Differential diagnosis, comorbidity, and treatment of attention-deficit/hyperactivity disorder in relation to bipolar disorder or borderline personality disorder in adults

Background: Attention-deficit/hyperactivity disorder (ADHD) in adults can resemble, and often co-occurs with, bipolar disorder (BD) and borderline personality disorder (BPD). This can lead to mistaken diagnoses and ineffective treatment, resulting in potentially serious adverse consequences. All three conditions can substantially impair well-being and functioning, while BD and BPD are associated with suicidality. Objectives: To update clinicians on the overlap and differences in the symptomatology of ADHD versus BD and BPD in adults; differential diagnosis of ADHD from BD and BPD in adults; and diagnosis and treatment of adults with comorbid ADHD-BD or ADHD-BPD. Methods: We searched four databases, referred to the new Diagnostic and Statistical Manual of Mental Disorders, 5th edition, used other relevant literature, and referred to our own clinical experience. Results: ADHD coexists in 20% of adults with BD or BPD. BD is episodic, with periods of normal mood although not necessarily function. In patients with comorbid ADHD-BD, ADHD symptoms are apparent between BD episodes. BPD and ADHD are associated with chronic trait-like symptoms and impairments. Overlapping symptoms of BPD and ADHD include impulsivity and emotional dysregulation. Symptoms of BPD but not ADHD include frantically avoiding real/imagined abandonment, suicidal behavior, self-harm, chronic feelings of emptiness, and stress-related paranoia/severe dissociation. Consensus expert opinion recommends that BD episodes should be treated first in patients with comorbid ADHD, and these patients may need treatment in stages (e.g. mood stabilizer[s], then a stimulant/atomoxetine). Data is scarce and mixed about whether stimulants or atomoxetine exacerbate mania in comorbid ADHD-BD. BPD is primarily treated with psychotherapy. Principles of dialectical behavioral treatment for BPD may successfully treat ADHD in adults, as an adjunct to medication. No fully evidence-based pharmacotherapy exists for core BPD symptoms, although some medications may be effective for individual symptom domains, e.g. impulsivity (shared by ADHD and BPD). In our experience, treatment of ADHD should be considered when treating comorbid personality disorders. Conclusions: It is important to accurately diagnose ADHD, BD, and BPD to ensure correct targeting of treatments and improvements in patient outcomes. However, there is a shortage of data about treatment of adults with ADHD and comorbid BD or BPD.