Evidence-based assessment/Generalized anxiety disorder (assessment portfolio)

Click Here for Landing Page
Click Here for Landing Page
HGAPS New for Fall 2022: HGAPS and Psychology Conferences
Click Here for Landing Page
Click Here for Landing Page

HGAPS is finding new ways to make psychological science conferences more accessible!

Here are examples from APA 2022 and the JCCAP Future Directions Forum. Coming soon... ABCT!
~ More at HGAPS.org ~



Subject classification: this is a psychology resource.

Medical disclaimer: This page is for educational and informational purposes only and may not be construed as medical advice. The information is not intended to replace medical advice offered by physicians. Please refer to the full text of the Wikiversity medical disclaimer.


  • For background information on what assessment portfolios are, click the link in the heading above.

Want even 'more' information about this topic? There's an extended version of this page here.

Diagnostic criteria for generalized anxiety disorder

edit

ICD-11 Diagnostic Criteria[1]

  • Generalised anxiety disorder is characterized by marked symptoms of anxiety that persist for at least several months, for more days than not, manifested by either general apprehension (i.e. ‘free-floating anxiety’) or excessive worry focused on multiple everyday events, most often concerning family, health, finances, and school or work, together with additional symptoms such as muscular tension or motor restlessness, sympathetic autonomic over-activity, subjective experience of nervousness, difficulty maintaining concentration, irritability, or sleep disturbance. The symptoms result in significant distress or significant impairment in personal, family, social, educational, occupational, or other important areas of functioning. The symptoms are not a manifestation of another health condition and are not due to the effects of a substance or medication on the central nervous system.

Changes in DSM-5

  • The diagnostic criteria for generalized anxiety disorder changed slightly from DSM-IV-TR to DSM-5. Summaries are available here.


Base rates of GAD in different clinical settings

edit

This section describes the demographic setting of the population(s) sampled, base rates of diagnosis, country/region sampled and the diagnostic method that was used. Using this information, clinicians will be able to anchor the rate of GAD that they are likely to see in their clinical practice.

  • To see prevalence rates across multiple disorders, click here.
Demography Setting Base Rate Diagnostic Method
Adults and adolescences in all of U.S.A. US National Comorbidity Survey Replication (NCS-R; age > = 13)[2] 0.9% (age 13-17)

2.9% (age 18-64)

1.2% (age >= 65)

2.0% (age >=13)

Fully-structured Composite International Diagnostic Interview (CIDI Version 3.0)
Psychiatric outpatients Individuals seeking treatment in a Psychiatric Outpatient Clinic (age range not reported)[3] 21% Structured Clinical Interview for DSM-IV (SCID)
Caucasian youth Children seeking treatment in a Child & Adolescent Anxiety Diagnostic Clinic (age 7 – 18 years old)[4] 0.39% (parent report)

0.38% (child report)

Anxiety Disorders Interview Schedule for Children for DSM-IV

Spence Children's Anxiety Scale (SCAS)

Caucasian, African American, Asian American, and Hispanic population Collaborative Psychiatric Epidemiology Studies (CPES; age >= 18, data merged from three representative national database)[5] 4.1% (female)

2.1% (male)

World Mental Health Survey Initiative Version of the World Health Organization Composite International Interview (WMH-CIDI)
Pennsylvania Metropolitan Community Sample, all individuals with eating disorders (ages 13 – 65)[6] 10% Structured Clinical Interview for DSM-IV (SCID)
Adolescents in all of U.S.A. National Comorbidity Survey Replication Adolescent Supplement (NCS-A; ages 3–18 in the continental U.S)[7] 2.2% World Health Organization Composite International Diagnostic Interview (WHO-CIDI)
Adolescents in all of U.S.A National Comorbidity Survey Replication Adolescent Supplement (NCS-A; ages 3–18 in the continental U.S)[8] 5.4% Composite International Diagnostic Interview (CIDI)
North Carolina Rural community sample African American and White youth (ages 13-16)[9] 1.4% The Child and Adolescent Psychiatric Assessment (CAPA)
Texas Metropolitan Community Sample (ages 11-17)[10] 0.4% Diagnostic Interview Schedule for Children, Version IV (DISC-IV)
Midwestern Urban Incarcerated adolescents (ages 10-18)[11] 1% Diagnostic Interview Schedule for Children, Version IV (DISC-IV)
Non-institutionalized general US population LGBTQ sample (ages 20-65)[12] Women:

