TY - JOUR
T1 - Change in IQ in schizophrenia patients and their siblings
T2 - a controlled longitudinal study
AU - Genetic Risk and Outcome of Psychosis (G.R.O.U.P.)
AU - Van Haren, N. E. M.
AU - Van Dam, D. S.
AU - Stellato, R. K.
AU - Alizadeh, Behrooz Z.
AU - van Amelsvoort, Therese
AU - Bartels-Velthuis, Agna A.
AU - van Beveren, Nico J.
AU - Bruggeman, Richard
AU - Cahn, Wiepke
AU - de Haan, Lieuwe
AU - Delespaul, Philippe
AU - Meijer, Carin J.
AU - Myin-Germeys, Inez
AU - Kahn, Rene S.
AU - Schirmbeck, Frederike
AU - Simons, Claudia J. P.
AU - van Os, Jim
AU - van Winkel, Ruud
AU - Luykx, Jurjen J.
PY - 2019/11
Y1 - 2019/11
N2 - Background. Lower intelligence quotient (IQ) has frequently been reported in patients with schizophrenia. However, it is unclear whether IQ declines (further) after illness onset and what the familial contribution is to this change. Therefore, we investigate IQ changes during the course of illness in patients with non-affective psychosis, their siblings and controls.Methods. Data are part of the longitudinal Genetic Risk and Outcome of Psychosis (GROUP) study in the Netherlands and Belgium. Participants underwent three measurements, each approximately 3 years apart. A total of 1022 patients with non-affective psychosis [illness duration: 4.34 (S.D. = 4.50) years], 977 of their siblings, and 565 controls had at least one measure of IQ (estimated from four subtests of the WAIS-III).Results. At baseline, IQ was significantly lower in patients (IQ = 97.8) and siblings (IQ = 108.2; p<0.0001) than in controls (IQ = 113.0; p<0.0001), and in patients as compared with siblings (p<0.0001). Over time, IQ increased in all groups. In siblings, improvement in IQ was significantly more pronounced (+0.7 points/year) than in patients (+03 points/year; p<0.0001) and controls (+0.3 points/year; p<0.0001). IQ increase was not significantly correlated with improvement in (sub)clinical outcome in any of the groups.Conclusions. During the first 10 years of the illness, IQ increases to a similar (and subtle) extent in a relatively high-functioning group of schizophrenia patients and controls, despite the lower IQ in patients at baseline. In addition, the siblings' IQ was intermediate at baseline, but over time the increase in IQ was more pronounced.
AB - Background. Lower intelligence quotient (IQ) has frequently been reported in patients with schizophrenia. However, it is unclear whether IQ declines (further) after illness onset and what the familial contribution is to this change. Therefore, we investigate IQ changes during the course of illness in patients with non-affective psychosis, their siblings and controls.Methods. Data are part of the longitudinal Genetic Risk and Outcome of Psychosis (GROUP) study in the Netherlands and Belgium. Participants underwent three measurements, each approximately 3 years apart. A total of 1022 patients with non-affective psychosis [illness duration: 4.34 (S.D. = 4.50) years], 977 of their siblings, and 565 controls had at least one measure of IQ (estimated from four subtests of the WAIS-III).Results. At baseline, IQ was significantly lower in patients (IQ = 97.8) and siblings (IQ = 108.2; p<0.0001) than in controls (IQ = 113.0; p<0.0001), and in patients as compared with siblings (p<0.0001). Over time, IQ increased in all groups. In siblings, improvement in IQ was significantly more pronounced (+0.7 points/year) than in patients (+03 points/year; p<0.0001) and controls (+0.3 points/year; p<0.0001). IQ increase was not significantly correlated with improvement in (sub)clinical outcome in any of the groups.Conclusions. During the first 10 years of the illness, IQ increases to a similar (and subtle) extent in a relatively high-functioning group of schizophrenia patients and controls, despite the lower IQ in patients at baseline. In addition, the siblings' IQ was intermediate at baseline, but over time the increase in IQ was more pronounced.
KW - Intelligence
KW - longitudinal
KW - outcome
KW - schizophrenia
KW - siblings
KW - 1ST EPISODE PSYCHOSIS
KW - 1ST-EPISODE SCHIZOPHRENIA
KW - COGNITIVE-DEVELOPMENT
KW - RISK
KW - INTELLIGENCE
KW - ONSET
KW - NEUROCOGNITION
KW - METAANALYSIS
KW - PERFORMANCE
KW - DECLINE
U2 - 10.1017/S0033291718003537
DO - 10.1017/S0033291718003537
M3 - Article
SN - 0033-2917
VL - 49
SP - 2573
EP - 2581
JO - Psychological Medicine
JF - Psychological Medicine
IS - 15
ER -