OBJECTIVE: To examine the 1-month prevalence of generalized anxiety disorder 
(GAD) according to Diagnostic and Statistical Manual of Mental Disorders, Fourth 
Edition (DSM-IV), Diagnostic and Statistical Manual of Mental, Fifth Edition 
(DSM-V), and International Classification of Diseases, Tenth Revision (ICD-10), 
and the overlap between these criteria, in a population sample of 75-year-olds. 
We also aimed to examine comorbidity between GAD and other psychiatric 
diagnoses, such as depression.
METHOD: During 2005-2006, a comprehensive semistructured psychiatric interview 
was conducted by trained nurses in a representative population sample of 
75-year-olds without dementia in Gothenburg, Sweden (N = 777; 299 men and 478 
women). All psychiatric diagnoses were made according to DSM-IV. GAD was also 
diagnosed according to ICD-10 and DSM-V.
RESULTS: The 1-month prevalence of GAD was 4.1% (N = 32) according to DSM-IV, 
4.5% (N = 35) according to DSM-V, and 3.7% (N = 29) according to ICD-10. Only 
46.9% of those with DSM-IV GAD fulfilled ICD-10 criteria, and only 51.7% and 
44.8% of those with ICD-10 GAD fulfilled DSM-IV/V criteria. Instead, 84.4% and 
74.3% of those with DSM-IV/V GAD and 89.7% of those with ICD-10 GAD had 
depression. Also other psychiatric diagnoses were common in those with ICD-10 
and DSM-IV GAD. Only a small minority with GAD, irrespective of criteria, had no 
other comorbid psychiatric disorder. ICD-10 GAD was related to an increased 
mortality rate.
CONCLUSIONS: While GAD was common in 75-year-olds, DSM-IV/V and ICD-10 captured 
different individuals. Current definitions of GAD may comprise two different 
expressions of the disease. There was greater congruence between GAD in either 
classification system and depression than between DSM-IV/V GAD and ICD-10 GAD, 
emphasizing the close link between these entities.