14.8% same-sex

22.5% bisexual

Men:

16.9% same-sex

11.5% bisexual

The Alcohol Use Disorder and Associated Disabilities Interview Schedule-IV (AUDADIS-IV)
Non-institutionalized general US population Cross-ethnic American population (ages 18+)[13] White 8.6%

African Americans 4.9%

Hispanic Americans 5.8%

Asian Americans 2.4%

World Mental Health Survey Initiative Version of the World Health Organization Composite International Interview (WMH-CIDI)
Outpatient clinics worldwide Samples across multiple studies worldwide (all ages)[14] 5% Clinical evaluations
Outpatient clinic worldwide Samples across multiple studies worldwide (all ages)[14] 10% Standardized Diagnostic Interviews (SDIs)
People during pregnancy and postpartum Samples across multiple studies worldwide[15] 2.4% Standardized Diagnostic Interviews (SDIs)
Older adults Samples across in Switzerland, German, Italy, England, Spain, and Israel 3.7% (age 65-69)

3.7% (age 70-74)

2.6% (age 75-79)

2.0% (age >80)

Clinical evaluations

Search terms: [General Anxiety Disorder] AND [prevalence OR incidence] in GoogleScholar and PsycINFO

Psychometric properties of screening instruments for GAD

edit

The following section contains a list of screening and diagnostic instruments for generalized anxiety disorder. The section includes administration information, psychometric data, and PDFs or links to the screenings.

  • Screenings are used as part of the prediction phase of assessment; for more information on interpretation of this data, or how screenings fit in to the assessment process, click here.
  • For a list of more broadly reaching screening instruments, click here.
Screening measures for GAD
Measure Format (Reporter) Age Range Administration/

Completion Time

Where to Access
Penn State Worry Questionnaire (PSWQ)[16] Questionnaire (Adult Version, Child Version) 18+ (Adult Version), 6-18 (Child Version) 4 minutes PSWQ homepage

PSWQ Adult Version

PSWQ Child Version

PSWC-C Korean

PSWQ-C Danish

Scoring the PSWQ-C

Assessment Center Online Adult Version

Screen for Child Anxiety Related Emotional Disorder (SCARED)[16] Questionnaire (Child, Parent) 8-19 9 or 16 minutes SCARED homepage

SCARED English + Translations & Automatic Scoring

Assessment Center Online Youth Version

Assessment Center Online Parent Version

Child Behavior Checklist (CBCL)[16] Questionnaire (Parent report) 6-18 10 minutes ASEBA homepagePurchase
Generalized Anxiety Disorder Screener (GAD-7)[16] Questionnaire (Self-report) 18+ 5 minutes GAD-7 homepage

GAD-7 PDF

Assessment Center Online Version

Note: Reliability and validity are included in the extended version. This table includes measures with Good or Excellent ratings.

Likelihood ratios and AUCs of screening instruments for GAD

edit
  • For a list of the likelihood ratios for more broadly reaching screening instruments, click here.
Screening Measure (Primary Reference) Area Under Curve (AUC) LR+ (Score) LR- (Score) Clinical Generalizability Where to Access
Penn State Worry Questionnaire (PSWQ)[17] 0.74

(N=164)

1.8 (65+) 0.5 (< 65) Generalized Anxiety Disorder vs. social anxiety disorder, adults presenting to specialty anxiety clinic PSWQ Adult Version

PSWQ Child Version

Assessment Center Online Adult Version

Screen for Child Anxiety Related Disorders (SCARED)[18] .70

(N=243)

5.0 (+32) .04 High: Pure anxiety disorder versus non-anxiety psychiatric disorder, excluding children with disruptive disorder and depression SCARED English + Translations & Automatic Scoring

Assessment Center Online Youth Version

Assessment Center Online Parent Version

CBCL Anxious/Depressed Scale T-score[19] .75 (N=1445) 1.49 (9+) .67(9-) Inpatient and outpatient children and adolescents Purchase

Note: “LR+” refers to the change in likelihood ratio associated with a positive test score, and “LR-” is the likelihood ratio for a low score. Likelihood ratios of 1 indicate that the test result did not change impressions at all. LRs larger than 10 or smaller than .10 are frequently clinically decisive; 5 or .20 are helpful, and between 2.0 and .5 are small enough that they rarely result in clinically meaningful changes of formulation[20].

