1. Is there change in intelligence quotient in chronically ill schizophrenia patients? A longitudinal study in twins discordant for schizophrenia
- Author
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René S. Kahn, Ron Hijman, Rachel G.H. Brans, Anna M. Hedman, N.E.M. van Haren, G.C.M. van Baal, and Hilleke E. Hulshoff Pol
- Subjects
Adult ,Male ,Longitudinal study ,Pediatrics ,medicine.medical_specialty ,Psychometrics ,Intelligence ,Disease ,Cohort Studies ,Young Adult ,Reference Values ,Diseases in Twins ,Twins, Dizygotic ,medicine ,Humans ,Longitudinal Studies ,Gene–environment interaction ,Young adult ,Applied Psychology ,Intelligence quotient ,business.industry ,Wechsler Scales ,Twins, Monozygotic ,Middle Aged ,medicine.disease ,Psychiatry and Mental health ,Schizophrenia ,Chronic Disease ,Female ,Gene-Environment Interaction ,Schizophrenic Psychology ,business ,Follow-Up Studies ,Cohort study - Abstract
BackgroundIntellectual deficits are commonly found in schizophrenia patients. These intellectual deficits have been found to be heritable. However, whether the intellectual deficits change over time and, if so, whether the change is related with an increased genetic risk for the disease are not known.MethodWe investigated change of intelligence quotient (IQ) in a twin sample of chronically ill schizophrenia patients, the discordant co-twins and healthy controls during a follow-up period of 5 years. A total of 52 twins completed two IQ assessments: nine patients [three monozygotic (MZ) and six dizygotic (DZ)], 10 unaffected co-twins (three MZ and seven DZ) and 33 healthy control twins (21 MZ and 12 DZ).ResultsA significant interaction effect over time was found between IQ measurement and illness (F=4.22, df=1, pt=2.06, pt=−2.32, pt=−0.49, p=0.63).ConclusionsPatients with schizophrenia in the chronic phase of the disease, but not the discordant co-twins, show a lack of increase in IQ, which is probably due to environmental (non-genetic) factors related to the disease.
- Published
- 2012