Assessing and Treating Clients With ADHD

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Attention deficit hyperactivity disorder and its treatment

Attention deficit hyperactivity disorder (ADHD) is increasingly being seen not just as a disorder of attention, nor just as a disorder of children. Paradigm shifts are altering the landscape for treatment options across the full range of ADHD symptoms, from inattention to impulsivity. This chapter will provide an overview of the psychopharmacology of ADHD, including only short discussions of the symptoms of ADHD. The mechanism of action of stimulants and nonstimulants in ADHD will also be explored. Information on the full clinical descriptions and formal criteria for how to diagnose and rate ADHD and its symptoms should be obtained by consulting standard reference sources. The discussion here will emphasize the links between various brain circuits and their neurotransmitters and the various symptoms and comorbidities of ADHD, and how these are linked to effective psychopharmacologic treatments. The goal of this chapter is to acquaint the reader with ideas about the clinical and biological aspects of attention, impulsivity, and hyperactivity, also covering some of the aspects involved in treating adults with this disorder. For details of doses, side effects, drug interactions, and other issues relevant to the prescribing of drugs for ADHD in clinical practice, the reader should consult standard drug handbooks (such as Stahl’s Essential Psychopharmacology: the

).Prescriber’s Guide

Symptoms and circuits: ADHD as a disorder of the prefrontal cortex

ADHD is noted for a trio of symptoms: inattention, hyperactivity, and impulsivity ( ). It isFigure 12-1 currently hypothesized that all these symptoms arise in part from abnormalities in various circuits involving the prefrontal cortex ( through ). Specifically, the most prominentFigures 12-2 12-8 symptoms of inattention in ADHD, better known as executive dysfunction and as the inability to sustain attention and thus to solve problems, are hypothetically linked to inefficient information processing in the dorsolateral prefrontal cortex (DLPFC) ( , , ). DLPFC isFigures 12-2 12-3 12-7 activated by a cognitive task known as the -back test, which can be monitored in living patientsn doing it while in a functional magnetic resonance imaging (fMRI) brain scanner (explained in Figure

). Problems activating this part of the brain cut across many psychiatric disorders that share the12-3 symptom of executive dysfunction, not just ADHD but also including schizophrenia (discussed in

), major depression (discussed in ), mania (discussed in ), anxietyChapter 4 Chapter 6 Chapter 6 (discussed in

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Figure 12-1. . There are three major categories of symptoms associated with attentionSymptoms of ADHD deficit hyperactivity disorder (ADHD): inattention, hyperactivity, and impulsivity. Inattention itself can be divided into difficulty with selective attention and difficulty with sustained attention and problem solving.

Figure 12-2. . Problems with selective attention are believed to beMatching ADHD symptoms to circuits linked to inefficient information processing in the dorsal anterior cingulate cortex (dACC), while problems with sustained attention are linked to inefficient information processing in the dorsolateral prefrontal cortex (DLPFC). Hyperactivity may be modulated by the prefrontal motor cortex and impulsivity by the orbitofrontal cortex (OFC).

Figure 12-3. . Sustained attention is hypotheticallySustained attention and problem solving: the -back testn modulated by a cortico-striato-thalamo-cortical (CSTC) loop that involves the dorsolateral prefrontal cortex (DLPFC) projecting to the striatal complex. Inefficient activation of the DLPFC can lead to difficulty following through or finishing tasks, disorganization, and trouble sustaining mental effort. Tasks such as the -back testn are used to measure sustained attention and problem-solving abilities. In the 0-back variant of the -back test, an participant looks at a number on the screen, and presses a button to indicate which number it is. In the 1-back variant, a participant only looks at the first number, and when the second number appears the participant is supposed to press a button corresponding to the first number. Higher values are correlated with increasedn difficulty in the test.

Figure 12-4. . Selective attention is hypothetically modulated by aSelective attention: the Stroop task cortico-striato-thalamo-cortical (CSTC) loop arising from the dorsal anterior cingulate cortex (dACC) and projecting to the striatal complex, then the thalamus, and back to the dACC. Inefficient activation of dACC can result in symptoms such as paying little attention to detail, making careless mistakes, not listening, losing things, being distracted, and forgetting things. An example of a test that involves selective attention, and thus should activate the dACC, is the Stroop task. The Stroop task requires the participants to name the color with which a word is written, instead of saying the word itself. In the present case, for example, the word "blue" is written in orange. The correct answer is therefore "orange," while "blue" is the incorrect choice.

Figure 12-5. . Impulsivity is associated with a cortico-striato-thalamo-cortical (CSTC) loop thatImpulsivity involves the orbitofrontal cortex (OFC), the striatal complex, and the thalamus. Examples of impulsive symptoms in ADHD include talking excessively, blurting things out, not waiting one’s turn, and interrupting.

), pain (discussed in ), and disorders of sleep and wakefulness (discussed in Chapter 9 Chapter 10 ). One can see how inefficient information processing in this particular DLPFC circuitChapter 11

when put under a cognitive "load" can be associated with the same symptom in many different psychiatric disorders. This is why diagnosis in psychiatry is now moving from describing categorical syndromes that mix together many symptoms (as in the DSM and ICD), towards characterizing single symptom domains such as executive dysfunction that cut across many psychiatric disorders, sometimes called Research Domain Criteria (RDoC) for future diagnostic schemes that are set up to better correlate with neuroimaging and genetic findings.

Another symptom of ADHD is inattention, or not being able to focus, and thus differing fromselective the executive dysfunction described above. The symptom of difficulty focusing is hypothetically linked to inefficient information processing in a different brain area, namely the dorsal anterior cingulate cortex (dACC) ( , , ). The dACC can be activated by tests of selective attention,Figures 12-2 12-4 12-7 such as the Stroop test (explained in ). ADHD patients may either fail to activate theFigure 12-4 dACC when they should be focusing their attention, or they activate this part of the brain very inefficiently and only with great effort and easy fatigability.

Other areas of prefrontal cortex that are hypothetically not functioning efficiently in ADHD are the orbitofrontal cortex (OFC), linked to symptoms of impulsivity ( , , ) and theFigures 12-2 12-5 12-7 supplementary motor area, linked to symptoms of motor hyperactivity ( , , ). TheFigures 12-2 12-6 12-7 OFC is hypothetically linked to a wide variety of symptoms

Figure 12-6. . Motor activity, such as hyperactivity and psychomotor agitation or retardation, canHyperactivity be modulated by a cortico-striato-thalamo-cortical (CSTC) loop from the prefrontal motor cortex to the putamen (lateral striatum) to the thalamus and back to the prefrontal motor cortex. Common symptoms of hyperactivity in children with ADHD include fidgeting, leaving one’s seat, running/climbing, being constantly on the go, and having trouble playing quietly.

that cut across several psychiatric conditions, including impulsivity in ADHD ( , , Figures 12-2 12-5 12-7 ), impulsivity and violence in schizophrenia (discussed in ), suicidality in depressionChapter 4 (discussed in ), impulsivity in mania (discussed in ), and impulsivity/compulsivityChapter 6 Chapter 6 in substance abuse (discussed in ). Impulsive symptoms in other psychiatric conditionsChapter 14 commonly comorbid with ADHD are also hypothetically related to the orbitofrontal cortex, such as conduct disorder, oppositional defiant disorder, and bipolar disorder ( ). Impulsivity is Figure 12-8 discussed extensively in (see through 14-8 and through 14-5).Chapter 14 Tables 14-1 Figures 14-1