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Cited by 102Child and Adolescent Psychosocial and Emotional DevelopmentGenetic Associations and EpidemiologyAnxiety, Depression, Psychometrics, Treatment, Cognitive Processes

Monozygotic twins discordant for major depression: a preliminary exploration of the role of environmental experiences in the aetiology and course of illness

KENDLER, KENNETH S., GARDNER, CHARLES O.·2001·Psychological Medicine
DOI 10.1017/s0033291701003622
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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.

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Crossref · 10.1017/s0033291701003622

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  • All of the SLEs examined (such as assault, job loss or sexual abuse) have been implicated as risk factors for depression in genetically informative studies.

    “All of these SLEs have been implicated as risk factors for depression in genetically informative studies (Kendler et al., 1995, 2000; Kendler & Aggen, 2014; Kendler & Gardner, 2001; Kendler, Karkowski, & Prescott, 1999a).”

    From Stressful life events increase the risk of major depressive episodes: A population-based twin study (2023) · cites this paper as Kendler & Gardner, 2001

  • Using a similar design as in the current study, Kendler and Gardner (2001) found that MZ twins with a history of depression reported higher rates of job loss compared with non-depressed co-twins.

    “Using a similar design as in the current study, Kendler and Gardner (2001) found that MZ twins with a history of depression reported higher rates of job loss compared with non-depressed co-twins.”

    From Stressful life events increase the risk of major depressive episodes: A population-based twin study (2023) · cites this paper as Kendler & Gardner, 2001

  • Causal influence on the risk of depression has been suggested for a number of specific SLEs included in the current study, such as assault, sexual abuse, and romantic problems and job loss.

    “Causal influence on the risk of depression has been suggested for a number of specific SLEs included in the current study, such as assault (Kendler et al., 1999a, 2010), sexual abuse (Kendler et al., 2000; Kendler & Aggen, 2014; Nelson et al., 2002), and romantic problems and job loss (Kendler & Gardner, 2001).”

    From Stressful life events increase the risk of major depressive episodes: A population-based twin study (2023) · cites this paper as Kendler & Gardner, 2001

  • Findings from some previous genetically informative studies indicate that the association between economic SLEs and depression may be at least in part causal.

    “Although the inflated within-pair estimates in our study are difficult to interpret, findings from some previous genetically informative studies indicate that this association may be at least in part causal.”

    From Stressful life events increase the risk of major depressive episodes: A population-based twin study (2023) · cites this paper as Kendler & Gardner, 2001

  • These findings were replicated in individuals in the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders.

    “These important findings were replicated in individuals in the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders, a cohort of 9000 adult Caucasian twins.”

    From Epigenetic mechanisms of major depression: Targeting neuronal plasticity (2018) · cites this paper as [97]

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Authors
KENDLER, K. S., & GARDNER, C. O.
Affiliations
Virginia Commonwealth University (US)
ORCID
KENDLER, KENNETH S.
Venue
Psychological Medicine
Publisher
Cambridge University Press (CUP)
Published
2001-04
Volume
31
Issue
3
Pages
411-423
ISSN
  • 0033-2917 (ISSN-L)
  • 1469-8978
DOI
10.1017/s0033291701003622
OpenAlex
W2132589140
Cited by
102
References
32
Citations by year
2026: 1 · 2025: 1 · 2024: 1 · 2023: 2 · 2022: 3 · 2021: 3 · 2018: 1 · 2017: 5 · 2016: 6 · 2015: 6 · 2014: 8 · 2013: 8 · 2012: 4
FWCI
9.32
Type
journal article
Language
en
Open access
closed
Licence
www.cambridge.org/core/terms (unspecified, 11 d)
Locations
  • Psychological Medicine (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health (5k05mh001277-05)
  • National Institute on Alcohol Abuse and Alcoholism (R01AA009095, AA-09095)
  • National Institute of Mental Health (MH-01277, R01MH040828, MH 40828)
Topics
  • Social Sciences › Psychology › Clinical Psychology › Child and Adolescent Psychosocial and Emotional Development
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetic Associations and Epidemiology
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Anxiety, Depression, Psychometrics, Treatment, Cognitive Processes
Keywords
major depressive disorder, monozygotic twins, discordant twins, environmental risk factors, parent-child conflict, optimism, life events, financial hardship, phobia, nicotine dependence, divorce, childhood anxiety, interpersonal problems, etiology of depression, genetic versus environmental factors, co-twin control
MeSH terms
Adult, Alcohol Drinking, Major Depressive Disorder, Environment, Female, Health Status, Humans, Parent-Child Relations, Personality, Psychiatric Status Rating Scales, Risk Factors, Self Concept, Severity of Illness Index, Twins, Monozygotic, Cluster Analysis, Marital Status, Substance-Related Disorders

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