 |
 |
|
|
|
 The LSCDQ is a province-wide longitudinal study of children that began when they were aged 5 months. It examines risk and protective factors for the development of child psychopathology and maladaptive social functioning. Well-recognized risk factors include parental psychiatric disorders, such as major depression. MDD is a common psychiatric illness in the general population and is associated with general functional impairment (1) and a reduced capacity to achieve and maintain close interpersonal relationships (2). According to a study of 850 twin families with children aged between 8 and 17 years, parental depression is associated with childhood depression and anxiety disorders (3). A large community study showed that 20% of mothers at 36 months postdelivery reported depression symptoms and that they were more likely to report behaviour problems in their infants, compared with mothers without depression symptoms (4). A recent metaanalysis by Connell and Goodman that included 134 studies conducted between 1976 and 2001 suggests that psychopathology such as depression in parents is associated with emotional and behavioural problems in their offspring (5). To determine how parental depression influences child development and psychopathology, valid measures of parental depression (including MDD) are needed. Because depression is familial with a genetic component (6–8), it is important to assess not only current parental depression but also a parent’s lifetime history of major depression. In this paper, we report on the construct validity of a brief instrument that was used to assess lifetime history of MDD in the parent sample from the LSCDQ. Several brief self-report scales exist that assess depressed mood and associated symptoms, usually those occurring in the previous 1 to 2 weeks. Although the scales are easily used in large community surveys, many are limited as measures of MDD, for the following reasons. First, resulting high scores are not specific to MDD (9,10). Second, most of these scales are designed to assess current symptoms. This means that longitudinal studies that assess the subjects on a yearly (or less frequent) basis will likely overlook episodes of depressive symptoms that occurred between follow-up assessments. Various instruments have been used to diagnose major depression in large population-based studies; these include the DIS (11), the Composite International Diagnostic Interview (12), and the Revised Clinical Interview Schedule (13). These instruments are limited when used to assess parents in community studies of child psychopathology. First, they require extensive interviewer training, adding significantly to the study cost. Second, parents in studies of children are usually the main informants for the children; adding a structured diagnostic interview of the parent(s) in addition to the questions regarding the child imposes a considerable additional burden. Third, some parents may be unwilling to participate in a study that focuses on their own psychopathology. To assess parental MDD in the LSCDQ, we developed a brief questionnaire specifically for this study, based on the DSM-IV criteria for an MDE. Assessing the validity of this instrument is problematic. The original study was designed for a large number of subjects, and because of the obvious cost limitations, it used only lay interviewers. In this study, we carried out an alternative assessment by assessing the instrument’s construct validity. We used the following questions to test the construct validity of the LSCDQ depression questionnaire: 1) Does the lifetime prevalence show the expected marked sex difference, with women showing a higher rate than men? 2) Is the rank order of the different symptoms of depression consistent with those from other studies? 3) Is there evidence for clustering of symptoms? 4) Do ever-depressed parents with 4 or more symptoms for at least 2 weeks also meet DSM-IV Criterion C (clinically significant distress or impairment), and are increased numbers of symptoms associated with increased treatment seeking or functional impairment? MethodsSubjects The LSCDQ is a prospective longitudinal study that looks at the risk and protective factors for child psychopathology and maladaptive functioning. The children make up a representative sample of the population of infants born in the province of Quebec. The institutional review board of the Institut de la statistique du Québec and the University of Montreal approved this study for research involving human subjects. After the parents received a complete description of the study, written informed consent was obtained from them. (Further details are available in English at www.stat.gouv.qc.ca/publications/liste_an.htm.) The target population of the LSCDQ was all singleton infants between 59 and 60 weeks’ gestational age in 1998 with mothers living in Quebec. Excluded were infants born in the far north administrative region, in Cree or Inuit regions, or on First Nations reserves, as well as infants at less than 24 weeks’ or greater than 42 weeks’ gestational age or for whom the duration of gestation could not be determined from the birth record. The target population represents 96.6% of the total population of Quebec infants between 59 and 60 weeks’ gestational age. Funding and SupportThis study was made possible by grants from the Quebec Ministry of Health and Social Services, the Social Sciences and Humanities Research Council of Canada, the National Health Research Development Program of Canada, the Quebec fund for research training and support to research, the Quebec health research fund, and the Quebec council for social research. The registry of live births maintained by the Quebec government was used to select infants according to the above-mentioned criteria and a stratified, 3-stage sampling design. A total of 2940 infants were selected. The choice