Inter-correlations between Cloninger's temperament dimensions-- a meta-analysis.

The Temperament and Character Inventory (TCI) was developed to measure the following temperament dimensions: novelty seeking (NS), harm avoidance (HA), reward dependence (RD) and persistence (P). These four dimensions of temperament were originally proposed to be independent of one another. In this study the inter-relationships between the dimensions were studied with meta-analytic techniques. We also studied the effects of sociodemographic factors (location of the study, mean age and gender distribution) on correlations between temperament dimensions. We searched studies on healthy (non-clinical) populations that used the TCI (version 9), and that had a required sample size of at least 100. The search resulted in 16 articles. The resulted pooled correlation coefficient was medium level between NS and HA (-0.27). Correlations were small for HA-P (-0.20), NS-P (-0.14), NS-RD (0.10), RD-P (0.05) and HA-RD (0.04). In meta-regression, the correlation NS-P was significantly affected by the location of the study (Asian/other) and by the gender distribution of the sample. In the HA-P correlation, the mean age of the sample affected the correlation. In conclusion, we found a medium level negative correlation between NS and HA; other correlations between the dimensions were small. These findings mainly support Cloninger's theory of independent dimensions.

Non-participation may bias the results of a psychiatric survey: an analysis from the survey including magnetic resonance imaging within the Northern Finland 1966 Birth Cohort.

OBJECTIVE: A major reason for limited validity of research is non-participation. Subjects with severe mental illness tend to cumulate in the group of non-participants, causing selection bias. We tested the hypothesis that severe psychosis is linked to non-participation in a field survey including magnetic resonance imaging (MRI) of the brain, psychiatric interviews and cognitive testing among subjects with psychosis. Furthermore, we wanted to explore other associative factors expected to affect non-participation. METHODS: Members of the Northern Finland 1966 Birth Cohort with a lifetime diagnosis of psychosis (N = 145) were invited to participate in the survey conducted in 1999-2001. Non-participation was determined by refusal or loss of contact. Data were gathered in earlier phases of the follow-up study or using register data. RESULTS: Ninety-one (63%) subjects attended the study. Compared to participants, non-participants were more often patients with schizophrenia and had more psychiatric hospitalisations, they had more positive psychosis symptoms during their illness course and they were more often on disability pension. Married subjects participated more often than those who were not married. CONCLUSION: This study suggests that among subjects with psychosis, particularly those subjects who have the most severe course of illness are less willing to participate. This may lead to biased estimates when studying subjects with severe mental disorders.

Sex differences in Cloninger's temperament dimensions--a meta-analysis.

There have been many comparisons between men and women on psychological characteristics and personality. The Tridimensional Personality Questionnaire and Temperament and Character Inventory developed by Cloninger are used to measure the following temperament dimensions: novelty seeking, harm avoidance, reward dependence, and persistence. Studies using these scales in healthy (nonclinical) populations have reported varying results on sex differences, but there is no meta-analysis of the topic. In this study, meta-analytic methods were used to estimate sex differences in these temperament dimensions and to study the effect of mean age of the sample and location of the study (Asia/other) on possible differences. Studies on healthy populations were systematically collected; the required minimum sample size was 100. The search resulted in 32 eligible studies. Consequently, women scored higher in reward dependence (pooled effect size; Cohen's d = -0.63; z test, P value < .001) and harm avoidance (d = -0.33; P < .001). There were no differences in novelty seeking (d = -0.04; P = .29) or in persistence (d = -0.02; P = .62). The sex difference in reward dependence was significantly smaller in Asian studies. This study was the first one to pool studies on sex differences in Cloninger's temperament dimensions. Women scored consistently higher in harm avoidance in the studies included. Together with similar sex difference found in related traits (eg, depression), this finding supports the validity of this temperament dimension. The given data on sex differences should be taken into account in future studies using these instruments.

Socio-demographic and clinical predictors of occupational status in schizophrenic psychoses--follow-up within the Northern Finland 1966 Birth Cohort.

