Comorbidity in post-traumatic stress disorder: A population-based study from the two largest cities in Brazil

This study investigated the patterns of comorbidity between PTSD and depression, other anxiety disorders, alcohol-related disorders using the DSM-IV and ICD-10 criteria. The temporal sequence of the comorbid diagnoses was also investigated.

We used data from a large population-based survey carried out between 2007 and 2008 in the two largest cities in Brazil: São Paulo and Rio de Janeiro.

Diagnoses of depression, other anxiety disorders, and alcohol-related disorder were more prevalent in the people with PTSD than in those without PTSD. Using the DSM-IV criteria, approximately 67% of cases presenting PTSD were also diagnosed with another mental disorder. The diagnosis category of other anxiety disorders presented the highest proportion of comorbidity (53%). Depression was found in 34% person with PTSD whilst alcohol-related disorders were observed in 7%. Considering the temporal relationship, the onset of comorbid depression was uniformly distributed through the periods before, within the same year and after PTSD's onset. When other anxiety disorders were comorbid with PTSD, in almost 90% of the cases the other anxiety disorders preceded PTSD. For comorbidity between of alcohol-related disorders and PTSD, in 50% of the cases alcohol-related disorders preceded the diagnosis of PTSD.

The cross-sectional design imposes limitations on establishing a temporal relationship between the onset of psychiatric disorders due to memory bias.

Our findings indicate that among individuals presenting comorbid PTSD and other anxiety disorders, this diagnosis tend to precede PTSD. Comorbid cases are more frequent and more severe, and this should be taken into account in therapeutic research and clinical practice.