Department of Psychiatry, Virginia Institute for Psychiatric and Behavioral Genetics, Richmond, Virginia, USA
Correspondence: Dr. C. M. Bulik, Department of Psychiatry, Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, PO Box 980126, Richmond, VA, 23298-0126, USA. Tel: 001 804 828 8129; fax: 001 804 828 1471; e-mail: cbulik{at}hsc.vcu.edu
Declaration of interest None. Funding detailed in Acknowledgements.
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Aims To explore the risk associated with features of CSA and examine whether specific associations exist between particular profiles of CSA and the development of specific syndromes.
Method In a population-based sample of adult female twins, we used logistic regression to explore the association between features of CSA (reported by the twin and her co-twin) and lifetime major depression, generalised anxiety disorder, bulimia nervosa, panic disorder and alcohol and drug dependence.
Results In univariate and stepwise multiple regressions, patterns of predictors differed, although not significantly, across diagnoses. Greater risk was associated with attempted or completed intercourse, the use of force or threats, abuse by a relative, and a negative response by someone who was told about the abuse. Similar patterns were observed with co-twin reports.
Conclusions Specific features of CSA differentially increase risk of later psychopathology; however, there do not appear to be unique predictive relationships between features of CSA and the emergence of specific psychiatric disorders.
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
METHOD |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Clinically experienced interviewers were trained for 40 hours and received regularly scheduled review sessions over the course of the study. Psychiatric and substance use disorders were diagnosed by personal interview using an adaptation of the Structured Clinical Interview for DSMIIIR (SCID) (Spitzer et al, 1988) and DSMIIIR criteria (American Psychiatric Association, 1987) with two exceptions. First, a 1-month rather than 6-month minimum duration of illness for generalised anxiety disorder (GAD) was used (Kendler et al, 1992a). Second, diagnostic hierarchies were not used. Our assessment of drug dependence individually examined seven substance classes: cannabis, sedatives, stimulants, cocaine, opiates, hallucinogens and other. Although we collected information on the lifetime diagnosis of phobic disorders in this sample, we do not report those here because the early onset of many of the phobias (Kendler et al, 1992b) makes a causal interpretation of observed associations with CSA problematic.
A number of psychiatric and substance use disorders were assessed multiple times in these twins. In these analyses, we utilised lifetime diagnoses of major depression, GAD and alcohol and drug dependence as assessed at the fourth interview. Lifetime panic disorder and bulimia nervosa were assessed only at the earlier interviews (Waves 1 and 3) and so those diagnoses were used here. Further details of the diagnostic algorithms and diagnostic reliability appear in the literature (Kendler et al, 1991, 1992a, c, d, 1993; Kendler & Prescott, 1999).
Our Wave 2 interview asked the twins whether they would be willing to answer questions about CSA and, if so, by which method they would prefer this information to be gathered. Only 0.8% of the women said they would not cooperate with such a survey. Of the 1337 twins who stated a clear preference on mode of assessment, 108 (8.1%) preferred face-to-face interview, 229 (17.1%) a phone interview and 1000 (74.8%) a postal questionnaire. Therefore, we assessed CSA by postal questionnaire as part of the Wave 4 assessment.
Definition of CSA
Our assessment was based on the questionnaire developed by Mullen and
colleagues (Martin et al,
1993). The precise wording of our initial item was:
"Before you were 16, did any adult, or any other person older than yourself, involve you in any unwanted incidents like:
- inviting or requesting you to do something sexual;
- kissing or hugging you in a sexual way;
- touching or fondling your private parts;
- showing their sex organs to you;
- making you touch them in a sexual way;
- attempting or having sexual intercourse."
In this report, we include the 412 women who were classified as having experienced broad CSA, which includes a positive response to any of the above items.
Definitions of specific CSA-related predictors
The predictor variables that we used were: (a) age at time of first
abuse/intercourse (a dichotomous variable including attempted or completed
intercourse v. other forms of abuse); (b) the number of perpetrators
(one v. more than one); (c) age of perpetrator; (d) gender of
perpetrator (male v. female or both); (e) whether the perpetrator was
a relative (biological or step) or nonrelative; (f) the use of force or
threats; and (g) a seven-point scale reflecting how much the incident affected
the victim at the time. For those individuals who did report the abuse, we
created a variable called negative response, which reflected
whether the person she told did not believe, did not support, or punished her.
