Pre-morbid IQ in mental disorders: a Danish draft-board study of 7486 psychiatric patients

TY - JOUR

T1 - Pre-morbid IQ in mental disorders: a Danish draft-board study of 7486 psychiatric patients

AU - Urfer-Parnas, A

AU - Lykke Mortensen, E

AU - Sæbye, D

AU - Parnas, J

PY - 2010/4

Y1 - 2010/4

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 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 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

SN - 0033-2917

VL - 40

SP - 547

EP - 556

JO - Psychological Medicine

JF - Psychological Medicine

IS - 4

ER -