The British Journal of Psychiatry (2006) 188: 288-289. doi: 10.1192/bjp.bp.105.010447
© 2006 The Royal College of Psychiatrists
Impact of psychiatric disturbance on identifying psychiatric disorder in relatives: study of mothers and daughters
HELEN F. COELHO and
PETER J. COOPER
Winnicott Research Unit, School of Psychology, University of Reading,
Reading, UK
LYNNE MURRAY
Correspondence:
Professor Peter J. Cooper, Winnicott Research Unit, School of Psychology,
University of Reading, 3 Earley Gate,Whiteknights, Reading RG6 6AL, UK. E-mail
p.j.cooper{at}rdg.ac.uk
Declaration of interest None. Funding detailed in
Acknowledgements.
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ABSTRACT
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Previous studies have suggested that collecting psychiatric data on
relatives in family studies by asking probands to provide information on them
leads to a bias in estimates of morbidity risk, because
probands’accounts are influenced by their own psychiatric histories. We
investigated this in a UK sample and found that daughters’anxiety
disorder histories did not influence their reports of anxiety disorder in
mothers, but their history of mood disorder/alcohol dependence made them more
sensitive in predicting mood disorder/alcohol dependence in mothers.
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INTRODUCTION
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Information provided on the presence of anxiety, depression and alcoholism
in relatives has been found to be influenced by the informants’ own
psychiatric status (Kendler et al,
1991; Chapman et al,
1994; Roy et al,
1994; Heun et al,
1997). This suggests that for these disorders a bias in estimates
of morbidity risk will occur if diagnoses for relatives are made solely on the
basis of information obtained from probands
(Kendler, 1991). To our
knowledge, no UK studies have investigated whether an informant’s own
psychiatric history of anxiety, depression or alcoholism influences their
account of psychiatric morbidity in relatives.
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METHOD
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Study participants consisted of 115 proband–relative pairs who were
recruited into a family aggregation study of generalised social phobia and
generalised anxiety disorder. The probands were all women recruited from the
community, with a mean age of 32.1 years (s.d.=3.77). As shown in
Table 1, 39 probands had a
lifetime history of DSM–IV mood disorder (i.e. major depessive disorder
or dysthymia)/alcohol dependence (MD/AD) with or without a lifetime history of
anxiety disorder, 45 probands had no history of MD/AD (despite having a
history of anxiety disorder), and 31 probands had no history of a DSM–IV
Axis I disorder. Of the total of 115 probands, 80 had a lifetime history of
anxiety disorder. Proband diagnoses were made using the Structured Clinical
Interview for DSM–IV Axis I Disorders (SCID–1;
First et al,
1995).
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Table 1 Accuracy of probands’ predictions of anxiety disorder and mood
disorder/alcohol (MD/AD) dependence according to probands’ own
psychiatric history
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The 115 relatives were the mothers of the probands in all but 8% of cases
(father in 1%, brother in 1% and sister in 6%). The mean age of the relatives
was 56.8 years (s.d.=8.56).
Relatives were also interviewed using the SCID–1, with interviewers
masked to the probands’ psychiatric status. Lifetime diagnoses of
anxiety disorders, depressive disorders and alcohol dependence were made in
consensus meetings between the SCID interviewer and one of the authors
(P.J.C.).
Probands were interviewed about the psychiatric histories of their
relatives. For MD and generalised anxiety disorder, established criteria were
used (Endicott et al,
1975; Kendler et al,
1997). For the other disorders detailed research criteria were
specified. Lifetime diagnoses were again made in independent consensus
meetings (with P.J.C.), and these were compared with the
‘gold-standard’ diagnosis that was obtained from the direct
interview.
The sensitivity and specificity of probands’ accounts of their
relatives’ lifetime history of any DSM–IV anxiety disorder (a
composite category because of the low numbers involved) and MD/AD were
calculated, and binary logistic regression models were fitted to assess
whether the accuracy of the probands’ information on relatives’
diagnoses was predicted by their own psychiatric histories of these disorders
(taking into account the age difference between the proband and the other
informant).
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RESULTS
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The sensitivity and specificity of the probands’ predictions of
lifetime anxiety disorder in their relatives are shown in
Table 1. There was no
difference in the proportion of false-negative or false-positive diagnoses
made by probands with and without a history of anxiety disorder
(Fisher’s exact test: P=0.21 and P=0.52 respectively).
A binary logistic regression model confirmed that the likelihood of a correct
prediction of anxiety disorder in relatives was the same for anxiety-disorder
and non-anxiety-disorder probands (odds ratio 1.01, 95% CI 0.36–2.86;
P=0.98).