Finally, for those individuals who did report, we coded whether reporting put
a stop to the abuse.
Co-twin report
For a subset of predictor variables, we also had co-twin report on the
experiences of CSA in her twin. The variables that were available from co-twin
report were: intercourse (a dichotomous variable including attempted or
completed intercourse v. other forms of abuse), number of
perpetrators (one v. more than one), gender of perpetrator (male
v. female or both), whether perpetrator was a relative v.
non-relative, the use of force or threats.
Analyses
We examined the association between specific features of CSA and individual
psychiatric and substance use disorders using univariate logistic regression.
To correct for the correlated structure of the data (i.e. twin pairs), we
utilised the GEE option as operationalised in the SAS routine GENMOD (SAS
Institute, 1989,
1996). Odds ratios and their
associated confidence intervals (CIs) were obtained. To examine the relation
between specific features of CSA and comorbidity, we predicted, in logistic
regression, the risk for having two or more of the six individual diagnoses
(Kendler et al,
2000). We then conducted a series of stepwise multiple regressions
to examine the relative importance of the various features of CSA in
predicting the different diagnostic outcomes. For these analyses, we set the
criteria for entry and retention in the regression equation at 0.05.
In order to determine whether the odds ratios differed significantly across
the six diagnostic categories, we computed two logistic regression one
which estimated the regression coefficients separately for each diagnostic
category and one which estimated one common regression coefficient. We then
compared the difference between the two models using the 2 log likelihood as a
2 goodness-of-fit test. This allowed us to determine whether
there was a significant improvement in fit when separately estimating the
regression coefficients. No improvement in fit indicates the lack of
significant differences in the odds ratios across diagnostic categories.
We then calculated the agreement between twin and co-twin report of the features of CSA in those twins for whom reports were available from both twins. In addition, we conducted a series of logistic regressions using the same procedures outlined above using co-twin data as predictors of psychopathology in the abused twin.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
Univariate predictors of psychiatric and substance use disorders
Table 1 presents the odds
ratios and significance levels for the univariate logistic regressions
predicting the six disorders from the individual CSA characteristics. Although
results differed somewhat across diagnoses, a few patterns emerged. In
general, the presence of attempted or completed intercourse, the use of force
and threats, how strongly the victims were affected at the time, and a
negative response by someone they told were associated with increased risk of
spychopathology. Likewise, if telling someone effectively stopped the abuse,
reduced risk of psychopathology was observed.
Stepwise multiple regressions
In order to determine the most parsimonious set of predictor variables for
each diagnostic category, we performed a series of stepwise multiple
regressions including as predictor variables age at time of abuse, attempted
or completed intercourse, more than one perpetrator, age of perpetrator,
gender of perpetrator, abuse by a relative, whether forced or threatened, a
negative response, and whether reporting was effective in stopping the abuse.
In these analyses, no significant predictors were retained for alcohol
dependence.
For major depressive disorder, the only variable that remained in the
equation was whether intercourse was attempted or completed
(2=5.41, d.f.=1, P=0.02). For GAD, someone having a
negative response was the only variable that remained in the model
(
2=8.47, d.f.=1, P=0.004). For bulimia nervosa and
panic disorder the patterns of results were the same with the only significant
predictor being the use of force or threats
(
2BN=4.15, d.f.=1, P=0.04;
2Panic=7.53, d.f.=1, P=0.006). For drug
dependence, whether someone had a negative response (
2=9.83,
d.f.=1, P=0.002) remained in the regression equation. Finally, having
two or more diagnoses was significantly predicted by whether intercourse was
attempted or completed (
2=11.1, d.f.=1, P=0.0009) and
whether someone had had a negative response (
2=8.32, d.f.=1,
P=0.004).