of this number was based on a pilot study with an expected participation rate of 72% and a sampling design effect of 1.3. A total of 2223 families (75.6%) participated in the study. The lowest participation rates occurred among mothers aged 19 years and under (65.5%), mothers with only a grade school education (43.3%), mothers who did not speak either English or French at home (45.9%), and mothers living in the largest urban regions of Quebec (Montreal, 63.2%; Laval, 63.4%). The parents were predominantly French-speaking (75.2%) and Canadian-born (80.6%). Many infants (41.7%) were only children, and 9.2% of the families were single-parent (almost always mother-only) households. Few mothers (3.3%) were under age 20 years, 19.8% were aged 20 to 24 years, and 32.6% (the largest group) were aged 30 to 34 years. Similar percentages of mothers and fathers did not have a high school degree (18% and 17.6%, respectively), and similar percentages did hold a university degree (24.6% and 24.7%, respectively). One-third of the households (32.8%) reported an income of less than $30 000, 39.6% reported between $30 000 and $59 999, and 27.6% reported $60 000 or more. About one-tenth of the households (11.5%) reported welfare as the principal source of income. Of the 2223 families, 2120 were selected for the longitudinal study; these are the families examined in the present study. Procedure The LSCDQ child subjects have been assessed yearly since age 5 months. The MDD instrument was administered to parents at the third assessment, in 2000, when the infants were aged 29 months. At that time, 1997 families participated in the study (94% of the original sample). Parents and infants were assessed at home in French or English; a computerized interview was administered to the person most knowledgeable about the infant—almost always the mother—with the occasional participation of the father for relevant sections (such as questions on paternal health or education). In addition, both parents completed other self-report questionnaires, and the interviewer made direct observations of the infant, home, and neighbourhood. A broad range of social, demographic, health, and behavioural data was obtained. Instruments The LSCDQ Parental Depression Questionnaire. The parental depression questions (questionnaires available from the author) were derived in part from the National Institute of Mental Health DIS, but they do not follow the same structure as the DIS (11). Parents were first asked whether they had ever been depressed for most of the time for 2 weeks or more, because this is 1 of 2 necessary conditions for Criterion A in a DSM-IV diagnosis of MDD (loss of interest was not asked about because of the ambiguity of deciding whether a parent had suffered an MDE in the absence of depressed mood). If the parents responded “yes,” they were asked to check off which of 8 symptoms of depression they experienced during their worst (or only) spell of depression. These 8 symptoms are similar to the other DSM-IV Criterion A symptoms of MDD, with 2 exceptions. First, the DSM symptom “psychomotor agitation or retardation nearly every day” is not included, as it was not clear whether this could be reported accurately; second, 2 questions about suicide (“Did you want to die or think about suicide?” and “Did you attempt suicide?”) were not included. To obtain data similar to the DSM-IV Criterion C for major depression, parents were then asked whether they had ever sought professional help for depression or whether depression had interfered with work, school, taking care of children, or relationships with others. Parents were also asked whether they had had an episode of depressed mood lasting 2 weeks or more since the birth of their child. Finally, parents were asked for their total number of episodes of depressed mood lasting 2 weeks or more and for their age at the first and last episodes. For the mothers, an interviewer asked the depression questions and entered the responses on a computer. This interview assesses maternal, child, and some paternal characteristics, including sociodemographic, health, and behavioural data. The interview was administered to the “person most knowledgeable about the child,” which was almost always the biological mother. The paternal depression questions were part of a larger self-report questionnaire. Although some depression questionnaires were completed by nonbiological parent figures, we used only those from biological parents in the analysis. Statistical Analysis Using SPSS version 12.0 (14), we analyzed the data on parental depression obtained from biological parents who reported ever having depression for 2 weeks or more. DSM-IV Criterion A depression symptoms were added for each parent and ranged from 0 to 7. We counted a positive report of either or both items relating to suicide (passive suicidal thoughts or suicide attempt) as only one depression symptom. The numbers of mothers and fathers with missing depression data were small (0 and 7, respectively), and we did not include them in the data analysis. We used Student’s t test and Pearson’s chi-square to compare differences in the variables. ResultsAltogether, 1977 biological mothers and 1585 biological fathers completed the depression questionnaire. A total of 533 biological mothers (27.0%) reported a history of ever having dpression for 2 weeks or more, while 278 biological fathers (17.5%) reported a similar history. Table 1 lists the frequency of the individual DSM-IV depression symptoms experienced by these ever-depressed biological mothers and fathers during their worst (or only) spell of depression. The most common depression symptoms for both groups were tiredness, fatigue, or no energy; insomnia or hypersomnia; trouble concentrating; and loss of interest. Attempted suicide and wanting to die or suicidal ideation were the least common symptoms reported by both groups.
