When I see patients, almost 75% of the time they have comorbid illnesses which means more than one. Depression often occurs comorbidly with anxiety. We often see ADHD and anxiety in adults or ADHD and comorbid anxiety. Many people who have ADHD also have depression and/or anxiety. Some believe that the depression or anxiety is secondary to the ADHD. This is very important because we often have to discern which of the illnesses is the primary illness that is driving the co-morbid illness; to implement an effective treatment program. Often a patient might complain of symptoms of anxiety, so the practitioner will treat them for anxiety and the ADHD which is the primary illness will be taken as “confusion” caused by the anxiety. What ends up happening is the ADHD is never treated and it is the root cause of the anxiety; therefore, the patient never gets relief from the anxiety. If an anti-anxiety medication is prescribed, much of the time, this will not help the ADHD. This is why the initial evaluation is so crucial in the treatment planning and implementation.
This often works in reverse as well. Often the patient may be suffering from bipolar disorder and the practitioner will treat them for the depression anxiety comorbidity. Instead of giving the patient a mood stabilizer, the practitioner prescribes an SSRI to pick them up (which often send them into mania) and then an anti-anxiety medication to bring them down. Once again, the initial evaluation is of utmost importance in getting the appropriate diagnosis, which then leads us to the correct treatment course.
Establishing the primary illness instead of the secondary illness - if the practitioner focuses on the secondary illness such as depression which might be caused by the primary illness ADHD; then the ADHD will persist and continue cause the depressive episodes. There are several ways that a trained psychiatrist uses to determine the differences between the primary and secondary illnesses. This aspect of medicine is as much an art as it is science and comes with years of experience and study.