Specificity of estimates
We then compared two separate logistic regression models to determine
whether there was a significant improvement in fit when separately estimating
the regression coefficients. The first model included all of the disorders in
a common regression coefficient and the second model included regression
coefficients estimated separately for each disorder. As can be seen in the
last column of Table 1, there
were no significant differences observed for any of the CSA variables between
the two regression models. The final summary odds ratios indicate
significantly elevated risk across all disorders associated with attempted or
completed intercourse, abuse by a relative, the use of force or threats, how
affected the victim was at the time, and negative response. There was a
significant protective effect when reporting was effective in stopping the
abuse.
Co-twin reports of features of CSA
Pairwise data were available on a variable number of twin pairs (between
100 and 226 individuals), depending on whether the co-twin responded to any
given CSA item regarding the experiences of her co-twin. For example, a
co-twin might have responded yes to a gate question regarding
whether her twin had ever been abused, but either not responded or responded
don't know to the more detailed questions about the perpetrator
and whether force was used. Don't know responses were coded as
missing. We calculated the agreement between twin and co-twin report on the
five variables that were common to the two assessments. Although most
associations between the twin and co-twin report were significant, the level
of agreement varied considerably (Table
2).
|
Finally, we calculated the odds ratios for the six disorders and comorbid condition (at least two of the six diagnoses) as predicted by the five variables in the co-twin report (data not shown). Given that the effective sample size for some of the comparisons was quite low, we were unable to conduct stepwise multiple regressions or explore the specificity of estimates as we had done with the twin self-report data. In this reduced set of predictors, however, attempted or completed intercourse and being forced or threatened were associated with the highest odds ratios for psychopathology in the twin. Abuse by a relative significantly increased risk only for GAD.
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
In the initial report from this series (Kendler et al, 2000), we reported that CSA increased the risk of developing later psychiatric disorders and that the effect appeared to be largely non-specific. In the present study, we narrowed our focus of inquiry by examining only those women who had experienced some form of sexual abuse and asking: (a) whether certain facets of CSA are more strongly associated with later psychopathology; and (b) whether a specific relationship can be observed between aspects of CSA and the later development of certain psychiatric syndromes.
Severity of abuse associated with greater risk for
psychopathology
Prior investigations suggest that severe abuse involving attempted or
completed penetration, longer duration of abuse, physical restraint or
violence and incestuous relationship with the abuser were associated with the
development of greater adjustment difficulties
(Mullen et al, 1993;
Romans et al, 1994,
1995;
Spaccarelli, 1994;
Spaccarelli & Kim, 1995;
Fergusson, 1996; Dinwiddie et al,
2000). Our findings confirmed these results. The risk of
psychopathology was greater in the present sample if intercourse was attempted
or completed, if the perpetrator was related to the victim, if force or
threats were used, and if someone the victim told about the abuse either did
not believe her, did not support her or punished her for the abuse. We
observed no increased risk of later psychopathology related to the age at
which an individual was first abused, the number of, or the gender of the
perpetrators.
Factors that are protective against the development of
psychopathology
Prior investigations have also shown that supportive family environments
can reduce the risk of negative outcomes in individuals who are victims of CSA
(Romans et al, 1995;
Spaccarelli & Kim, 1995). In the present study, one variable that conferred protection against the
development of psychiatric disorders in individuals who had been abused was
whether reporting was effective in putting an end to the abuse. Endorsement of
this variable indicates first that the victim chose to report and second, that
the individual to whom they reported was both supportive and active in ending
the abusive relationship. The second feature that served a protective effect
was how strongly the individual was affected at the time of the abuse. Being
less adversely affected at the time was protective; however, it is important
to note that the degree to which one is affected is likely to be a function of
several of the above measures that are indicators of severity of abuse, as
well as other pre-existing variables that contribute to positive mental health
such as strong family relationships or robust self-esteem.
This pattern of findings, together with previous studies, highlights the importance of not conceptualising CSA as a universally and homogeneously traumatic event, but rather recognising that both the nature and impact of CSA vary along several continua and that the long-term impact of CSA-related events is affected both by characteristics of the CSA as well as the presence of protective events such as the response of others to the reporting of the abuse experience.
