Impaired attention is commonly observed among schizophrenia patients and those at genetic risk for the disease. This article reviews over 40 studies that used various versions of the Continuous Performance Test (CPT) as the primary measure of attention. These studies of normal subjects, affected patients, and various at-risk populations demonstrate that the CPT is a psychometrically sound procedure that consistently discriminates affected patients from controls. Sufficiently difficult versions of this task have also demonstrated that impaired attention is (1) evident in schizophrenia patients regardless of clinical state, (2) detectable before illness onset, (3) apparently heritable, (4) specific--in terms of distinct profile patterns--to schizophrenia, and (5) predictive of later behavioral disturbances in susceptible individuals. Selected studies are also discussed that examine the role of attentional deficit in the pathophysiology of schizophrenia and its potential consequences for personality development. With respect to pathophysiology, preliminary data suggest that subcortical brain dysfunction has an important role in the attentional deficits tapped by the CPT. With respect to personality, an association between chronically impaired attention and deficient social skills has been found. It is concluded that the CPT is a cost-effective measure of the attentional deficit commonly found in affected schizophrenia subjects and those at risk for the disorder, and is therefore a potentially valuable screening device for preventive intervention programs.

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Impaired Attention, Genetics, and the Pathophysiology of Schizophrenia

Assessment of Personality and Psychopathology: Psychodiagnosis Case Formulation Behavioural Predication Treatment Planning Neuropsychological Assessment Methods and Recommendations for Making Judgements Clinical Judgement Computers and Judgement Improving Psychological Assessment.

Studying the Clinician: Judgment Research and Psychological Assessment

We present an overview of self-report scales for measuring schizotypy and a review of factor-analytical studies of these scales. These studies show that schizotypy is a multidimensional construct consisting of three or four factors. Positive Schizotypy, Negative Schizotypy, Nonconformity, and possibly Social Anxiety/Cognitive Disorganization. Clinical and external validation studies provide support for the construct validity of the Positive Schizotypy and Negative Schizotypy factors, but as yet fail to support the Nonconformity and Social Anxiety/Cognitive Disorganization factors. In accordance with this multidimensional structure, the scales for measuring schizotypy can be classified as factor-specific scales. We consider the striking similarities between the multidimensionality of schizotypal traits and the multidimensionality of schizophrenic symptoms. We also look at the similarities and differences between schizotypy and normal personality traits. Some practical and theoretical implications of these relationships are discussed.

The Multidimensionality of Schizotypy

The longitudinal followup strategy in high-risk research is being increasingly complemented by the use of psychosis-pro neness scales to select subjects for study who might be vulnerable to schizophrenia and who show differences on laboratory measures that could act as endophenotypic markers for use in genetic investigations. Three types of experimental paradigm have been adopted, drawn from cognitive psychology, psychophysiology, and the neuropsychology of hemisphere function. Results adopting each of these approaches are examined, alongside recent factor-analytic evidence that psychosis-proneness scales currently in use tap up to four different components that map onto the clinical heterogeneity of schizophrenia (and possibly other forms of psychosis). No one of these components clearly emerges as, or points to, a single indicator of risk, though some aspect of neurocognitiv e functioning seems a likely candidate. Even so, it is argued, the clinical expression of vulnerability must be due to a convergence in an individual of several components of risk since individually (and notably so for "susceptibility to positive symptoms") they are very common in the healthy population. In evaluating the evidence, attention is drawn to two crucially different ways that investigators in schizophrenia research have construed the notion of continuity (1) as subclinical defect (or forme fruste of disease) having varying expression or (2) as biologically based personality dimensions that simultaneously describe the dispositions to aberrations of function leading to degree of illness. It is noted that the model of continuity chosen can significantly shape the way the results of risk research are interpreted and the theories of psychosis to which they give rise. Schizophrenia Bulletin, 20(1): 151-168, 1994.

Single Indicator of Risk for Schizophrenia: Probable Fact or Likely Myth?

The psychometric high-risk strategy represents a useful methodologic adjunct to the traditional genetic high-risk research approach in the study of the etiology and development of schizophrenia. During the past 15 years, considerable research activity has focused on psychometrically identified individuals hypothesized to be en route to schizophrenia (i.e., putative schizotypes). The Perceptual Aberration Scale (PAS) has figured prominently in such prediction-oriented psychometric high-risk work. This report examines research using the PAS completed since 1987 that has established the instrument as a valid index for detecting liability for schizophrenia (or schizotypy) and as, arguably, the schizotypy index of choice for research. These results are presented and interpreted in light of Meehl's theoretical framework of schizotypy. Other measures of and assessment devices for schizotypy (schizophrenia-related liability) are identified. Of these other measures, the Chapmans' Magical Ideation Scale and the schizophrenia liability index of Moldin and colleagues are particularly well established. Methodologic suggestions for future psychometric high-risk and other work using objective measures of schizotypic psychopathology are offered. It is strongly recommended that future studies of schizotypy (or those in the planning stages, relying on psychometric detection methods use multiple psychometric indices to tap schizotypy or use a psychometric index in association with other promising biobehavioral markers of schizophrenia liability (e.g., sustained attentional deficits, eye movement dysfunction) for maximum efficiency in both location and definition of schizotypes.

Psychometric High-risk Paradigm, Perceptual Aberrations, and Schizotypy: An Update

The genetic analysis of schizophrenia would be facilitated by identification of a heritable correlate of liability Deviance on an index of Minnesota Multiphasic Personality Inventory (MMPI) signs is associated with the disease phenotype; the familial aggregation and mode of transmission of this continuous psychometric indicator have yet to be established In this paper, we examine the indicator through commingling analysis and segregation analysis with both the mixed and unified models on 65 nuclear families containing 211 normal individuals Evidence for a high degree of familiality is found Analysis of untransformed data under a conditional likelihood provides evidence for Mendelian transmission of a major gene with commingling of two distributions The frequency of the "high index score" allele is 015, with the gene accounting for 31% of the total population variance; such a locus would be relevant to the study of psychopathology as 28% of the population would carry at least one deviant allele When power-transformed scores are used to eliminate skewness, there is evidence for one distribution and it is not possible to distinguish single gene from multifactorial (polygenic or cultural) inheritance While our findings regarding mode of transmission must be interpreted cautiously and confirmation of a single locus requires further study, demonstration of familiality warrants continued investigation of the index as an indicator of liability for schizophrenia

C. F. Sing

Papers

Transmission of a psychometric indicator for liability to schizophrenia in normal families.