TY - JOUR
T1 - Pre-morbid IQ in mental disorders: a Danish draft-board study of 7486 psychiatric patients
AU - Parnas, Annik Francoise Urfer
AU - Lykke Mortensen, E
AU - Sæbye, Ditte
AU - Parnas, J
PY - 2010
Y1 - 2010
N2 - BACKGROUND: Longitudinal studies indicate that future schizophrenia patients exhibit lower IQ than healthy controls. Recent studies suggest that future patients with other mental illnesses obtain lower pre-morbid IQ. The aims of this study were to compare pre-morbid IQ among five diagnostic categories and normal controls, to examine the distribution of pre-morbid IQ, and to investigate the relationship between pre-morbid IQ and risk of mental illness. METHOD: A total of 7486 individuals hospitalized with psychiatric disease and 20 531 controls. IQ was measured at the draft board and hospital diagnoses [schizophrenia (Sz), non-schizophrenic, non-affective psychoses (NSAP), affective (AD), personality (PD) and neurotic/stress disorders (ND)] were followed up to ages 43-54 years. Individuals hospitalized < or = 1 year after appearing before the draft board were excluded. RESULTS: All future patients obtained significantly lower pre-morbid IQ than controls (3-7 IQ points), AD had the highest IQ and PD the lowest. In each diagnostic category, decreasing IQ was associated with an increasing risk of becoming a patient [odds ratios (ORs) 0.5-2.5 over the full IQ spectrum]. IQ distributions was nearly normal and uni-modal. CONCLUSIONS: IQ deficits in each diagnostic category may reflect different functional patterns and temporal vicissitudes of the specific pathogenetic processes involved in different mental disorders.
AB - BACKGROUND: Longitudinal studies indicate that future schizophrenia patients exhibit lower IQ than healthy controls. Recent studies suggest that future patients with other mental illnesses obtain lower pre-morbid IQ. The aims of this study were to compare pre-morbid IQ among five diagnostic categories and normal controls, to examine the distribution of pre-morbid IQ, and to investigate the relationship between pre-morbid IQ and risk of mental illness. METHOD: A total of 7486 individuals hospitalized with psychiatric disease and 20 531 controls. IQ was measured at the draft board and hospital diagnoses [schizophrenia (Sz), non-schizophrenic, non-affective psychoses (NSAP), affective (AD), personality (PD) and neurotic/stress disorders (ND)] were followed up to ages 43-54 years. Individuals hospitalized < or = 1 year after appearing before the draft board were excluded. RESULTS: All future patients obtained significantly lower pre-morbid IQ than controls (3-7 IQ points), AD had the highest IQ and PD the lowest. In each diagnostic category, decreasing IQ was associated with an increasing risk of becoming a patient [odds ratios (ORs) 0.5-2.5 over the full IQ spectrum]. IQ distributions was nearly normal and uni-modal. CONCLUSIONS: IQ deficits in each diagnostic category may reflect different functional patterns and temporal vicissitudes of the specific pathogenetic processes involved in different mental disorders.
U2 - 10.1017/S0033291709990754
DO - 10.1017/S0033291709990754
M3 - Journal article
C2 - 19656427
VL - 40
SP - 547
EP - 556
JO - Psychological Medicine
JF - Psychological Medicine
SN - 0033-2917
IS - 4
ER -