Search terms: [General Anxiety Disorder] AND [children OR adolescents OR pediatric] AND [sensitivity OR specificity] in GoogleScholar and PsycINFO

Interpreting depression screening measure scores

edit
  • For information on interpreting screening measure scores, click here.

Gold standard diagnostic interviews

edit
  • For a list of broad reaching diagnostic interviews sortable by disorder with PDFs (if applicable), click here.
edit
Diagnostic instruments for GAD
Measure Format (Reporter) Age Range Administration/

Completion Time

Where to Access
Anxiety Disorders Interview Schedule for Children/Parent[21] Structured Interview

(Child (ADIS-C), Parent (ADIS-P))

6-16[22] Varies Purchase
Anxiety and Related Disorders Interview Schedule for DSM-5 (ADIS-5)[16] Structured Interview (Adult) 16+ Varies Purchase
Structured Clinical Interview for DSM-5-Clinician Version (SCID-5-CV)[23] Structured Interview (Adult ) 16+ Varies Website and purchase

Note: Reliability and validity are included in the extended version. This table includes measures with Good or Excellent ratings.

The following section contains a list of process and outcome measures for generalized anxiety disorder. The section includes benchmarks based on published norms for several outcome and severity measures, as well as information about commonly used process measures. Process and outcome measures are used as part of the process phase of assessment. For more information of differences between process and outcome measures, see the page on the process phase of assessment.

Process measures

edit

Outcome and severity measures

edit
  • This table includes clinically significant benchmarks for anxiety specific outcome measures
  • Information on how to interpret this table can be found here.
  • Additionally, these vignettes might be helpful resources for understanding appropriate adaptation of outcome measures in practice.
  • For clinically significant change benchmarks for the CBCL, YSR, and TRF total, externalizing, internalizing, and attention benchmarks, see here.
Clinically significant change benchmarks with common instruments for GAD
Measure Cut-off scores Critical Change
(unstandardized scores)
Benchmarks Based on Published Norms
A B C 95% 90% SEdifference
GAD-7 -1 1.3 0.5 0.6 0.5 0.3
PSWQ 51 73 59 9 8 4.8
SCARED 9.9 18.1 15.3 8.9 7.5 4.5

Note: “A” = Away from the clinical range, “B” = Back into the nonclinical range, “C” = Closer to the nonclinical than clinical mean.

Search terms: [General Anxiety Disorder] AND [children OR adolescents OR pediatric] AND [clinical significance OR outcomes] in GoogleScholar and PsycINFO

Treatment

edit
Treatment Information

Individuals suffering from GAD tend to be high users of outpatient medical care. When treating GAD, physicians should first determine whether pharmacotherapy, psychotherapy, or a combination of the two treatments would be most beneficial to the patient. Literature suggests that treatment of GAD frequently consists of a combination of psychotherapy and pharmacotherapy. Although these therapies have the potential to be effective individually, previous work demonstrates that when combined the degree of clinically significant change increases significantly. Recent studies (e.g., Gorman, 2003[24]; Walkup et al., 2008[25]) have provided evidence to support this claim with the most efficacious medication and behavioral interventions listed below.

  1. Medication Interventions
    1. Sertraline (Zoloft) has been shown to reduce experiences and effects of GAD above and beyond that of placebo conditions.
    2. Pregabalin. The mean baseline-to-endpoint decreases in total Hamilton anxiety scale score in the patients given 150 mg/day of pregabalin (–9.2) was significantly greater than the decrease in those given placebo (–6.8)[26].
    3. Paroxetine. Remission was achieved by 30% of patients in the 20-mg paroxetine groups compared with 20% given placebo. For all three domains of the Sheehan Disability Scale, significantly greater improvement was seen with paroxetine than placebo[27].
  2. Behavioral interventions
    1. Cognitive behavioral therapy. Fourteen 60-minute sessions, which include CBT in anxiety-management skills, followed by behavioral exposure to anxiety-provoking situations have been shown to be effective in treating GAD. A review of studies by Fisher and Durham (1999)[28] revealed significant recovery rates at a 6 month follow up after CBT.
    2. Exposure therapy and modeling therapy. One meta-analysis found that virtual reality exposure therapy for anxiety disorders had a large effect size (Cohen's d=1.11) compared to controls.[29]
    3. Mindfulness meditation. New treatment options such as mindfulness meditation-based stress reduction interventions have also shown to reduce symptoms over the long-term.[30]
  3. Combination treatment
    1. Previous research suggests that combination therapy that includes components of psychotherapy and pharmacotherapy are the most efficacious in treating GAD. In a study comparing the efficacies GAD treatments, Walkup and colleagues demonstrated a 21-25% improvement of combination therapy over cognitive behavioral therapy or sertraline alone during short-term treatment. These findings suggest that among effective treatments, combination therapy has the potential to provide the best chance for a positive outcome. See Gorman, 2003[24]; Walkup et al., 2008[25].

