3 Overlap of symptoms between anxiety and depression and comorbidity with other conditions
An important and frequently-asked question concerns whether anxiety and depression are in fact two sides of the same coin. Do anxiety and depression lie on a continuum with overlapping social, environmental, biological and psychological causes? Or, do anxiety disorders and major depressive illness represent discrete ‘categories’ of illness?
To consider these questions, we first have to examine the symptom profiles for anxiety and depressive illness (see Figure 3). Recent studies suggest that around '85% of patients with depression also experience significant symptoms of anxiety' (Möller et al., 2016). Similarly, 'symptoms of depression occur in up to 90% of patients with anxiety', and such ‘comorbid anxiety and depression’ can occur at any age.
(*) Somatic complaints: unexplained physical complaints such as headache, stomach ache, chronic pain.