We studied occupational status of persons with schizophrenic psychoses by age 34 in a longitudinal population-based cohort and predicted which demographic and illness-related factors could support the patients to maintain their occupational capacity. Subjects of the Northern Finland 1966 Birth Cohort with the diagnosis of DSM-III-R schizophrenic psychoses (n=113) by the year 1997 were followed until the end of year 2000. Various illness and socio-demographic factors at the time of onset of illness were used as predictors. At the end of the follow-up time 50 (44%) of patients were not pensioned and 22 (20%) were also working at least half of the time during year 2000. After adjusting for gender, being unemployed at onset, educational level and proportion of time spent in psychiatric hospitals, those who were married or cohabiting at the time of onset of illness were less often on pension than those who were single (OR 6.51; 95% CI 1.83-23.12). Thus, nearly half of the patients with schizophrenic psychoses were not pensioned after an average 10 years follow-up. Based on our findings, those who were single at time of their onset of illness probably need most support to retain their contacts to work life.

Risk factors for schizophrenia. Follow-up data from the Northern Finland 1966 Birth Cohort Study.

This paper updates single risk factors identified by the Northern Finland 1966 Birth Cohort Study up to the end of year 2001 or age 34. Impaired performance (e.g., delayed motor or intellectual development) or adverse exposures (e.g., pregnancy and birth complications, central nervous system diseases) are associated with an increased risk for schizophrenia. However, upper social class girls and clever schoolboys also have an increased risk to develop schizophrenia, contrasted to their peers. Individuals who subsequently develop schizophrenia follow a developmental trajectory that partly and subtly differs from that of the general population; this trajectory lacks flexibility and responsiveness compared to control subjects, at least in the early stages. We propose a descriptive, lifespan, multilevel systems model on the development and course of schizophrenia.

Patterns of psychiatric hospitalizations in schizophrenic psychoses within the Northern Finland 1966 Birth Cohort.

We report patterns of hospitalization in schizophrenic psychoses by age 34 in a longitudinal population-based cohort. We test the predictive ability of various demographic and illness-related variables on patterns of hospitalization, with a special focus on the length of the first psychiatric hospitalization. All living subjects of the Northern Finland 1966 Birth Cohort with DSM-III-R schizophrenia (n=88) and other schizophrenia spectrum cases (n=27) by the year 1997 in the Finnish Hospital Discharge Register were followed for an average of 10.5 years. Measures of psychiatric hospitalization included time to re-hospitalization (as continuous and as re-hospitalization within 2 years) and the number of hospital episodes. Length of the first hospitalization, other illness-related and various socio-demographic predictors were used to predict hospitalization patterns. After adjusting for gender, age at first admission and number of hospital days a short (1-14 days) first hospitalization (reference >30 days; adjusted odds ratio 6.39; 95% CI 2.00-20.41) and familial risk of psychosis (OR 3.36; 1.09-10.39) predicted re-hospitalization within 2 years. A short first hospitalization also predicted frequent psychiatric admissions defined as the first three admissions within 3 years (OR 13.77; 3.92-48.36). A short first hospitalization was linked to increased risk of re-hospitalizations. Although short hospitalization is recommended by several guidelines, there may be a group of patients with schizophrenic psychoses in which too short a hospitalization may lead to inadequate treatment response.

Predictors of schizophrenia: evidence from the Northern Finland 1966 Birth Cohort and other sources.

BACKGROUND: Subtle motor, emotional, cognitive and behavioural abnormalities are often present in apparently healthy individuals who later develop schizophrenia, suggesting that some aspects of causation are established before overt psychosis. AIMS: To outline the development of schizophrenia. METHOD: We drew on evidence from The Northern Finland 1966 Birth Cohort supplemented by selected findings from other relevant literature. RESULTS: The main known risk factors in development of schizophrenia are genetic causes, pregnancy and delivery complications, slow neuromotor development, and deviant cognitive and academic performance. However, their effect size and predictive power are small. CONCLUSIONS: No powerful risk factor, premorbid sign or risk indicator has been identified that is useful for the prediction of schizophrenia in the general population.

Predictors of schizophrenia--a review.

