Einar Kringlen

High interrater reliability for the structured clinical interview for DSM-III-R axis I (SCID-I)

The interrater reliability of the Structured Clinical Interview for DSM‐III‐R (SCID) was studied. Fifty‐four audiotaped SCID interviews were rated independently by 3 raters. The highest interrater agreements were observed for schizophrenia (0.94), major depressive disorder (0.93), dysthymia (0.88), generalized anxiety disorder (0.95), panic disorder (0.88), alcohol use disorder (0.96) and other psychoactive substance use disorder (0.85). The remaining diagnoses of mood and anxiety disorders obtained acceptable interrater agreement (0.70–0.80), with an exception for obsessive‐compulsive disorder (0.40). The poorest agreement was obtained for somatoform disorders (– 0.03). Lack of hierarchy in DSM‐III‐R allows for multiple Axis I diagnoses. Interrater reliability for multiple diagnoses was tested. Agreement was generally good for combinations of 2 diagnoses, and poorer when 3 diagnoses were combined. Our findings confirm that SCID yields highly reliable diagnoses. SCID is recommended for research on mental disorders.

A twin study of DSM-III-R anxiety disorders

The prevalence of anxiety disorders was studied in a sample of 20 monozygotic (MZ) and 29 dizygotic (DZ) co‐twins of anxiety disorder probands. A comparison group of co‐twins of 12 MZ and 20 DZ twin probands with other non‐psychotic mental disorders was also studied. All subjects were personally interviewed with the Structured Clinical Interview for DSM‐III‐R Axis I (SCID‐I). Panic disorder was significantly more prevalent in co‐twins of panic probands. Generalized anxiety disorder (GAD) was more prevalent in co‐twins of GAD probands with a history of mood disorder (NS). Post‐traumatic stress disorder was significantly more prevalent in co‐twins of anxiety probands and was more prevalent in MZ than in DZ co‐twins. The prevalences of social and simple phobia were equal in co‐twins of anxiety and comparison probands. For both panic disorder and generalized anxiety disorder the MZ:DZ concordance ratio was more than 2:1. The results support the hypothesis of a genetic contribution in the etiology of panic disorder, generalized anxiety disorder and post‐traumatic stress disorder. The hypothesis that simple and social phobia are mainly caused by environmental experiences was also supported.

Twin concordance for DSM-III-R schizophrenia

The monozygotic (MZ)/dizygotic (DZ) concordance rates for schizophrenia and the relationship between schizophrenia and schizophrenic spectrum disorders were studied in a sample of 31 MZ and 28 DZ schizophrenic probands and their co‐twins. All subjects were personally interviewed with structured diagnostic instruments and classified according to DSM‐III‐R criteria. The concordance rates of 48% for MZ twins and 4% for DZ twins indicate a genetic transmission of DSM‐III‐R schizophrenia. In addition to the schizophrenic co‐twins, 3 MZ co‐twins had a nonaffective psychotic disorder, thus supporting the hypothesis that genes are involved in the development of Axis I schizophrenic spectrum disorders. Schizotypal and paranoid personality disorders were observed in both MZ and DZ co‐twins. These disorders may be familially related to schizophrenia, but a genetic relationship was not confirmed for the Axis II spectrum disorders. A substantial number of MZ co‐twins of schizophrenic probands had no mental disorder.

Quality of life and anxiety disorders: A population study

The study of quality of life has increased in importance in the area of mental disorders during the last decade. The aim of the present study was to investigate the effect of specific anxiety disorders on specific quality of life indicators in the common population. More than 2000 individuals between 18 and 65 years old were studied by means of structured interviews. The results showed that social phobia and panic disorder within the past year and lifetime, and generalized anxiety disorder within the past year, had an independent effect on quality of life when controlling for a number of sociodemographic variables, somatic health, and other DSM-III-R Axis I mental disorders. Specific phobias and obsessive compulsive disorder had only a small effect, and agoraphobia showed no effect. The effect was strongest for self-realization and contact with friends, but anxiety disorders also influenced subjective well-being, social support, negative life events, contact with family of origin, and neighborhood quality.

Schizotypal personality disorder inside and outside the schizophrenic spectrum.

The concept of schizotypal personality disorder has been heavily discussed since its introduction into the official classification of mental disorders in DSM-III. The aim of this study was to investigate the difference between schizotypal personality disorder within and outside the genetic spectrum of schizophrenia. Schizotypals with and without schizophrenic cotwins and first-degree relatives were compared, with individuals with other mental disorders and no mental disorders as controls. It appeared that only inadequate rapport and odd communication were more pronounced among schizotypals within, compared to schizotypals outside the schizophrenic spectrum. Schizotypals outside the schizophrenic spectrum, however, scored higher than schizotypals inside the schizophrenic spectrum on ideas of reference, suspiciousness, paranoia, social anxiety, self-damaging acts, chronic anger, free-floating anxiety and sensitivity to rejection. Interestingly, the four last features are seldom observed among schizotypals inside the schizophrenic spectrum. Monozygotic non-schizophrenic cotwins of schizophrenics score high on inadequate rapport, odd communication, social isolation and delusions/hallucinations. Monozygotic non-schizophrenic cotwins of schizotypals outside the schizophrenic genetic spectrum score high on illusions, depersonalization, derealization and magical thinking. Negative schizotypal features appear to be inside the schizophrenic spectrum, while positive borderline-like features are outside having another genetic endowment.