Table 2 presents the total number of depression symptoms experienced by the ever-depressed biological parents during their worst (or only) spell of depression. Most of these parents had experienced 3 or more DSM-IV Criterion A depression symptoms.
Among ever-depressed mothers, those with a greater number of DSM-IV depression symptoms were more likely to have consulted with a professional and to report that suffering from depression had interfered with their functioning, compared with those with fewer DSM-IV depression symptoms (Table 3). We also found similar results for ever-depressed fathers (Table 4).
Further, ever-depressed mothers with 4 or more depression symptoms were significantly more likely to have consulted a professional (Pearson c2 = 33.475, df 2; P < 0.001) and to have had impaired functioning (Pearson c2 = 62.805, df 2; P < 0.001), compared with those with 3 or fewer symptoms. The same relations appeared for ever-depressed fathers with 4 or more depression symptoms: they were significantly more likely to have consulted a professional (Pearson c2 = 19.801, df 2; P < 0.001) and to have had impaired functioning (Pearson c2 = 29.178, df 2; P < 0.001), compared with those with 3 or fewer symptoms. Among the total sample, we determined that more mothers than fathers had a lifetime history of ever having an MDE (363/1977, or 18.4%, compared with 173/1585, or 10.9%) and that more mothers reported having an episode of 2 weeks or more of depressed mood since the birth of the index child (229/1977, or 11.6%, compared with 75/1585, or 4.7%). DiscussionValidity of the Instrument for Assessing Lifetime Prevalence of Parental Major Depression Our results support the construct validity of our measure of lifetime major depression. Sex Differences. Our finding that the prevalence of lifetime major depression in mothers (18.4%) was greater than that in fathers (10.9%) is consistent with the literature (15). The Epidemiologic Catchment Area Study also found that the lifetime prevalence of a depressive episode in women was about twice that found in men (8.7% vs 3.6%) (16). Similarly, we found that the prevalence of major depression since the birth of the index child was over twice as high in mothers (11.4%), compared with fathers (4.7%). Ranking of Symptom Prevalence. Among the ever-depressed mothers and fathers in this study, tiredness, fatigue, or no energy; insomnia or hypersomnia; and trouble concentrating were the most frequently reported symptoms. In a review article by Weissman and others, which examined by site the “symptoms occurring in 60% or more persons with major depression,” insomnia and loss of energy were reported in 8 of 8 study sites, thoughts of death or suicide in 7 sites, and concentration problems in 6 sites (15). Hence, the frequency of reported depression symptoms in our study is generally comparable to that found in other community studies, with the obvious discrepancy being the reported rates of death or suicide thoughts. One possible explanation for the low frequency of reported death or suicide thoughts in the LSCDQ study may be related to the subject matter (namely, suicide), which is generally stigmatized. It might have been more difficult to elicit a positive response with only the 2 relevant questions from the LSCDQ instrument, compared with the other 8 studies that used the 4 questions about suicide contained in the DIS. In addition, the parents of young children (from the LSCDQ) might have been reluctant to acknowledge their death or suicide-related thoughts or behaviours within the context of a study focused primarily on their infants. Clustering of Symptoms. Most of the ever-depressed mothers (83.5%) and fathers (78.2%) in our study had also experienced 4 or more depression symptoms. This suggests a clustering of the symptom of persistent depressed mood with the other required DSM-IV criteria for MDD. Treatment Seeking and Functional Impairment. Compared with those having fewer DSM-IV Criterion A depression symptoms, ever-depressed parents with more symptoms were significantly more likely to have talked to a professional and to report that suffering from depression had interfered