ADHD, mood and anxiety
Quite some people with ADHD also suffer from mood and anxiety disorders. This can place an extra burden on the person and his or her environment. It is therefore important to detect and treat comorbid disorders at an early stage. The difficulty, however, is that symptoms of ADHD can be quite similar to those of mood and anxiety disorders, such as inattentiveness, restlessness or problems with organising everyday life. Furthermore, emotional instability and sleep problems frequently occur in both ADHD, depression and anxiety. It is still unknown whether the biological mechanisms behind ADHD with comorbid depression or anxiety are different from the mechanisms that underlie the individual disorders. Furthermore, although mood and anxiety disorders are more prevalent in women than in men, more research is needed to establish whether comorbidity patterns are different between the sexes.
Mood and anxiety disorders
Mood disorders include major depression, dysthymia and bipolar disorder. As the name suggests, these disorders are characterised by a disturbed mood, i.e. the emotions a person experiences. Mood fluctuations are human, and everyone knows experiences of depression or euphoria. However, if a person experiences severe depression for a prolonged period of time (i.e. more than 2 weeks), this can have serious consequences for his/her work, private life and health. This is called major depression, which is characterised by an unpleasant mood during most of the day, intense mental anguish, the inability to experience pleasure and general loss of interest in the world. In some individuals, episodes of depression are alternated by episodes of mania (or euphoria). This is called bipolar disorder. Anxiety disorders include general anxiety disorder, phobias, panic disorder, post-traumatic stress disorder and obsessive-compulsive disorder. People with anxiety disorder suffer from prolonged fear and anxiousness, in a way that interferes with their daily lives.
Potential mechanisms of mood and anxiety
Depression and anxiety often co-occur, and are thought to have similar genetic underpinnings. However, as with many psychiatric disorders, the biological causes for mood and anxiety disorders are still poorly understood. Roughly two-thirds of patients with depression respond well to treatment with monoamines. This is a group of messenger molecules in the brain (also called neurotransmitters) including dopamine, serotonin and noradrenaline. These molecules also play a role in ADHD. For a long time it was thought that a shortage of these monoamines causes depression. However, research has shown that reality is more complex, with likely roles for other brain molecules and even the inflammatory system. Additionally, both mood and anxiety disorders are thought to be associated with a malfunctioning stress-response pathway in the brain. It has been suggested that stressful life events may trigger depression or anxiety in individuals that have a high risk for developing these disorders, based on their genetic make-up.
In summary, the biological mechanisms that underlie ADHD, mood and anxiety disorders are still poorly understood, but likely to be linked. For the development of accurate treatment it is therefore important to study the comorbid occurrence of these disorders.
It is still unknown whether the biological mechanisms behind ADHD with comorbid depression or anxiety are different from the mechanisms that underlie the individual disorders