Specificity of the effects of CSA
The issue of specificity of CSA has not been widely examined. Although
clinical studies of homogeneous populations (e.g. patients with eating
disorders or substance abuse) have consistently reported greater prevalence of
CSA in individuals with those disorders in comparison to the general
population (Briere & Runtz,
1988; Bushnell et al,
1992; Mullen et al,
1993; Romans et al,
1995; Fergusson et al,
1996; Wonderlich et
al, 1997), epidemiological studies suggest that CSA acts more
as a non-specific risk factor for psychiatric disorders, possibly by lowering
the threshold for expression of traits to which an individual is predisposed
by other genetic and/or environmental risk factors. Our initial report
(Kendler et al, 2000)
was consistent with a non-specific risk factor hypothesis in that the odds
ratios for psychiatric disorders varied somewhat in magnitude; however, the
confidence intervals were generally overlapping across diagnoses.
Are certain patterns of abuse uniquely predictive of specific
disorders?
Given that the effect of CSA appears to be non-specific, we embarked on a
more detailed analysis to address whether specific features of a CSA
experience might be uniquely predictive of the form of later psychopathology
(e.g. might abuse at a young age predispose to depression or anxiety whereas
abuse in the teenage years might increase the risk of developing a substance
use disorder?). Although the univariate analyses suggested differences in
patterns of predictors across diagnoses, there was no evidence that the odds
ratios for any of the CSA-related variables differed significantly across
diagnostic categories. Thus, not only does CSA taken as a global construct
appear to have a non-specific effect on the development of psychopathology,
but specific aspects of CSA do not appear to uniquely predict specific
psychiatric disorders.
These findings argue against the existence of a unified post-CSA syndrome with an identifiable symptom profile. Rather, CSA tends to function more as a non-specific risk factor that is associated with increased later risk for a range of psychiatric and substance use syndromes. The magnitude of risk can be modified by protective factors both intrinsic and extrinsic to the victim. Moreover, there is no evidence that certain patterns of abuse are uniquely associated with the later emergence of specific psychiatric syndromes.
Conversely, it is unlikely that the presence of various psychiatric disorders predisposed the victims to experience CSA as we have previously shown that the onset of depression and alcohol dependence occurred either during the same year or subsequent to the experience of CSA in 95.6 and 100% of the cases, respectively (Kendler et al, 2000).
Co-twin report
In a subset of twins, co-twin report was available regarding the abuse
experiences of their twin. In addition to missing reports and co-twins who
responded don't know to many of the items, agreement between
twin and co-twin report was variable. In our previous report, we indicated
that there was only modest agreement (contingency coefficient=0.50) between
twin and co-twin report on whether CSA had occurred
(Kendler et al,
2000). The present results indicate that as one explores the
details of the CSA experience, agreement becomes even more precarious. This
pattern of results is to be expected. Whereas a twin might confide in a
co-twin regarding the experience of abuse, and that piece of information might
be readily recalled by the co-twin, details and specifics about the experience
might either be less likely to be divulged or less likely to be recalled. None
the less, the co-twin data confirmed that attempted or completed intercourse
and the use of force or threats were associated with higher risk for lifetime
psychopathology in the abused twin.
![]() |
Clinical Implications and Limitations |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
LIMITATIONS
![]() |
ACKNOWLEDGMENTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Briere, J. & Runtz, M. (1988) Symptomatology associated with childhood sexual victimization in a nonclinical adult sample. Child Abuse and Neglect, 12, 51-59.[CrossRef][Medline]
Browne, A. & Finkelhor, D. (1986) Impact of child sexual abuse: a review of the research. Psychological Bulletin, 99, 166-177[CrossRef]
Bushnell, J. A., Wells, J. E. & Oakley-Browne, M. A. (1992) Long-term effects of intrafamilial sexual abuse in childhood. Acta Psychiatrica Scandinavica, 85, 136-142.[Medline]
Dinwiddie, S., Heath, A. C., Dunne, M. P., et al (2000) Early sexual abuse and lifetime psychopathology: a co-twincontrol study. Psychological Medicine, 30, 41-52.[CrossRef][Medline]
Fergusson, D. M. & Mullen, P. E. (1999) Childhood Sexual Abuse: An Evidence Based Perspective (Developmental clinical psychology and psychiatry series, Vol. 40). Thousand Oaks, CA: Sage.
