Skin conductance: a potentially sensitive test for depression.

The mean resting skin conductance level (SCL) in 31 inpatients with major unipolar depression was 2.63 mumho/cm2 +/- SD 1.41 compared to 7.81 mumho/cm2 +/- SD 3.0 in the control group. The best criterion below which an SCL could be considered abnormal was 4.3 mumho/cm2 with a resulting sensitivity of 87% and specificity of 89%. There was a significant difference in SCL between males and females but none between drug-free and medicated patients. SCL was abnormal in all depression subtypes. The SCL may represent a biological final common pathway in depression and may prove to be a very effective diagnostic test for depression.