Back–neck pain and symptoms of anxiety and depression: a population-based twin study

BACKGROUND Clinical and epidemiological studies have shown an association between anxiety and depression and pain in the back and neck. The nature of this relationship is not clear. This study aimed to investigate the extent to which common genetic and environmental aetiological factors contribute to the covariance between symptoms of anxiety and depression and back-neck pain. METHODS Measures of back-neck pain and symptoms of anxiety and depression were part of a self-report questionnaire sent in 1992 to twins born in Norway between 1967 and 1974 (3996 pairs). Structural equation modelling was applied to determine to what extent back-neck pain and symptoms of anxiety and depression share genetic and environmental liability factors. RESULTS The phenotypic correlation between symptoms of anxiety and depression and back-neck pain was 0.31. Individual differences in both anxiety and depression and back-neck pain were best accounted for by additive genetic and individual environmental factors. Heritability estimates were 0.53 and 0.30 respectively. For back-neck pain, however, a model specifying only shared- and individual environmental effects could not be rejected. Bivariate analyses revealed that the correlation between back-neck pain and symptoms of anxiety and depression was best explained by additive genetic and individual environmental factors. Genetic factors affecting both phenotypes accounted for 60% of the covariation. There were no significant sex differences. CONCLUSION The results support previous findings of a moderate association between back-neck pain and symptoms of anxiety and depression, and suggest that this association is primarily due to common genetic effects.

Twin studies in schizophrenia with special emphasis on concordance figures

Twin studies in schizophrenia have been reviewed with special emphasis on concordance rates in population-based investigations. Sources of error have been discussed with particular focus on sampling. The pair-wise concordance rates in schizophrenia are 30-40% in MZ and 5-10% in DZ, with somewhat higher rates for proband concordance. The findings from twin studies support the diathesis stress model in schizophrenia, and it is argued that the polygenic model gives the best explanation for the empirical findings.

Mental disorders in first-degree relatives of schizophrenics

A total 215 first‐degree relatives of 88 twin probands with schizophrenia, mood disorders and nonaffective psychoses were studied. The twins’ parents and siblings were personally interviewed with structured diagnostic instruments and diagnosed in accordance with DSM‐III‐R criteria. The first‐degree relatives were interviewed by interviewers who were blind to the twins’ diagnoses. Schizophrenia and schizotypal personality disorder were significantly more frequent in first‐degree relatives of schizophrenic twins. Respectively, anxiety and mood disorders were significantly more prevalent among the parents and siblings of probands with mood disorders. Schizophrenic spectrum disorders were significantly more common in the families of schizophrenic probands compared with relatives of mood disorder probands, thus confirming a relationship between schizophrenia and schizophrenic spectrum disorders. However, we cannot, based on our study, specify whether this relationship is caused by genetic or environmental factors.

SMOOTH PURSUIT EYE MOVEMENTS IN TWINS DISCORDANT FOR SCHIZOPHRENIA

IN A SERIES of studies we reported that between 65 and 80 % of schizophrenic patients have disordered pursuit eye movements, compared with about 15 “/;, in other psychiatric populations and 6 % in the normal population. Of equal interest was the finding that about 45-50 “/,; of first-degree relatives of the schizophrenics also showed the same kind of eye-tracking impairments, compared with a prevalence in the families of other psychotic patients that was no greater than that found in the normal population. 1,~ This association of disordered pursuit eye movements with schizophrenia and with members of the families of schizophrenics suggested that deviant pursuit eye movements may represent a genetic indicator of schizophrenia. This hypothesis would obtain confirmation if monzygotic (MZ) and dizygotic (DZ) twins who are discordant for schizophrenia were concordant for deviant eye tracking. This paper describes such a study. Smooth pursuit eye movements are those attendant upon following a moving target, and the speed of the target determines almost exactly the speed of the eyes. Rapid or saccadic movements are those that occur when fixation shifts, as when a person looks about a room from one object to another. In saccadic shifts, the eye can move at very rapid speeds, at times up to 600 degrees a second. In contrast, following movements break down into saccadic shifts if the target moves faster than about 40 degrees a second. A simple test of pursuit eye movements simply requires a subject to follow a pendulum. The pendulum, of course, oscillates at a continuously varying velocity, at first accelerating to a maximum and then decelerating to zero velocity. Electronystagmographic recording permits the investigator to obtain a permanent record of eye movements during the pursuit task.‘,2 In good pursuit eye movements the eyes should reproduce the sinusoidal wave form of the pendulum. Figure 1 shows four examples of pursuit movements. Normal eye tracking is represented in Figs la, lb. Deviations in eye tracking, such as those illustrated in Figs lc and Id are found in persons with some hemispheric and brain-stem lesions, multiple sclerosis, Parkinson’s disease, and some drug intoxications, particularly barbiturate and alcohol.3 In our studies we found that deviant eye tracking patterns in young schizophrenic patients occurred without the presence of organic disease and in a large number of their first-degree relatives the poor tracking occurred without either the presence of clinical schizophrenia or of organic pathology. Indeed, none of the relatives examined had visited a psychiatric facility for treatment for themselves and all were functioning quite adequately in the social

The heritability of common phobic fear: a twin study of a clinical sample.

The aim of this study was to investigate the genetic and environmental contribution to common phobic fears, and to relate the findings to contemporary theories about the etiology of common phobic fears. Self-reported common phobic fear was studied in a treatment sample of 23 monozygotic and 38 same-sex dizygotic twin pairs. Heritability of .47 was observed for common phobic fear of small animals and social fear, and a heritability of .30 in common agoraphobic fear. For common fear of nature phenomena and situational fear, the heritability was 0. The finding that common nature and situational fears were solely caused by environmental factors is in support of learning theory, whereas results for animal, social, and other common phobic fear are in support of an integrative theory of biological preparedness, learning history, and a cognitive style of fearful expectation.