Patients with developmental disabilities (DDs) are not a uniform population. Therefore, they present with varied psychiatric signs and symptoms, probably because of unique neurotransmitter dysfunction.2
Regardless of the neuroanatomic dysfunction involved, symptoms tend to cluster. The most frequent reason for psychiatric consultation is for the management of aggressive and impulsive symptoms. Stereotyped and self-injurious behaviors (SIBs) are also frequent,4 in addition to affective, psychotic, attention deficit, and anxiety disorders, all discussed below.
When the same types of disorders occur in patients who also have epilepsy, there are special considerations in regards to pharmacologic intervention. (See Approach to patients with comorbid epilepsy.)
The wide-ranging presentation of aggression and impulse control dysfunction may color intervention. Patients who display uncontrolled outbursts because of overwhelming arousal can be discriminated from patients with affective irritability often associated with ictal causes or exacerbations. Other patients may present with more goal-directed behavior and may be candidates for behavioral treatments.4
Self-injurious and stereotypic behavior is diagnosed more easily and may be particular to the underlying organic disorder (e.g., Lesch-Nyhan syndrome). Overarousal has been associated with serotonin dysfunction along with excessive dopaminergic and opioid activity.2,4
Affective disorders commonly are underdiagnosed in individuals with DDs. Prevalence rates show frequencies from three to seven times that found in the general population.5 In the mildly impaired, the diagnosis of depression can be made with the Diagnostic and Statistical Manual of Mental Disorders criteria, but a reliance on exacerbations of irritability and psychomotor agitation aid in evaluating the more severely handicapped.6
Mania also can be found. It usually is exhibited by increased motor activity, decreased sleep, and aggression.5
Diagnosing psychosis in the DD population often is difficult. A thought disorder generally is not obvious because of language impairment. Likewise, evaluating the presence of delusions, hallucinations, and illusions is difficult in the setting of general perceptual compromise, but response to hallucinations or catatonic behavior can provide some objective evidence of a psychotic process.7 “Voices” whose content is derogatory may suggest a psychotic depression, in which treatment should focus on the mood disorder as well as on the psychosis.
The many organic causes of psychosis can be evaluated based on the acronym ADMITTING:5
As detailed in another area of this website, attention-deficit hyperactivity disorders (ADHD) also can be seen in the developmentally disabled. The diagnosis of the disorder is the same as in the general population. The frequency of ADHD in individuals with MR (approximately 11%) is from two to three times greater than expected in a cognitively normal population.5 Behavioral dysfunction can accrue from the disorder in much the same way as in others with ADHD. Treatment usually includes both behavioral and pharmacologic modalities.5
Anxiety disorders are very common in patients with MR. They can appear as:
As with other psychiatric disorders, the lack of verbal abilities may make it necessary to rely on behavioral features for correct diagnosis.5
Adapted from: Barry JJ and Huynh N. Psychotropic drug use in patients with epilepsy and developmental disabilities. In: Devinsky O and Westbrook LE, eds. Epilepsy and Developmental Disabilities. Boston: Butterworth-Heinemann; 2001;205–217. With permission from Elsevier (www.elsevier.com).
Reviewed and revised June 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.
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