Counseling Points - Psychiatric Nurse 11/08 - (Page 6)

Pathophysiology ADHD is a highly heterogeneous, nonprogressive, neurological condition. The exact pathophysiological mechanisms are not confirmed, although genetic, neurological, and environmental influences all play a role. ADHD is considered to be highly inheritable, with estimates that range from 60%-90% across generations.7,14 Twin studies confirm a genetic link between monozygotic twins.7 Because of these strong familial patterns, ADHD is thought to be a polygenic disorder that interferes with the encoding of the function of neurotransmitters and their receptors.8,15,19 Current investigations center around identifying affected genes and the resultant mechanisms responsible for the dysregulation of neurotransmitters—primarily the catecholamines dopamine and norepinephrine, their receptors, and their transporters.20 These neurotransmitters influence attention, arousal, impulsivity, and mood. Defects in the neurotransmission process result in insufficient amounts of catecholamines being available to modulate the behaviors they influence.7,20 The role of neurotransmitter dysregulation in causing ADHD is supported by the fact that effective ADHD medications work on the dopaminergic and noradrenergic systems. Other research is attempting to identify structural anomalies in the brain, with an emphasis on the neurocircuitry of the prefrontal cortex, an area that is rich in dopamine receptors. Recent studies have demonstrated anatomic differences in individuals with ADHD compared with individuals who do not have ADHD. For instance, the right prefrontal cortex, caudate nucleus, and globus pallidus often are somewhat smaller and demonstrate less blood flow and decreased electrical activity.7,14 As these are key areas of the brain that help children process stimuli, control emotions, develop social awareness, and sustain attention while inhibiting untoward behaviors, these findings support the idea that neuroanatomic differences play a role in ADHD. it is not a direct result of those conditions or influences. They may, however, exacerbate the symptomatology, and higher rates of ADHD have been noted in such populations. 14,15 In addition, there is no proof that nutritional intake of free sugars or artificial additives causes ADHD.21,22 ADHD Signs and Symptoms Signs and symptoms of ADHD are determined, in part, by the age of the child and the form of ADHD that the child has. For ADHD-H/I and ADHD-I, at least six of the nine characteristics in each of the diagnostic categories specified in Table 1 must be present.5 For ADHDC, at least six symptoms from both diagnostic categories are required.5 The individual who does not have documented symptoms of ADHD before the age of 7 years but who meets the criteria at the time of diagnosis is usually classified as ADHD—Not Otherwise Specified.5 The symptoms listed as part of the APA’s diagnostic criteria are most commonly seen in school-age children. When preschoolers are diagnosed with ADHD, it is usually because they are exhibiting symptoms of hyperactivity and impulsivity: They have difficulty sitting still for quiet activities, following simple instructions, and waiting their turn, and often demonstrate other developmentally immature behaviors. Many preschool children with ADHD have poor social skills with their peers and may become aggressive, pushing other children or grabbing toys away. Because many toddlers or preschoolers exhibit behaviors such as inattention or impulsivity, care must be taken to differentiate whether the symptomatology is merely part of the normal developmental trajectory or diagnostic of ADHD. ADHD symptoms in adolescents differ somewhat from those seen in school-age children and may include sleep problems, restlessness, and disorganization; teens may also demonstrate heightened motor activity (e.g., foot tapping).15 Other symptoms include significant academic difficulties and school failure, anxiety disorders, poor social interaction skills with possible antisocial behavior, and illicit substance and/or alcohol use.15 Many adolescents meet less than six of the necessary designated APA symptoms within a specific category, but still have significant impairment concomitant with an ADHD diagnosis.8 Risk Factors Numerous risk factors for ADHD have been identified. Symptoms of ADHD can be seen in association with neurological impairment resulting from infection (e.g., meningitis, encephalitis), injury (e.g., closed head trauma, lead intoxication), hypoxia, or maternal substance abuse during pregnancy.14,15 ADHD is also more common in children who were very low birth weight infants. 7 Although ADHD can occur with other disabling conditions (e.g., sensory impairment, intellectual disability, and serious psychosocial and emotional disturbances) or in the presence of other extrinsic influences (e.g., dysfunctional parenting or a poor socioeconomic background), COUNSELING POINTS™ 6 The Diagnostic Process To date, there are no genetic or neuroimaging tests that clearly establish the diagnosis of ADHD. In addition, there continues to be controversy regarding the overdiagnosis of ADHD in children and adolescents. When evaluating a person for ADHD, it is important to consider the pattern, severity, and pervasiveness of

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