Table 1 also shows the
sensitivity and specificity of the probands’ accounts of lifetime MD/AD
in their relatives, according to whether the probands themselves had a
lifetime diagnosis of MD/AD, anxiety disorder without MD/AD, or no disorder.
Probands who had never met the criteria for any DSM–IV Axis I disorder
were more likely to make a false-negative prediction of MD/AD in their
relatives than either probands who themselves had a lifetime diagnosis of
MD/AD (Fisher’s exact test: P=0.002) or probands who had a
lifetime diagnosis of any anxiety disorder without MD/AD (Fisher’s exact
test: P=0.07). The proportion of false-negative predictions of MD/AD
in their relatives made by the probands in the two psychopathology groups did
not differ significantly. Similarly, the proportion of false-positive
predictions of MD/AD in the relatives did not differ significantly between the
three proband groups. A binary logistic regression model indicated that,
compared with probands who had no lifetime DSM–IV Axis I disorder, the
probands with a history of MD/AD were more than four times as likely to
correctly predict a history of MD/AD in their relatives (odds ratio 4.03, 95%
CI 0.95–17.14; P=0.06). Although not statistically significant,
probands with a lifetime diagnosis of any anxiety disorder without MD/AD were
approximately two and a half times more likely to correctly predict a history
of MD/AD in their relatives (odds ratio 2.56, 95% CI 0.74–8.92;
P=0.14).
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DISCUSSION
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In contrast to previous studies (Kendler
et al, 1991; Chapman
et al, 1994), we did not find that probands with and
without a history of anxiety disorder differed in the accuracy of their
reporting of anxiety disorder in their relatives. One possible reason for this
discrepancy is that the commonest anxiety disorder in the present study was
social phobia, and it may be that these cases do not show the same trend
towards decreased specificity and increased sensitivity (when predicting the
same disorder in relatives) as that shown by informants with panic disorder
(Chapman et al, 1994)
and generalised anxiety disorder (Kendler
et al, 1991). Our results suggest that for family studies
of anxiety disorder in the UK, no bias in estimates of morbidity rates would
be likely to occur if diagnoses were made according to information obtained
from probands alone.
With regard to MD/AD, as has been reported previously
(Chapman et al, 1994; Roy et al, 1994;
Heun et al, 1997), we
found that probands with a history of such disorders showed higher sensitivity
in their predictions of MD/AD in their relatives than probands with no history
of a DSM–IV Axis I disorder. Furthermore, again as reported previously
(Chapman et al, 1994;
Roy et al, 1994), our
data suggest that this increased sensitivity was not specific to MD/AD in the
probands. Probands with a history of an anxiety disorder without MD/AD were
also more sensitive in their predictions of MD/AD in relatives than probands
with no history of disorder. We found no evidence that the probands in the
psychopathology groups were less specific in their predictions of MD/AD in
their relatives than probands with no history of disorder. It could be argued
that the use of the composite category of MD/AD for these analyses might have
obscured diagnostically specific links. However, although we could not perform
separate analyses for prediction of alcoholism in relatives (because of their
low rate of this disorder), when only mood disorder diagnoses for relatives
were selected, the pattern of results did not change.
It is also possible that our findings were influenced by specific aspects
of the sample that was studied. The present study principally concerned
mothers and daughters and it is possible that the findings may not generalise
to other family relationships. Women may be more aware than men of psychiatric
disorder in their relatives, although there is no evidence that psychiatric
disturbance would have a different impact on the sensitivity and specificity
of men’s predictions compared with those of women.
Finally, given that (to our knowledge) this is the first UK study to
investigate whether probands’ predictions of anxiety disorder and MD/AD
in relatives are influenced by the probands’ own psychiatric history, it
is important to consider that differences between our findings and those of
previous studies may be due to cultural factors in the UK. These might include
taboos about mental illness, societal understanding of mental illness, and the
way in which UK families communicate – in particular, the way in which
they discuss mental health issues.
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ACKNOWLEDGMENTS
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We thank Susan Campbell, Barbara Kennedy, Paula Libberton, Monika
Parkinson, Melanie Royal-Lawson and Sheila Summers for recruiting and
assessing the proband sample, and Françoise Hentges, Jo Pearson and
Hannah Seabrook for assisting in the assessment of relatives. We also thank
all the participants in this study.
This research was funded by the Medical Research Council and the Health
Foundation.
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REFERENCES
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Received for publication February 24, 2005.
Revision received May 16, 2005.
Accepted for publication May 31, 2005.
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ABSTRACT
INTRODUCTION
