Anxiety and depression are two separate conditions. The exact relationship between the two is still under study.
Even though it’s very common to find them together, any direct relationship to each other has yet to be found. For the time being, the relationship between
anxiety and depression is often referred to as comorbidity.
Meaning unrelated but co-existing. Their symptoms can overlap each other, which can make the initial diagnosis of either condition difficult. The symptoms
can also be completely independent of each other.
A study by the National Comorbidity Survey reported that 58% of patients suffering major depression also exhibited lifetime anxiety. Agitated depression and akathitic depression are most often referred to when supporting these results.
Both of these depressed states exhibit anxiety with heightened restlessness, suicidal thoughts or tendencies and a general sense of dread. While agitated depression includes symptoms of nonclinical and nonspecific panic, akathitic depression doesn’t.
Even mild anxiety symptoms are being found to have an impact on the course depression takes in individuals.
A study at the University of Pittsburg showed patients diagnosed with depression and also suffering lifetime panic symptoms experienced significant delays in the success of their treatments.
These patients also exhibited additional problems when facing the resumption of their normal activities.
There are theories regarding the possibility that depression acts similar to anxiety in attempting to encourage avoidance of potentially harmful situations. Anxiety tries to avoid and prepare for physical danger, while depression tries to avoid emotional or psychological danger.