Lauren Asnis

The Schedule for Schizotypal Personalities (SSP): A diagnostic interview for schizotypal features

The validity and reproducibility of psychiatric diagnosis are crucial to psychiatric research. To establish confidence in assigning schizotypal features, three paradigms estimating the reliability of a new instrument, the Schedule for Schizotypal personalities (SSP), were tested. The first paradigm considered joint, but independent evaluations made by two raters simultaneously. The second paradigm assessed evaluations on different occasions, with a mean interim time of 5.9 months (test-retest procedure). Both reliability paradigms demonstrated high levels of agreement for all of the scaled items. Ninety percent of the intraclass correlation coefficients were 0.80 or better for the joint evaluations, and 70% were 0.80 or better for the test-retest evaluation. The third paradigm measured the reliability of DSM-III Schizotypal Personality Disorder. The kappa value for measuring diagnostic agreement was 0.88. The authors recommend the use of the SSP as an interview schedule and discuss the implications of their findings for genetic and biological research of schizophrenia spectrum disorders.

Assortative mating in affective disorders

Assortative mating was determined in 170 spouses of patients with major affective illness (bipolar and unipolar). An increase in affective disorders was found in both wives of affected men and husbands of affected women. The data suggest that assortative mating is present in the familial transmission of affective disorder.

Age-of-Onset in Schizophrenia and Schizotypal Disorders

Age-of-onset data were gathered on 93 chronic schizophrenic probands and 57 affected (mainly schizotypal) siblings. 55% of affected individuals were ill before age 20 and 14% had their onset before age 14. The risk period for schizophrenia and schizotypal personality disorders terminated at age 40. Age-of-onset did not distinguish paranoid from nonparanoid schizophrenics, or definite from probable schizotypal personalities. Schizophrenic and schizotypal subjects were similar in their age-of-onset patterns. Sex effect on age-of-onset was not present. A square-root normal distribution gave the best fit to the data. The implications of these findings for schizophrenia research were discussed.

Diagnostic overlap in schizophrenia research: relation to outcome predictors and family history.

Five sets of criteria for the diagnosis of schizophrenia were compared on 47 hospitalized patients who fit New York Research Diagnostic Criteria (RDC) for chronic schizophrenia. The other diagnostic systems used were the Flexible System. Feighner Criteria, New Haven Schizophrenia Index (NHSI), and Taylor-Abrams (TA) Criteria. The NSHI, the broadest system examined, fit all of the patients studied. In contrast, only 30 patients (63% of the sample) were diagnosed schizophrenic using TA Criteria. When the Strauss-Carpenter prognostic scale was used, patients who fit TA Criteria for schizophrenia did not differ in the prognostic scores from the remainder of the sample. In addition, the two groups did not differ in the familial rate of schizophrenia spectrum disorders. The usefulness of narrow versus broad diagnostic criteria in schizophrenia research is discussed.