Schizophrenia is associated with altered orienting activity: Depression with electrodermal (cholinergic?) deficit and normal orienting response.

Abstract

The import of a recent consensus that a distinctive subgroup of schizophrenics is marked by nonreactivity of the orienting response (OR) to innocuous stimuli has been made ambiguous by reports of similar nonreactivity among depressives. To test this, we studied 50 schizophrenics (14 drug free), 50 depressives (20 drug free), and 50 normal controls. Stimuli were 1000 Hz (60 dB) or 2000 Hz (58 dB) 1-s tones delivered either to the left or right ear. A subsample of each group was told they need do nothing during tone presentations (habituation series); other subsamples had to press a pedal for each designated target signal (left ear, right ear, 1000 Hz, 2000 Hz), ignoring all nontarget tones. Skin conductance response (SCR) and finger pulse volume (FPV) analyses are reported. As in previous work, schizophrenics showed high nonresponding in the habituation series, consistent in both SCR and FPV, and they showed normalizing in both to target signals. Depressives were equally nonresponsive during the habituation series in SCR, but did not normalize to target signals and showed normal FPV response during both the habituation and target series. Whereas schizophrenic dysfunction reflected OR change, that of depressives seemed to reflect Cholinergic deficit but intact OR. This was associated with high retardation and low agitation ratings, but not with degree of depression on Hamilton or Zung scales. In addition, 10 largely remitted depressives showed the same pattern as did patients currently in a major depressive episode.The orienting response (OR), a system facilitating information intake, consists of a range of autonomic, skeletal muscle, and electroencephalogram (EEG) components including skin conductance response (SCR), finger-pulse volume constriction (FPV), pupillary dilation, alpha blockade, general decreases in muscle activity (Sokolov, 1963), cardiac deceleration (Graham & Clifton, 1966), as well as the P300 component of the evoked potential (Nash & Peralme, 1986;Roth, 1973). Recent study has linked the OR to the allocation of a limited-capacity central processor operating only after activation of an automatic, parallel-processing, preattentional system (Dawson, Schell, Beers, & Kelly, 1982;Ohman, 1979). Despite its relatively late onset in the information-processing sequence, OR-associated capacity allocation can occur quickly. For example, Filion, Dawson, and Schell (1986) recently reported a latency within 150 ms.The OR thus provides an index of important attentional processes-one that is physiologically denned. Both features are

Habituation and Sensitization Processes in Depressive Disorders

“…Thus, the lower SCL, OR and SCOR conductance amplitudes are, the larger the scores in BDI, STAI-E and STAI-R. Some authors have observed similar results [34,42], but other studies have not detected any correlation [26,38,43,44]. In the present research, the depressive sample displayed high scores in STAI which would be able to reflect elevated anxiety.…”

Examining electrodermal hyporeactivity as a marker of externalizing psychopathology: A twin study

“…It is possible that electrodermal hyporeactivity reflects the operation of underlying mechanisms that are shared with other disorders besides those in the externalizing spectrum. Reduced orienting reactivity and accelerated rates of habituation have previously been linked to diverse disorders ranging from schizophrenia to mood disorders (Bernstein et al, 1988; Iacono, Ficken, & Beiser, 1999). Indeed, reduced SCR frequency may be an indicator of general psychopathology severity rather than a psychophysiological marker associated with a specific type of mental illness (Wahlund, Sorman, Gavazzeni, Fischer, & Kristiansson, 2010).…”

Electrodermal Activity

“…3.4.2.2). An interesting hypothesis on the difference between nonresponding in depressives and schizophrenics has been developed by Bernstein et al (1988) who found similar patterns in SCR nonresponding but differences in finger pulse volume between both groups. Since depressives showed intact ORs in the finger pulse amplitude measure, their deficit in electrodermal responsivity may be due to their possible deficit in peripheral cholinergic mediation, thus having a different origin as in schizophrenics.…”