Skin conductance. A potentially sensitive and specific marker for depression.

Resting skin conductance levels (SCLs) were measured in 50 patients with unipolar depression, in 71 controls (control group 1), and in 334 "stressed" normal controls (control group 2) who were first parents of newborns. The depressed group had significantly (p less than .00001) lower SCLs than did either control group, but the two control groups did not differ from each other. For women a criterion of SCL less than 3.0 micronho/cm2 yielded a sensitivity of 95% (SE 4.4%) and a specificity of 91% (SE 5.0%) for Control Group 1. For males a criterion of SCL less than 4.8 yielded a sensitivity of 93% (SE 4.9%) and a specificity of 89% (SE 5.0%) for control group 1. There was no significant difference in SCL between drug-free and medicated patients. SCL was abnormally low in all depression subtypes.