In the past, it was believed that anxiety was a symptom of depression and that having either condition increased the likelihood of developing the other. However, research has shown that these conditions can coexist, a phenomenon known as comorbidity. This means that an individual can experience both anxiety and depression simultaneously. Both conditions are linked to neurobiology and stem from imbalances in brain chemistry and overactivity in the stress response system.

Having both anxiety and depression can make the condition more chronic and treatment more intensive, as it can significantly impair functioning and hinder interpersonal relationships. It can also significantly increase the risk of suicide.

Anxiety is characterized by chronic caution and worry about one's environment and constant nervousness and stress about future events, while depression is marked by feelings of hopelessness and an exclusive focus on negative aspects. Therefore, having both anxiety and depression can result in thoughts such as "The future is scary and I'm terrified of it. I know I won't be able to cope with it anyway, so giving up is obviously the only choice I have." This thought process involves an overestimation of risk and an underestimation of the individual's ability to cope, leading to avoidance of uncomfortable situations rather than developing the skills to manage them. Even simple tasks like asking for a favor or applying for a job can seem threatening, leading to negative self-perception and perpetuating the cycle.

Treatment for comorbid anxiety and depression can include therapy, such as cognitive behavioral therapy, which helps individuals think more positively and learn more adaptive responses, and medication prescribed by a psychiatrist to relax the stress response system and alleviate symptoms. On a personal level, incorporating physical exercise, meditation, and rhythmic breathing exercises into one's routine can also facilitate a more peaceful state of mind. It is important to seek help from a professional for these conditions.