CONTEXT: Consistent evidence indicates that some, but not most, patients with schizophrenia have below-average intelligence years before they manifest psychosis. However, it is not clear whether this below-average premorbid intelligence is stable or progressive. OBJECTIVE: To examine whether increased risk for schizophrenia is associated with declining intellectual performance from childhood through adolescence. DESIGN: Historical cohort study of an entire population using record linkage for psychiatric hospitalization during an 8- to 17-year follow-up period. SETTING: Mandatory assessment by the draft board of Israeli conscripts. PARTICIPANTS: Population-based cohort of 555 326 adolescents born in Israel. Data were available on 4 intelligence subtests as well as on reading and spelling abilities and on behavioral and psychosocial variables. A regression-based approach was used to assess the discrepancy between actual IQ at age 17 years and estimated IQ during childhood based on reading and spelling abilities. MAIN OUTCOME MEASURES: Hospitalization for schizophrenia (as per the International Statistical Classification of Diseases, 10th Revision criteria). RESULTS: Lower-than-expected IQ at age 17 years was associated with increased risk for later hospitalization for schizophrenia. Results were held after controlling for potential confounders. For 75% of patients with schizophrenia with low actual IQ (<85) at age 17 years and for 23% of patients with actual IQ within the normal range (> or =85), actual IQ was 10 or more points lower than expected. Lower-than-expected IQ was not associated with bipolar disorder or with depression or anxiety disorder. CONCLUSIONS: Indirect evidence suggests that intellectual deterioration from childhood through adolescence is associated with increased risk for schizophrenia. Despite within-normal-range premorbid IQ scores, apparently healthy adolescents who will later manifest schizophrenia nevertheless have intellectual decline.
CONTEXT: Consistent evidence indicates that some, but not most, patients with schizophrenia have below-average intelligence years before they manifest psychosis. However, it is not clear whether this below-average premorbid intelligence is stable or progressive. OBJECTIVE: To examine whether increased risk for schizophrenia is associated with declining intellectual performance from childhood through adolescence. DESIGN: Historical cohort study of an entire population using record linkage for psychiatric hospitalization during an 8- to 17-year follow-up period. SETTING: Mandatory assessment by the draft board of Israeli conscripts. PARTICIPANTS: Population-based cohort of 555 326 adolescents born in Israel. Data were available on 4 intelligence subtests as well as on reading and spelling abilities and on behavioral and psychosocial variables. A regression-based approach was used to assess the discrepancy between actual IQ at age 17 years and estimated IQ during childhood based on reading and spelling abilities. MAIN OUTCOME MEASURES: Hospitalization for schizophrenia (as per the International Statistical Classification of Diseases, 10th Revision criteria). RESULTS: Lower-than-expected IQ at age 17 years was associated with increased risk for later hospitalization for schizophrenia. Results were held after controlling for potential confounders. For 75% of patients with schizophrenia with low actual IQ (<85) at age 17 years and for 23% of patients with actual IQ within the normal range (> or =85), actual IQ was 10 or more points lower than expected. Lower-than-expected IQ was not associated with bipolar disorder or with depression or anxiety disorder. CONCLUSIONS: Indirect evidence suggests that intellectual deterioration from childhood through adolescence is associated with increased risk for schizophrenia. Despite within-normal-range premorbid IQ scores, apparently healthy adolescents who will later manifest schizophrenia nevertheless have intellectual decline.
Authors: Cynthia B Solot; Tyler M Moore; Terrence Blaine Crowley; Marsha Gerdes; Edward Moss; Daniel E McGinn; Beverly S Emanuel; Elaine H Zackai; Sean Gallagher; Monica E Calkins; Kosha Ruparel; Ruben C Gur; Donna M McDonald-McGinn; Raquel E Gur Journal: Am J Med Genet B Neuropsychiatr Genet Date: 2020-07-27 Impact factor: 3.568
Authors: Annick Urfer Parnas; Lennart Jansson; Peter Handest; Jan Nielsen; Ditte Sæbye; Josef Parnas Journal: World Psychiatry Date: 2007-02 Impact factor: 49.548
Authors: Max Lam; W David Hill; Joey W Trampush; Jin Yu; Emma Knowles; Gail Davies; Eli Stahl; Laura Huckins; David C Liewald; Srdjan Djurovic; Ingrid Melle; Kjetil Sundet; Andrea Christoforou; Ivar Reinvang; Pamela DeRosse; Astri J Lundervold; Vidar M Steen; Thomas Espeseth; Katri Räikkönen; Elisabeth Widen; Aarno Palotie; Johan G Eriksson; Ina Giegling; Bettina Konte; Annette M Hartmann; Panos Roussos; Stella Giakoumaki; Katherine E Burdick; Antony Payton; William Ollier; Ornit Chiba-Falek; Deborah K Attix; Anna C Need; Elizabeth T Cirulli; Aristotle N Voineskos; Nikos C Stefanis; Dimitrios Avramopoulos; Alex Hatzimanolis; Dan E Arking; Nikolaos Smyrnis; Robert M Bilder; Nelson A Freimer; Tyrone D Cannon; Edythe London; Russell A Poldrack; Fred W Sabb; Eliza Congdon; Emily Drabant Conley; Matthew A Scult; Dwight Dickinson; Richard E Straub; Gary Donohoe; Derek Morris; Aiden Corvin; Michael Gill; Ahmad R Hariri; Daniel R Weinberger; Neil Pendleton; Panos Bitsios; Dan Rujescu; Jari Lahti; Stephanie Le Hellard; Matthew C Keller; Ole A Andreassen; Ian J Deary; David C Glahn; Anil K Malhotra; Todd Lencz Journal: Am J Hum Genet Date: 2019-08-01 Impact factor: 11.025
Authors: Katherine E Burdick; Terry E Goldberg; Birgit Funke; John A Bates; Todd Lencz; Raju Kucherlapati; Anil K Malhotra Journal: Schizophr Res Date: 2006-10-30 Impact factor: 4.939
Authors: Ingo Frommann; Ralf Pukrop; Jürgen Brinkmeyer; Andreas Bechdolf; Stephan Ruhrmann; Julia Berning; Petra Decker; Michael Riedel; Hans-Jürgen Möller; Wolfgang Wölwer; Wolfgang Gaebel; Joachim Klosterkötter; Wolfgang Maier; Michael Wagner Journal: Schizophr Bull Date: 2010-01-06 Impact factor: 9.306