External Resources

edit
  1. ICD-10 diagnostic criteria
  2. Find-a-Therapist
    • This is a curated list of find-a-therapist websites where you can find a provider
  3. NIMH entry about anxiety disorders
  4. OMIM (Online Mendelian Inheritance in Man)
  5. eMedicine entry about anxiety disorders
  6. Society of Clinical Child and Adolescent Psychology
  7. Effective Child Therapy information on Fear, Worry, & Anxiety
    • Effective Child Therapy is website sponsored by Division 53 of the American Psychological Association (APA), or The Society of Clinical Child and Adolescent Psychology (SCCAP), in collaboration with the Association for Behavioral and Cognitive Therapies (ABCT). Use for information on symptoms and available treatments.
  8. Links to SCARED Child, Parent, and Adult + Translations

References

edit
Click here for references
  1. https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/1712535455
  2. Kessler, RC; Petukhova, M; Sampson, NA; Zaslavsky, AM; Wittchen H, -U (September 2012). "Twelve-month and lifetime prevalence and lifetime morbid risk of anxiety and mood disorders in the United States.". International journal of methods in psychiatric research 21 (3): 169-84. PMID 22865617. 
  3. Zimmerman, M; Rothschild, L; Chelminski, I (October 2005). "The prevalence of DSM-IV personality disorders in psychiatric outpatients.". The American journal of psychiatry 162 (10): 1911-8. PMID 16199838. 
  4. Brown-Jacobsen, AM; Wallace, DP; Whiteside, SP (September 2011). "Multimethod, multi-informant agreement, and positive predictive value in the identification of child anxiety disorders using the SCAS and ADIS-C.". Assessment 18 (3): 382-92. PMID 20644080. 
  5. McLean, Carmen P.; Asnaani, Anu; Litz, Brett T.; Hofmann, Stefan G. (2011-08-01). "Gender differences in anxiety disorders: Prevalence, course of illness, comorbidity and burden of illness". Journal of Psychiatric Research 45 (8): 1027–1035. doi:10.1016/j.jpsychires.2011.03.006. ISSN 0022-3956. PMID 21439576. PMC PMC3135672. https://www.sciencedirect.com/science/article/pii/S0022395611000458. 
  6. Kaye, WH; Bulik, CM; Thornton, L; Barbarich, N; Masters, K (December 2004). "Comorbidity of anxiety disorders with anorexia and bulimia nervosa.". The American journal of psychiatry 161 (12): 2215-21. PMID 15569892. 
  7. Merikangas, KR; He, JP; Burstein, M; Swanson, SA; Avenevoli, S; Cui, L; Benjet, C; Georgiades, K et al. (October 2010). "Lifetime prevalence of mental disorders in U.S. adolescents: results from the National Comorbidity Survey Replication--Adolescent Supplement (NCS-A).". Journal of the American Academy of Child and Adolescent Psychiatry 49 (10): 980-9. PMID 20855043. 
  8. Kessler, R. C., Avenevoli, S., Costello, E. J., Georgiades, K., Green, J. G., Gruber, M. J., . . . Merikangas, K. R. (2012). Prevalence, persistence, and sociodemographic correlates of DSM-IV disorders in the National Comorbidity Survey Replication Adolescent Supplement. Archives of General Psychiatry, 69(4), 372-380. doi:10.1001/archgenpsychiatry.2011.160
  9. Angold, Adrian; Erkanli, Alaattin; Farmer, Elizabeth M. Z.; Fairbank, John A.; Burns, Barbara J.; Keeler, Gordon; Costello, E. Jane (October 2002). "Psychiatric disorder, impairment, and service use in rural African American and white youth". Archives of General Psychiatry 59 (10): 893–901. ISSN 0003-990X. PMID 12365876. https://www.ncbi.nlm.nih.gov/pubmed/12365876. 
  10. Roberts, RE; Roberts, CR; Xing, Y (December 2007). "Rates of DSM-IV psychiatric disorders among adolescents in a large metropolitan area.". Journal of psychiatric research 41 (11): 959-67. PMID 17107689. 
