Psychophysiologic markers of psychopathology: A review.

Abstract

Research criteria for the identification and evaluation of a characteristic as a genetic marker of the functional psychoses are specified. Each of five psychophysiologic variables (smoothpursuit eye tracking, nailfold capillary visibility, electrodermal nonresponding, reducing/ augmenting of the visual evoked potential, and resting EEG) is reviewed for its marker potential. All five characteristics have been found to hold promise as genetic markers for schizophrenia and/or the major affective disorders. Some suggestions for future research are made.

Electrodermal Activity

“…However, it has to be kept in mind that electrodermal nonresponding is not specific for schizophrenia, since a large number of patients with unipolar and bipolar affective disorders (Sect. 3.4.1.3) also show this characteristic, raising the possibility that electrodermal nonresponding reflects genetic liability for several forms of psychopathology (Iacono, 1985). Such a possibility had been investigated by Iacono, Ficken, and Beiser (1999) in an investigation with 135 first-episode psychiatric patients (schizophrenics and other 244 A possible expansion of experimental possibilities for investigating electrodermal hypo-or hyperresponsivity in schizophrenics as compared to normal controls had been demonstrated by Lim et al (1999b), using Lim et al's (1997 mathematical solution for evaluating overlapping EDRs during short-ISI paradigms, which also offers a possibility to combine EDA with ERP recordings (e.g., Roth, Goodale, & Pfefferbaum, 1991).…”

“…However, Hare (1978a) in his above- 215 Bilateral recordings with Ag/AgCl electrodes of 4.5 mm diameter, filled with 0.5% KCl in agar-agar cream, using 0.5 V constant voltage. Amplitude criterion: 0.05 mS. 216 Although schizophrenia has been the domain for electrodermal nonresponding, this phenomenon is clearly not specific to schizophrenia (Iacono, 1985;see Sect. 3.4.2.2).…”

Toward an Integrated Theory of Schizotaxia, Schizotypy, and Schizophrenia

“…One does not demand a quasi-infallible marker trait, although the Super Bootstraps Theorem (Meehl, 1973b the proof see, 1990b; Meehl 6k Golden, 1982) will enable us to find such a marker should it exist. For a clarifying analysis of the loose concept marker, distinguishing susceptibility ("risk," vulnerabil ity) markers as either (a) nongenetic, (b) merely gene pool correlated, (c) genetically linked, hence familial, or (d) pleiotropic indicators of the pathogene, see Iacono (1985). I always employ the term "indicator" to denote type d, because we are concerned only with pleiotropic markers when testing the dominant schizotaxia theory.…”

Eye movement dysfunction in first-degree relatives of patients with schizophrenia: A meta-analytic evaluation of candidate endophenotypes

“…To be considered an endophenotype of a disorder, a characteristic should have several properties that together indicate that it is a measurable, reliable manifestation of genetic risk for that disorder (e.g., Gottesman & Gould, 2003; Iacono, 1983, 1985, 1998; Iacono & Grove, 1993). One of the primary reasons that EMD has been of such interest is that several lines of evidence converge in support of a genetic influence on EMD, thereby implying that EMD will assist in gene identification.…”

“…The purpose of the current investigation was to evaluate the endophenotype candidacy of smooth pursuit, saccade and fixation EMD based on evidence from family and genetic studies. Although several previous reviews have addressed the candidacy of SPEMD as an endophenotype of schizophrenia (Clementz & Sweeney, 1990; Erlenmeyer-Kimling & Cornblatt, 1987; Holzman, 1992; Iacono, 1983, 1985, 1988, 1998; Iacono & Grove, 1993; Keefe, Silverman, Siever, & Cornblatt, 1991; Keri & Janka, 2004; Lee & Williams, 2000; Levy, Holzman, Matthysse, & Mendell, 1993; Levy, Holzman, Matthysse, & Mendell, 1994; Lipton, Levy, Holzman, & Levin, 1983), the present review contributes in three ways to cumulative knowledge on the candidacy of several forms of eye movement dysfunction (EMD) as endophenotypes. First, in contrast to most previous reviews that have narratively summarized the literature, where possible, we employed meta-analysis, which confers several advantages.…”