Differing patterns of electrodermal and finger pulse responsivity in schizophrenia and depression

Non-response of the autonomic orienting response (OR), as indexed jointly by deficient skin conductance (SCR) and finger pulse amplitude responding (FPAR), has been shown to occur with excessive frequency in the schizophrenic population. The present study is an attempt to replicate earlier evidence that SCR-OR and FPAR-OR, when measured in concert, could distinguish schizophrenic from depressed patients (Bernstein et al. 1988). This issue is critical of the question of diagnostic specificity of OR non-responding, since reduced SCR has been found repeatedly in depression as well as in schizophrenia. We examined SCR and FPAR concurrently in 69 schizophrenic, 45 depressed, and 67 normal subjects. SCR non-responding was more frequent in both schizophrenics and depressives than in normal controls, while only the schizophrenics displayed excessive FPAR non-responding. Moreover, among SCR non-responders, concordant OR non-responding--defined as non-responding indexed simultaneously in both the SCR and FPAR components--was most common in the schizophrenic sample. These findings support our previous conclusion that OR non-responding in depression, may have distinct peripheral origins. Our results also suggest that measuring multiple biochemically distinct components of the OR may be more sound methodologically than obtaining a single channel recording.