  11. ABRAM, KAREN M.; CHOE, JEANNE Y.; WASHBURN, JASON J.; TEPLIN, LINDA A.; KING, DEVON C.; DULCAN, MINA K.. "Suicidal Ideation and Behaviors Among Youths in Juvenile Detention". Journal of the American Academy of Child & Adolescent Psychiatry 47 (3): 291–300. doi:10.1097/chi.0b013e318160b3ce. http://linkinghub.elsevier.com/retrieve/pii/S0890856709623121. 
  12. Bostwick, Wendy B.; Boyd, Carol J.; Hughes, Tonda L.; McCabe, Sean Esteban (2010-3). "Dimensions of Sexual Orientation and the Prevalence of Mood and Anxiety Disorders in the United States". American Journal of Public Health 100 (3): 468–475. doi:10.2105/AJPH.2008.152942. ISSN 0090-0036. PMID 19696380. PMC PMC2820045. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2820045/. 
  13. Asnaani, Anu; Richey, J. Anthony; Dimaite, Ruta; Hinton, Devon E.; Hofmann, Stefan G. (2010-8). "A Cross-Ethnic Comparison of Lifetime Prevalence Rates of Anxiety Disorders". The Journal of nervous and mental disease 198 (8): 551–555. doi:10.1097/NMD.0b013e3181ea169f. ISSN 0022-3018. PMID 20699719. PMC PMC2931265. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2931265/. 
  14. 14.0 14.1 Rettew, David C.; Lynch, Alicia Doyle; Achenbach, Thomas M.; Dumenci, Levent; Ivanova, Masha Y. (2009-09). "Meta-analyses of agreement between diagnoses made from clinical evaluations and standardized diagnostic interviews". International Journal of Methods in Psychiatric Research 18 (3): 169–184. doi:10.1002/mpr.289. ISSN 1049-8931. http://dx.doi.org/10.1002/mpr.289. 
  15. Fawcett, Emily J.; Fairbrother, Nichole; Cox, Megan L.; White, Ian R.; Fawcett, Jonathan M. (2019-07-23). "The Prevalence of Anxiety Disorders During Pregnancy and the Postpartum Period: A Multivariate Bayesian Meta-Analysis". The Journal of Clinical Psychiatry 80 (4). doi:10.4088/JCP.18r12527. ISSN 1555-2101. PMID 31347796. PMC PMC6839961. https://www.psychiatrist.com/JCP/article/Pages/2019/v80/18r12527.aspx. 
  16. 16.0 16.1 16.2 16.3 16.4 Hunsley, John; Mash, Eric J. (2008). A guide to assessments that work. New York: Oxford University Press. ISBN 9780195310641. OCLC 314222270. https://www.worldcat.org/oclc/314222270. 
  17. Fresco, David M.; Mennin, Douglas S.; Heimberg, Richard G.; Turk, Cynthia L.. "Using the Penn State Worry Questionnaire to identify individuals with generalized anxiety disorder: a receiver operating characteristic analysis". Journal of Behavior Therapy and Experimental Psychiatry 34 (3-4): 283–291. doi:10.1016/j.jbtep.2003.09.001. http://linkinghub.elsevier.com/retrieve/pii/S0005791603000569. 
  18. Birmaher, B; Khetarpal, S; Brent, D; Cully, M; Balach, L; Kaufman, J; Neer, SM (April 1997). "The Screen for Child Anxiety Related Emotional Disorders (SCARED): scale construction and psychometric characteristics.". Journal of the American Academy of Child and Adolescent Psychiatry 36 (4): 545-53. PMID 9100430. 
  19. Eimecke, Sylvia D.; Remschmidt, Helmut; Mattejat, Fritz (2011-03). "Utility of the Child Behavior Checklist in screening depressive disorders within clinical samples". Journal of Affective Disorders 129 (1-3): 191–197. doi:10.1016/j.jad.2010.08.011. https://linkinghub.elsevier.com/retrieve/pii/S0165032710005458. 
  20. Sackett, D. L., Straus, S. E., Richardson, W. S., Rosenberg, W., & Haynes, R. B. (2000). Evidence-based medicine: How to practice and teach EBM. Edinburgh: Churchill Livingstone.
  21. "Test-Retest Reliability of Anxiety Symptoms and Diagnoses With the Anxiety Disorders Interview Schedule for DSM-IV: Child and Parent Versions". Journal of the American Academy of Child & Adolescent Psychiatry 40 (8): 937–944. 2001-08-01. doi:10.1097/00004583-200108000-00016. ISSN 0890-8567. https://www.sciencedirect.com/science/article/pii/S0890856709603427. 
  22. LYNEHAM, HEIDI J.; ABBOTT, MAREE J.; RAPEE, RONALD M. (2007-06). "Interrater Reliability of the Anxiety Disorders Interview Schedule for DSM-IV: Child and Parent Version". Journal of the American Academy of Child & Adolescent Psychiatry 46 (6): 731–736. doi:10.1097/chi.0b013e3180465a09. ISSN 0890-8567. https://doi.org/10.1097/chi.0b013e3180465a09. 
  23. Shabani, Amir; Masoumian, Samira; Zamirinejad, Somayeh; Hejri, Maryam; Pirmorad, Tahereh; Yaghmaeezadeh, Hooman (2021-05). "Psychometric properties of Structured Clinical Interview for DSM‐5 Disorders‐Clinician Version (SCID‐5‐CV)". Brain and Behavior 11 (5). doi:10.1002/brb3.1894. ISSN 2162-3279. PMID 33729681. PMC PMC8119811. https://onlinelibrary.wiley.com/doi/10.1002/brb3.1894. 
  24. 24.0 24.1 Gorman, JM (2003). "Treating generalized anxiety disorder.". The Journal of clinical psychiatry 64 Suppl 2: 24-9. PMID 12625796. 
  25. 25.0 25.1 Walkup, JT; Albano, AM; Piacentini, J; Birmaher, B; Compton, SN; Sherrill, JT; Ginsburg, GS; Rynn, MA et al. (25 December 2008). "Cognitive behavioral therapy, sertraline, or a combination in childhood anxiety.". The New England journal of medicine 359 (26): 2753-66. PMID 18974308. 
  26. Pande, AC; Crockatt, JG; Feltner, DE; Janney, CA; Smith, WT; Weisler, R; Londborg, PD; Bielski, RJ et al. (March 2003). "Pregabalin in generalized anxiety disorder: a placebo-controlled trial.". The American journal of psychiatry 160 (3): 533-40. PMID 12611835. 
  27. Rickels, K; Zaninelli, R; McCafferty, J; Bellew, K; Iyengar, M; Sheehan, D (April 2003). "Paroxetine treatment of generalized anxiety disorder: a double-blind, placebo-controlled study.". The American journal of psychiatry 160 (4): 749-56. PMID 12668365. 
  28. Fisher, PL; Durham, RC (November 1999). "Recovery rates in generalized anxiety disorder following psychological therapy: an analysis of clinically significant change in the STAI-T across outcome studies since 1990.". Psychological medicine 29 (6): 1425-34. PMID 10616949. 
  29. Powers, Mark B.; Emmelkamp, Paul M.G.. "Virtual reality exposure therapy for anxiety disorders: A meta-analysis". Journal of Anxiety Disorders 22 (3): 561–569. doi:10.1016/j.janxdis.2007.04.006. https://doi.org/10.1016/j.janxdis.2007.04.006. 
  30. Miller, J. J.; Fletcher, K.; Kabat-Zinn, J. (May 1995). "Three-year follow-up and clinical implications of a mindfulness meditation-based stress reduction intervention in the treatment of anxiety disorders". General Hospital Psychiatry 17 (3): 192–200. ISSN 0163-8343. PMID 7649463. https://www.ncbi.nlm.nih.gov/pubmed/7649463. 

Cite error: <ref> tag with name "CostelloEtAl1996" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "ChorpitaEtAl2000" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "ChorpitaEtAl2005" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "HaleEtAl2014" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "LynehamEtAl2007" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "MarchEtAl1997" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "McLeanEtAl2011" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "SeligmanEtAl2004" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "WhitakerEtAl1990" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "SpitzerEtAl2006" defined in <references> is not used in prior text.
Cite error: <ref> tag with name "vanGastelEtAl2008" defined in <references> is not used in prior text.

Cite error: <ref> tag with name "WoodEtAl2002" defined in <references> is not used in prior text.