Schizophrenia is an aetiologically heterogeneous syndrome that usually becomes overtly manifest in adolescence and early adulthood, but in many cases subtle impairments in neurointegrative function are present from birth; hence it is considered to be a disorder with a neurodevelopmental component. The strongest risk factor that has been identified is familial risk with genetic loading. Other risk factors include pregnancy and delivery complications, infections during pregnancy, disturbances of early neuromotor and cognitive development and heavy cannabis use in adolescence. Unfortunately, to date it has not been possible to utilize the predictors of the disorder that have been identified in primary preventative interventions in a general population. However, some authors have claimed that in future it might be possible to reduce the risk for developing schizophrenia through general health policy. In clinical settings, it is helpful to map out possible early risk factors, at least familial risk for psychosis, especially in child, adolescent and young adult mental patients. Furthermore, in the future we may have predictive models combining data from genetic factors for schizophrenia, antenatal risk factors, childhood and adolescent development and clinical symptomatology, as well as brain structural and functional abnormalities.

Recovery from schizophrenic psychoses within the northern Finland 1966 Birth Cohort.

BACKGROUND: Because of widely disparate findings from follow-up studies, the likelihood of recovery from schizophrenia remains controversial. We report the extent of recovery from schizophrenia in a population-based cohort. METHOD: Subjects with psychotic disorders were recruited from the Northern Finland 1966 Birth Cohort. Of the 91 subjects who agreed to participate, 59 were diagnosed with schizophrenia and 12 were diagnosed with schizophrenia spectrum disorders (schizophreniform psychosis, schizoaffective or delusional disorder) by DSM-III-R criteria. Diagnoses were established by interviewing the subjects, checking the Finnish Hospital Discharge Register, and reviewing their medical records. To assess recovery, we used the Clinical Global Impressions; the Positive and Negative Syndrome Scale; the Social and Occupational Functioning Assessment Scale; and information about psychiatric hospitalizations, use of antipsychotic medication, and occupational status. RESULTS: Only 1 subject (1.7%) with DSM-III-R schizophrenia and 3 subjects (25%) with schizophrenia spectrum disorders fully recovered; 1 schizophrenia subject (1.7%) and 2 schizophrenia spectrum subjects (16.7%) experienced partial recovery. CONCLUSION: The data indicate that, at least until age 35, complete recovery from schizophrenia is rare, and the prognosis for the disorder is far more serious than suggested by some follow-up studies.

Links between creativity and mental disorder.

A link between mental disorder and decreased ability is commonly assumed, but evidence to the contrary also exists. In reviewing any association between creativity and mental disorder, our aim is not only to update the literature but also to include an epidemiological and theoretical discussion of the topic. For literature retrieval, we used Medline, PsycINFO, and manual literature searches. Studies are numerous: most are empirical, many having methodological difficulties and variations in definitions and concepts. There is little consensus. However, some trends are apparent. We found 13 major case series (over 100 cases), case-control studies, or population-based studies, with valid, reliable measures of mental disorders. The results of all but one of these studies supported the association, at least when concerning particular groups of mental disorders; the findings were somewhat unclear in two studies. Most of the remainder that are not included in our more detailed examination also show a fragile association between creativity and mental disorder, but the link is not apparent for all groups of mental disorders or for all forms of creativity. In conclusion, evidence exists to support some form of association between creativity and mental disorder, but the direction of any causal link remains obscure.

Developmental precursors of psychosis.

Subtle developmental (motor, emotional, cognitive, and behavioral) abnormalities are often present in apparently healthy individuals who later develop psychosis, suggesting that some aspects of causation are established before overt psychosis. These impairments may restrict information processing and social achievements years before manifesting psychosis. The main known risk factors in the development of schizophrenic psychosis are genetic factors, pregnancy and delivery complications, slow neuromotor development, and deviant cognitive and academic performance. However, their effect size and predictive power are small. Developmental precursors are not necessarily specific to schizophrenia, but also common to other psychotic disorders. No powerful risk factor, premorbid sign, or risk indicator has been identified that is useful for prediction of psychoses in the general population.