with their functioning. This decreased functioning and increased help-seeking behaviour suggests that the symptoms experienced by the parents were severe and probably crossed the threshold into the clinical sphere. The above-mentioned 4 points support the construct validity of our instrument for assessing lifetime parental major depression and suggest that the reported symptoms probably represent a syndrome that is close to the DSM-IV definition of an MDD. Further, our finding that fewer ever-depressed fathers than mothers had talked to a professional is consistent with the literature, which shows that female sex is associated with treatment-seeking behaviour for depression (17). Our results are particularly interesting because fathers suffering from depression reported lower rates of talking to professionals, even though they reported higher rates of functional impairment than did the mothers. In addition, since the infants were aged 29 months at the time of the LSCDQ parental depression assessment, it is unlikely that the maternal depression symptoms were secondary to the effects of the pregnancy with the identified infant. Limitations This instrument’s first limitation is that it did not assess any exclusion criteria, such as bereavement, a general medical condition, or mixed episode. This could have produced an overestimated prevalence for parental MDD. Loss of interest and psychomotor agitation or retardation were not assessed as DSM-IV Criterion A symptoms, and this could have resulted in missed cases of depression and possibly an underestimate of depression prevalence. Having mothers interviewed while fathers completed a self-administered questionnaire may have confounded sex differences. Indeed, some studies suggest that, for some diagnoses (in particular, personality disorders), the reporting perspective (that is, self-report or interview report) can influence the reporting of symptoms (18). Since women are known to suffer from other disorders (such as anxiety disorders) more than men, it is possible that the higher prevalence of depression symptoms found among mothers in this study could represent a disorder other than MDD. Similarly, our finding that mothers sought medical attention more often than fathers could be associated with another disorder or illness, since women generally tend to seek medical attention more frequently than do men. Finally, an important limitation of this study is that it reports on construct validity, and the evidence provided to diagnose MDD is indirect. Future studies using the LSCDQ parental depression questionnaire would help to determine its comparability with clinicians’ diagnoses and its test–retest reliability, sensitivity, and specificity. Nevertheless, even the commonly accepted psychometric measures have some limitations. Some authors suggest that there is no gold standard for diagnoses and that assessing subjects through another interview, even a clinician interview, can be problematic because such assessments also measure interrater agreement (19). Further, some test–retest studies with the same instrument have shown marked attenuation, such that interview subjects systematically report fewer symptoms or diagnoses on the second interview (20). Implications Our results demonstrated acceptable construct validity for this brief and simple instrument for measuring lifetime major depression in parents. The instrument may be of use in other community-based parental surveys. Our findings on parental MDD will be used in future analyses to better understand the risk factors associated with childhood psychopathology and maladaptive functioning. AcknowledgementsFor the data collection, we thank the Institut de la statistique du Québec team coordinated by Mireille Jetté. References1. Luty SE, Joyce PR, Mulder RT, McKenzie JM. Social adjustment in depression: the impact of depression severity, personality, and clinic versus community sampling. J Affect Disord 2002;70:143–54. 2. Beardslee WR, Hickey Schultz L, Selman RL. Level of social-cognitive development, adaptive functioning, and DSM-III diagnoses in adolescent offspring of parents with affective disorders: implications of the development of the capacity for mutuality. Developmental Psychopathology 1987;23:807–15. 