Blood cells as biological trait markers in affective disorders

Data are reviewed on platelet monoamine oxidase activity, red blood cell/plasma lithium ratio, and tritiated imipramine binding to platelet membranes as trait markers for affective disorders. The results of various studies are not in agreement. Differences in methodological procedure are probably central to such discrepancies. At the present time, no single biological abnormality of blood cells has proved to be a trait marker for affective disorders; thus their use to identify vulnerability to mood disorders or predict favourable response to pharmacological treatment appears to be premature.