups of depressed and healthy control subjects and found that there was a highly significant decrease in B,~,,~ (maximal binding) values in the depressed subject groups, which was even greater among those who had been free of medication for 4 weeks at the time of investigation. This finding remained highly significant even when only high affinity binding studies (Ka <1 nmol/L) were considerecL although the absolute size of this decrease was smaller.