3. Foley DL, Pickles A, Simonoff E, Maes HH, Silberg JL, Hewitt JK, and others. Parental concordance and comorbidity for psychiatric disorder and associate risks for current psychiatric symptoms and disorders in a community sample of juvenile twins. J Child Psychol Psychiatry 2001;42:381–94. 4. Civic D, Holt VL. Maternal depressive symptoms and child behavior problems in a nationally representative normal birthweight sample. Matern Child Health J 2000;4:215–21. 5. Connell AM, Goodman SH. The association between psychopathology in fathers versus mothers and children’s internalizing and externalizing behavior problems: a meta-analysis. Psychol Bull 2002;128:746–73. 6. Reinherz HZ, Paradis AD, Giaconia RM, Stashwick CK, Fitzmaurice G. Childhood and adolescent predictors of major depression in the transition to adulthood. Am J Psychiatry 2003;160:2141–7. 7. Williamson DE, Birmaher B, Axelson DA, Ryan ND, Dahl RE. First episode of depression in children at low and high familial risk for depression. J Am Acad Child Adolesc Psychiatry 2004;43:291–7. 8. Morley KI, Hall WD, Carter L. Genetic screening for susceptibility to depression: can we and should we? Aust N Z J Psychiatry 2004;38(1–2):73–80. 9. Myers JK, Weissman MM. Use of a self-report symptom scale to detect depression in a community sample. Am J Psychiatry 1980;137:1081–4. 10. Cox JL, Holden JM, Sagovsky R. Detection of postnatal depression. Development of the 10-item Edinburgh Postnatal Depression Scale. Br J Psychiatry 1987;150:782–6. 11. Robins LN, Heizer JE, Croughan JL, Ratcliff KS. National Institute of Mental Health Diagnostic Interview Schedule. Its history, characteristics, and validity. Arch Gen Psychiatry 1981;38:381–9. 12. Blazer DG, Kessler RC, McGonagle KA, Swartz MS. The prevalence and distribution of major depression in a national community sample: the National Comorbidity Survey. Am J Psychiatry 1994;151:979–86. 13. Brugha T, Nienhuis F, Bagchi D, Smith J, Meltzer H. The survey form of SCAN: the feasibility of using experienced lay survey interviewers to administer a semi-structured systematic clinical assessment of psychotic and non-psychotic disorders. Psychol Med 1999;29:703–11. 14. SPSS Inc. SPSS Version 12.0 Chicago (IL): SPSS Inc; 2003. 15. Weissman MM, Bland RC, Canino GJ, Faravelli C, Greenwald S, Hwu HG, and others. Cross-national epidemiology of major depression and bipolar disorder. JAMA 1996;276:293–9. 16. Robins LN, Regier DA. Psychiatric disorders in America: the Epidemiologic Catchment Area Study. New York: The Free Press; 1991. p 61–9. 17. Bristow K, Patten S. Treatment-seeking rates and associated mediating factors among individuals with depression. Can J Psychiatry 2002;47:660–5. 18. Edell WS, Joy SP, Yehuda R. Discordance between self-report and observer-rated psychopathology in borderline patients. J Personal Disord 1990;4:381–90. 19. Angold A, Fisher P. Interviewer-based interviews. In: Shaffer D, Lucas CP, Richters J, editors. Diagnostic assessment in child and adolescent psychopathology. New York: The Guilford Press; 1999. p 34–64. 20. Angold A, Costello EJ. The child and adolescent psychiatric assessment (CAPA). J Am Acad Child Adolesc Psychiatry 2000;39(1):39–48. Author(s)Manuscript received September 2004, revised, and accepted February 2005. 1. Assistant Professor, Department of Psychiatry, McGill University, Montreal, Quebec. 2. Associate Professor, Department of Psychiatry, McGill University, Montreal, Quebec. 3. Postdoctoral Fellow, McGill University Health Centre Research Institute, Montreal, Quebec. 4. Professor, Canada Research Chair in Child Social Development, École de psychologie, Université Laval, Quebec City, Quebec. 5. Professor, Departments of Psychiatry and Anthropology, University of Montreal, Montreal, Quebec. 6. Professor, Canada Research Chair in Child Social Development, University of Montreal, Quebec. Address for correspondence: Dr Carmella Roy, 3755 chemin de la Côte Ste-Catherine, Montreal, QC H3T 1E2 e-mail: carmella.roy@mcgill.ca
1 | 2
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||