Fergusson, D. M., Horwood, J. & Lynskey, M. (1996) Childhood sexual abuse and psychiatric disorder in young adulthood: II. Psychiatric outcomes of childhood sexual abuse. Journal of the American Academy of Child and Adolescent Psychiatry, 34, 1365-1374.
Kendler, K. S. & Prescott, C. A. (1998)
Cannabis use, abuse, and dependence in a population-based sample of female
twins. American Journal of Psychiatry,
155,
1016-1022.
Kendler, K. S. & Prescott, C. A. (1999) A
population-based twin study of lifetime major depression in men and women.
Archives of General Psychiatry,
56, 39-44.
Kendler, K. S., MacLean, C., Neale, M. C., et al (1991) The genetic epidemiology of bulimia nervosa. American Journal of Psychiatry, 148, 1627-1637.[Abstract]
Kendler, K. S., Neale, M. C., Kessler, R. C., et al (1992a) Generalized anxiety disorder in women. Archives of General Psychiatry, 49, 267-272[Abstract]
Kendler, K. S., Neale, M. C., Kessler, R. C., et al (1992b) The genetic epidemiology of phobias in women: the interrelationship of agoraphobia, social phobia, situational phobia, and simple phobia. Archives of General Psychiatry, 49, 273-281.[Abstract]
Kendler, K. S., Neale, M. C., Kessler, R. C., et al (1992c) A population-based twin study of major depression in women: the impact of varying definitions of illness. Archives of General Psychiatry, 49, 257-266.[Abstract]
Kendler, K. S., Heath, A. C., Neale, M. C., et al (1992d) A population-based twin study of alcoholism in women. Journal of the American Medical Association, 268, 1877-1882.[Abstract]
Kendler, K. S., Neale, M. C., Kessler, R. C., et al (1993) Panic disorder in women: a population based twin study. Psychological Medicine, 23, 397-406.[Medline]
Kendler, K. S., Bulik, C. M., Silberg, J., et al
(2000) Childhood sexual abuse and adult psychiatric and
substance use disorders: an epidemiological and cotwin control analysis.
Archives of General Psychiatry,
57,
953-959.
Martin, J., Anderson, J., Romans, S., et al (1993) Asking about child sexual abuse: methodological implications of a two-stage survey. Child Abuse and Neglect, 17, 383-392.[CrossRef][Medline]
Mullen, P. E., Martin, J. L., Anderson, J. C., et al (1993) Childhood sexual abuse and mental health in adult life. British Journal of Psychiatry, 163, 721-732.[Abstract]
Romans, S., Martin, J. & Mullen, P. (1994) Child sexual abuse (CSA) and later eating disorders: a New Zealand epidemiological study. Neuropsychopharmacology, 10, 92S.
Romans, S., Martin, J., Anderson, J., et al (1995) Factors that mediate between child sexual abuse and adult psychological outcome. Psychological Medicine, 25, 127-142.[Medline]
SAS Institute (1989) SAS/STAT=AE User's Guide, Version 6. Cary, NC: SAS Institute.
SAS Institute (1996) SAS/STAT=AE Software: Changes and Enhancements. Cary, NC: SAS Institute.
Spaccarelli, S. (1994) Stress, appraisal, and coping in child sexual abuse: a theoretical and empirical review. Psychological Bulletin, 116, 340-362.[CrossRef][Medline]
Spaccarelli, S. & Kim, S. (1995) Resilience criteria and factors associated with resilience in sexually abused girls. Child Abuse and Neglect, 19, 1171-1182.[CrossRef][Medline]
Spitzer, R., Williams, J., Gibbon, M., et al (1988) Structured Clinical Interview for DMSIIIR: Patient Version (SCIDP, 4/1/88). New York: Biometrics Research Department, New York State Psychiatric Institute.
Wonderlich, S., Brewerton, T., Jocic, Z., et al (1997) Relationship of childhood sexual abuse and eating disorders. Journal of the American Academy of Child and Adolescent Psychiatry, 36, 1107-1115.[Medline]
Received for publication June 22, 2000. Revision received May 8, 2001. Accepted for publication May 17, 2001.
Related articles in BJP: