We are now going to discuss the epidemiology of generalized anxiety disorder (GAD)
which includes an analysis of the data concerning the population and prevalence. There is some
discrepancy in the available information which might have to do with the changing
categorization of anxiety disorders in the DSM (Robichaud et al., 2019) and the differences
between DSM categorizations of generalized anxiety disorder compared to the International
Classification of Diseases (ICD) in international epidemiological studies of GAD (Bandelow &
Michaelis, 2015).
Another contributing factor to discrepancies in statistics concerning GAD might be the
high degree of comorbidity of GAD and other psychiatric and physical disorders (Pelletier et al.,
2017; Black & Grant, 2014). Over 90% of individuals who meet the criteria for GAD in a given
year will also have at least one other diagnosis (Robichaud et al., 2019).
There is also some variability in the agreed upon demographic variables related to GAD
(Robichaud et al., 2019). The demographic variables most consistently reported include being
female (OR [unadjusted odds ratio] 1.6; 95% CI, 1.3 to 2.1), single (OR 1.9; 95% CI, 1.4 to 2.6),
unemployed (OR 1.9%; 95% CI, 1.5 to 2.5), and middle-aged (age 35-54 years) (OR 1.6; 95%
CI, 1.0 to 2.7) (Watterson et al., 2017). Those not as commonly reported in the epidemiological
research include low socioeconomic status (Allen et al., 2014), poor access to health care and
racial discrimination (Yang et al., 2023; Burke et al., 2023; Kogan et al., 2022; Owais et al.,
2023).
Epidemiological studies assess different kinds of prevalence rates, including lifetime
prevalence and 12-month prevalence (Bandelow & Michaelis, 2015). Lifetime prevalence is the
proportion of individuals who have been diagnosed with GAD once in their life whereas 12month prevalence is the proportion who were diagnosed within a year of the survey (Bandelow
& Michaelis, 2015). The lifetime prevalence of GAD in Canada is 8.7% (95% CI, 8.2%-9.3%),
with 12-month prevalence of 2.6% (95% CI, 2.3% to 2.8%) (Watterson et al., 2017). These
statistics are slightly higher than international estimates with similar demographic variables
(Watterson et al., 2017).
Statistics Canada (2023) published a study claiming that the proportion of Canadians with
GAD doubled from 2012 to 2022, from 2.6% to 5.2%. These facts are not yet corroborated by
additional studies. Some large-scale epidemiological studies were conducted using DSM-III and
DSM-111R criteria, which are quite different from the criteria found in DSM-IV and DSM-V and
could contribute to differing prevalence rates (Robichaud et al., 2019). Clinical populations
reveal a higher prevalence of GAD than community based epidemiological studies (Robichaud et
al., 2019).
There is a wide range of the population diagnosed with GAD across many intersections.
The median age of onset is 31 years (Bandelow & Michaelis, 2015). The age of onset has a
bimodal distribution meaning there are two age groups with a greater risk of developing GAD,
ages 11 to early 20s and middle age (ages 35-55) with middle age having the highest proportion.
(Robichaud et al., 2019).
TIME: 4.18 (pretty fast, in voice memos)
References
Allen, J., Balfour, R., Bell, R., & Marmot, M. (2014). Social determinants of mental health.
International Review of Psychiatry, 26(4), 392-407.
https://doi.org/10.3109/09540261.2014.928270
Bandelow, B. & Michaelis, S. (2015). Epidemiology of anxiety disorders in the 21st century.
Dialogues in Clinical Neuroscience, 17(3), 327-335.
https://doi.org/10.31887/DCNS.2015.17.3/bbandelow
Black, D.W. & Grant, J.E. (2014). DSM-5® guidebook: The essential companion to the
Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. American
Psychiatric Association Publishing.
Burke, L.A., Chijioke, S., & Le, T.P. (2023). Gendered racial microaggressions and emerging
adult Black women’s social and general anxiety: Distress intolerance and stress as
mediators. Journal of Clinical Psychology, 79(4), 1051-1069.
https://doi.org/10.1002/jclp.23460
Kogan, C.S., Noorishad, P.G., Ndengeyingoma, A., Guerrier, M., & Cenat, J.M. (2022).
Prevalence and correlates of anxiety symptoms among Black people in Canada: A
significant role for everyday racial discrimination and racial microaggressions. Journal of
Affective Disorders, 308, 545-553. https://doi.org/10.1016/j.jad.2022.04.110
Owais, S., Savoy, C.D., Hill, T., Lai, J., Burack, J.A., & van Lieshout, R.J. (2023).
Mental health challenges among first nation adolescents living off-reserve
in
Ontario, Canada. Child Psychiatry & Human Development, 54(5), 12421249.
https://doi.org/10.1007/s10578-022-01333-8
Robichaud, M., Koerner, N., & Dugas, M.J. (2019). Cognitive Behavioral Treatment for
Generalized Anxiety Disorder: From Science to Practice. Routledge.
Statistics Canada. (2023). Study: Mental disorders and access to mental health care.
https://www150.statcan.gc.ca/n1/daily-quotidien/230922/dq230922b-eng.htm#
Tan, G.X.D., Xun, C.S., Hartanto, A., Goh, A.Y.H., & Mageed, N.M. (2023). Prevalence of
anxiety in college and university students: An umbrella review. Journal of Affective Disorders
Reports, 14. https://www.sciencedirect.com/science/article/pii/S2666915323001968
Watterson, R.A., Williams, J.V.A., Lavorato, D.H., & Patten, S.B. (2017). Descriptive
epidemiology of generalized anxiety disorder in Canada. The Canadian Journal of
Psychiatry, 62(1), 24-29. https://doi.org/10.1177/07067437.I6645304
Yang, P., Hernandez, B.S., & Plastino, K.A. (2023). Social determinants of mental health and
adolescent anxiety and depression: Findings from the 2018 to 2019 National Survey of
Children’s Health. International Journal of Social Psychiatry, 69(3), 795-798.
https://doi.org/10.1177/00207640221119035