Diagnosis
Diagnosing of ADHD for the first time in adulthood is complex. A childhood diagnosis or childhood symptoms compatible with an ADHD diagnosis are required for an adult diagnosis. However, such a history may not be present in very bright individuals, and/or people who had primarily inattentive subtypes of ADHD, because in these individuals impairment may only become significant when structure and supports decrease and demands increase.
According to the Diagnostic and Statistical Manual of Mental Disorders (DSM) Text Revision (DSM–IV TR) (American Psychological Association 2000) diagnostic criterion, the symptoms must have started prior to age 7, be age inappropriate, cause impairment in multiple domains and not be caused by other conditions. The DSM-IV TR ADHD diagnosis is broken down into three subgroups: ADHD predominately inattentive; ADHD predominately hyperactive-impulsive; and ADHD combined type. In order for an adult to receive a diagnosis, the adult must have 6 of the 9 listed DSM-IV symptoms in at least one subtype and these symptoms must have caused consistent clinically significant impairment for 6 months or more (American Psychiatric Association 2000).
There are four important limitations in using the DSM-IV to diagnose adults with ADHD. The first is that criteria were determined in field trials of children, and as is typical the criterions were set at the 93rd percentile suggesting the top 7% would receive the diagnosis. However when the same cut offs are used in adults with ADHD the cut offs fall around the 99th percentile. Therefore, the cut offs may not be appropriate for this population and in fact some physicians advocate that 5 of the 9 symptoms are a sufficient number of symptoms for adult patients (Barkley 1990). The second limitation is that the listed hyperactive symptoms are not developmentally appropriate for adults. The third limitation is that childhood symptoms are sometimes difficult for adult patients to recall and there may not be a parent or older sibling who can validate the syndrome starting prior to age 7. When diagnosing adult ADHD, it may be appropriate to change the required age onset to 12. The fourth problem with the DSM-IV TR is measuring clinically significant impairment is difficult for both children and adults, but more so for adults who have complex and different life demands.
Scales, measures, and semi-structured clinical interviews can be efficient means of garnering information to help establish an adult ADHD diagnosis. Scales should not be used exclusively to establish a diagnosis because many psychiatric disorders have features of ADHD. Additionally, most adults experience some of the symptoms of ADHD, such as forgetfulness or disorganization, from time to time, but these symptoms are not consistent with an ADHD diagnosis in most individuals. A trained clinician with the intricate understanding of clinical impairments and the nature of ADHD can use scales and interviews to guide diagnosis.