LONGITUDINAL STUDY OF TEMPERAMENT IN INDIVIDUALS WITH PSYCHOTIC DISORDERS AND HEALTHY CONTROLS

1. LONGITUDINAL STUDY OF TEMPERAMENT IN INDIVIDUALS WITH PSYCHOTIC DISORDERS AND HEALTHY CONTROLS Jouko Miettunen (1), Eka Roivainen (2), Juha Veijola (1,3), Antti Alaräisänen (1), Matti Isohanni (1), Erika Jääskeläinen (1) 1) Department of Psychiatry, Oulu University and Oulu University Hospital, Oulu, Finland, 2) Oulu Deaconess Institute, Oulu, Finland, 3) Institute of Health Sciences, University of Oulu, Oulu, Finland Objective: The Temperament and Character Inventory (TCI) developed by Cloninger is used to measure novelty seeking (NS), harm avoidance (HA), reward dependence RD), and persistence (P). Temperament is a possible endophenotype for psychiatric disorders and may also relate e.g. treatment adherence, and social and clinical outcome of the illness. There are not many longitudinal studies on temperament, especially stability of temperament among individuals with psychosis is unknown. We evaluated stability of temperament and infrequency in answering in individuals with psychotic disorders and healthy control subjects. Methods: As part of the 31-year follow-up survey of the prospective population based Northern Finland 1966 Birth Cohort, the temperament part (107 items) of TCI and an Infrequency Scale (12 items indicating random or fake answers, maximum 12 points) were collected from a large sample of individuals (n=4943). A case-control subsample of psychotic individuals (n=28), with onset age before the first follow-up (mean 25.0 years), and healthy controls (n=116) were given these scales again in a second follow-up at the age of 43. • Results: • A high rate of invalid responding was observed in psychotic individuals at age 43 years. When taking into account both follow-ups, 39% had either too many missing or infrequent answers; corresponding percentage among controls was 15% (see Table 1). These individuals were excluded in longitudinal comparisons. • The 31-year and 43-year temperament scores correlated largely among controls (n=99) (Pearson’s r: NS 0.70, HA .65, RD .56, P .57), whereas correlations among psychotic individuals (n=17) were weaker (NS .38, HA .51, RD .30, P .51). See Table 2. • At the 31-year follow-up cases scored in average 18.3 in NS, 20.3 in HA, 14.2 in RD, and 3.5 in P; whereas controls scored 20.9, 13.2, 14.3, and 4.3, respectively. Difference was statistically significant in HA (effect size d = 1.49, p<.001). At age 43, mean scores (NS, HA, RD, P) were for cases 16.8, 19.4, 14.5, and 3.8 and for controls 19.6, 12.9, 14.3, and 4.2, respectively. Differences were significant in NS (d = 0.77, p=.004) and HA (d = 1.38, p<.001). Table 1. Number of missing answers and infrequent answers at 31- and 43- year follow-up studies of the Table 2. Correlations between 31- and 43-year studies in different temperament dimensions in psychotic (cases) and non-psychotic (controls) individuals. Conclusion: Individuals with psychotic disorders may exhibit overendorsement of nonsensical items on infrequency scales. Harm avoidance and persistence are quite stable also in psychoses. Novelty seeking and reward dependence had poor stability in psychoses, which may be explained by the clinical status of the individuals. Despite individual differences in scoring between the two follow-ups among cases; differences between cases and controls remained stable even after a long follow-up. Correspondence: Jouko Miettunen P.O.Box. 5000, FIN-90014 University of Oulu, Finland Email. jouko.miettunen@oulu.fi Fax. +358-8-336 169 Tel. +358-40-7167261 Acknowledgements: This study has been supported by the Academy of Finland, the European Commission (EURO-BLCS, Framework 5 award QLG1-CT-2000-01643), the NARSAD: the Brain and Behavior Research Fund, the Finnish Medical Association, the Sigrid Jusélius Foundation, The Finnish Medical Society Duodecim Oulu, DAAD (German Academic Exchange Service), and US National Institutes of Health (NIMH) (5R01MH63706:02).