K S Kendler1, C O Gardner. 1. Department of Psychiatry, Medical College of Virginia of Virginia Commonwealth University and Virginia Institute for Psychiatric and Behavioral Genetics, Richmond, USA.
Abstract
BACKGROUND: Genetic effects upon behaviour are pervasive. To what extent are the many correlates of major depression (MD) due to individual-specific environmental experiences versus genetic factors correlated with risk for MD? METHODS: From a population-based twin registry, we identified 72 female monozygotic pairs discordant for a lifetime history of MD and compared the affected and unaffected members on a wide range of putative correlates of MD. RESULTS: The affected twin differed from her unaffected co-twin on many variables, eight of which were maximally discriminating: (i) maternal protectiveness; (ii) conflictual parent-child relationship; (iii) low optimism; (iv) current stressful life events; (v) financial difficulties and a history of (vi) phobia, (vii) nicotine dependence; and (viii) divorce. A cluster analysis suggested three 'environmental pathways' to MD characterized by: (i) childhood vulnerability and anxiety; (ii) acting-out and demoralization; and (iii) interpersonal difficulties. CONCLUSION: Important precursors and sequelae of MD originate in environmental experiences unique to the individual and are not mediated through genetic factors or family-of-origin effects. Such environmental factors cause pervasive differences in monozygotic twins discordant for MD, especially in the areas of interpersonal difficulties, psychopathology, social problems and self-concept. These findings should be interpreted in the context of possible retrospective recall bias and the difficulty of distinguishing risk factors from sequelae in co-twin-control studies.
BACKGROUND: Genetic effects upon behaviour are pervasive. To what extent are the many correlates of major depression (MD) due to individual-specific environmental experiences versus genetic factors correlated with risk for MD? METHODS: From a population-based twin registry, we identified 72 female monozygotic pairs discordant for a lifetime history of MD and compared the affected and unaffected members on a wide range of putative correlates of MD. RESULTS: The affected twin differed from her unaffected co-twin on many variables, eight of which were maximally discriminating: (i) maternal protectiveness; (ii) conflictual parent-child relationship; (iii) low optimism; (iv) current stressful life events; (v) financial difficulties and a history of (vi) phobia, (vii) nicotine dependence; and (viii) divorce. A cluster analysis suggested three 'environmental pathways' to MD characterized by: (i) childhood vulnerability and anxiety; (ii) acting-out and demoralization; and (iii) interpersonal difficulties. CONCLUSION: Important precursors and sequelae of MD originate in environmental experiences unique to the individual and are not mediated through genetic factors or family-of-origin effects. Such environmental factors cause pervasive differences in monozygotic twins discordant for MD, especially in the areas of interpersonal difficulties, psychopathology, social problems and self-concept. These findings should be interpreted in the context of possible retrospective recall bias and the difficulty of distinguishing risk factors from sequelae in co-twin-control studies.
Authors: Jennifer L Cecilione; Lance M Rappaport; Shannon E Hahn; Audrey E Anderson; Laura E Hazlett; Jason R Burchett; Ashlee A Moore; Jeanne E Savage; John M Hettema; Roxann Roberson-Nay Journal: Twin Res Hum Genet Date: 2018-02 Impact factor: 1.587
Authors: Jinying Zhao; Arshed A Quyyumi; Riyaz Patel; A Maziar Zafari; Emir Veledar; Stephen Onufrak; Lucy H Shallenberger; Linda Jones; Viola Vaccarino Journal: Psychosom Med Date: 2009-07-21 Impact factor: 4.312