Effects of Expectation, Medication and Placebo on Objective and Self-rated Performance During the Quantified Behavior Test in Patients With Untreated ADHD and Substance Use Disorder

Introduction: During the last decade, neuropsychiatric impairments in adults have more often been observed. Requests for neuropsychiatric investigations, especially concerning Attention Deficit Hyperactivity Disorder (ADHD) has increased. The core ADHD symptoms in adults include a frequent and persistent pattern of inattention/distractibility and/or hyperactivity/impulsivity (Adler 2004; Adler & Chua 2002; McGough & Barkley 2004). In a Swedish study, 22 % of the outpatients in general psychiatric care, were diagnosed with ADHD (Nylander et al 2009).

Individuals with ADHD also have an increased risk for other psychiatric disorders, e.g. major depressive episodes, bipolar disorder, anxiety disorders and antisocial personality disorder (Rasmussen & Levander 2009; Torgersen, Gjervan & Rasmussen 2006). The co-occurrence of ADHD and substance use disorder (SUD) is a prevalent phenomenon that has been demonstrated in numerous studies over the past decade (Arias et al 2008; Bernardi et al 2012; van Emmerik-van Oortmerssen et al 2012).

The prevalence of substance abuse in adults with ADHD has been estimated at 50 % and among addicts seeking treatment, one third of the patients are identified as probable ADHD, when screening instruments have been used (Sullivan & Rodnik-Levin 2001; Ohlmeier et al 2008). The National Board of Health and Welfare in Sweden noted that the presence of people with ADHD and substance abuse varies between 20 % and 35 % depending on what kind of drugs that have been used (Socialstyrelsen 2002).

Pharmacotherapy, mainly with central stimulant medication, is considered to be the treatment of choice for ADHD. In addition, there are patients who request an ADHD diagnosis to obtain drug treatment (Harrison, Edwards & Parker 2007).

Patients' expectation can influence the outcome of a treatment (Bingel et al 2011). Linde et al showed that patients with high expectations before the acupuncture treatment, achieved better treating result than the patients who had lower expectations of treatment (Linde, Fässler & Meissner 2011). A person's expectation is an important part of the so-called placebo effect . The placebo effect is well known and clinically important phenomenon in the patient's treatment. Extensive research has been conducted to elucidate this (Meissner et al 2011; Collocca et al 2013; Enck et al 2013).