Psychiatric Comorbidity and Symptom Overlap
After screening and obtaining a history of the full diagnostic criteria and collateral information to support a childhood onset, you can diagnose ADHD in your patient. However, you must first rule out that the symptoms are not caused, or contributed to, by another psychiatric or physical condition.
This is a critical step in the diagnostic process, because patients with ADHD have depression, anxiety, and substance abuse at twice the rate of the general population. The Psychiatric Times article cited a study that found that 87% of adults with ADHD had one other psychiatric diagnosis, and 56% had two.
These statistics highlight the need for an accurate diagnosis, which includes ruling out co-occurring diagnoses. Therefore, a complete evaluation for ADHD should also involve the patient's psychiatric history—including screening for mood, anxiety, psychotic, and substance use disorders, which can all cause symptoms that mimic those of ADHD.
In addition, it is important to rule out medical conditions, and medications the patient is taking, that can cause symptoms similar to those of ADHD. Therefore, in most cases, I obtain laboratory values, such as a complete blood cell count, a comprehensive metabolic panel, and thyroid-stimulating hormone and lipid levels, and measure vital signs to rule out such medical conditions as hyperthyroidism, hypertension, and electrolyte abnormalities. Obtaining lab values and vital signs also verifies that the patient does not have any contraindications to medications that may be considered later.
Owing to the overlapping and in some cases synergistic symptomatology of ADHD and co-occurring psychiatric diagnoses, I would support primary care physicians who make a referral to a psychiatrist or a psychologist to formally diagnose a patient. However, in many cases, the wait for a psychiatry referral can be long, if not indefinite. Therefore, in rural and underserved settings, it is completely appropriate for a primary care physician to make the diagnosis and initiate treatment, because prolonging the patient's suffering will only serve to create more dysfunction and decreased quality of life at home and at work/school.
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Cite this: Diagnosing and Treating Adult ADHD: A Guide - Medscape - Feb 01, 2016.