ADHD in Schizophrenia Patients: Recommendations for Managing a Common Comorbidity
Attention deficit hyperactivity disorder (ADHD) is one of the most common psychiatric conditions.1 This disorder has been found to affect 5.9–7.1% of children and adolescents and is associated with significant functional impairment.2 Although it was believed that this condition typically resolved during adolescence, current research shows that symptoms persist into adulthood in two-thirds of patients.1 The estimated prevalence of ADHD in adults is 2.5–5%.2
Fortunately, ADHD can be effectively treated in both children and adults.1 However, because comorbidities are highly prevalent in patients with ADHD, it is important for clinicians to carefully assess patients prior to initiating therapy. Epidemiological and clinical research has found that 10–20% of patients with mental health disorders suffer from ADHD. In addition, evidence has shown that patients with ADHD, as well as their family members, have an increased risk in developing psychotic disorders. Because of this, a thorough evaluation of a patient is necessary so that proper treatment can be initiated.1,2
One of the most common, yet most understudied, comorbid conditions is schizophrenia and ADHD.1,2 Unfortunately, both of these conditions are highly debilitating for a patient. Although it can be quite challenging due to significant symptom overlap between these disorders, obtaining an accurate diagnosis of the condition is the most important step in the management of a patient. It is important for clinicians to realize that a symptom such as inattention, which is frequently observed in patients with ADHD, is also often seen in the prodromal phase of schizophrenia. Because of this, it is imperative that a thorough patient assessment is completed to ensure successful patient management.
Stimulants, such as methylphenidate and amphetamines, are the most common medications used to treat ADHD.2 While these medications have proven to be very effective in ADHD patients, use of stimulants in patients with psychotic disorders remains controversial.1,2 In general, providers are often wary of using these medications in patients who suffer from psychosis. Because stimulants are thought to work antagonistically to antipsychotics, it is believed that these medications can actually cause a worsening of a patient's psychosis. Additionally, clear guidelines on the use of stimulants in patients who concomitantly suffer from psychotic disorders have not been established, making treating these comorbid conditions challenging.2 If stimulant abuse or misuse is suspected, nonstimulant medications, such as atomoxetine or bupropion, should be used. Additionally, medication pick-up and delivery can be employed when medication diversion is a concern.
Unfortunately, there is limited and conflicting evidence regarding stimulant use in patients with psychotic disorders.2 In data obtained from several case reports, psychosis is described as an adverse event in patients taking stimulants. Additionally, older review data found that 40% of patients with schizophrenia taking a stimulant experienced worsening of psychotic symptoms.2 On the other hand, evidence obtained from several case reports and a systematic review found that stimulants did not cause a worsening of a patient's positive symptoms, and actually were found to improve a patient's negative symptoms.