Does your patient have a psychiatric illness or nonverbal learning disorder?

Neuropsychological/psychoeducational testing. Traditionally, clinicians suspected NLD if a patient had a ≥10 point difference between performance intelligence quotient (IQ) and verbal IQ on the Wechsler Intelligence Scale for Children (WISC-III).⁸ However, the most recent version—the WISC-IV⁹—incorporates changes based on new neurologic models of cognitive functioning, and performance IQ and verbal IQ are no longer calculated. Thus, interpreting this split in IQ type with regard to NLD is no longer straightforward. IQ tests, such as the Woodcock-Johnson¹⁰ battery, which assesses visual-spatial thinking and fluid reasoning, may be particularly important in characterizing NLD deficits—especially when used in conjunction with other neuropsychological batteries, which may directly assess discrete abilities related to visual and spatial processing.

A thorough social and educational history, IQ testing, neuropsychological batteries, and a psychoeducational assessment can help determine the extent of cognitive deficits that may require accommodations at school or work and characterize the complex interplay of specific deficits and functioning.

Table 1

Clinical manifestation of nonverbal learning disorder

Differential diagnosis

ADHD. Patients diagnosed with ADHD or NLD may have a history of attention difficulties and hyperactivity. These clinical similarities may include restlessness, distractibility, impulsivity, and poor attention (Table 2).^11,12 In adults, these features may attenuate and patients with NLD or ADHD could appear normoactive. Individuals with NLD demonstrate withdrawal, anxiety, and continued social skills deficits,¹³ whereas adult ADHD patients show persistent attention difficulties. Although both groups may have difficulty maintaining steady employment, NLD patients’ employment failures often are caused by cognitive and social difficulties as opposed to problems with attention.

The psychopathology of these 2 conditions differs in that ADHD is characterized primarily by prefrontal dysfunction.¹⁴ However, in a small study of children with NLD (N=20), all participants also met diagnostic criteria for ADHD; therefore, the true epidemiologic comorbidity is unknown.¹⁵

BD. Because patients with NLD may experience affective symptoms similar to those with BD, it is critical to clarify the temporal course of mood symptoms and understand the complex relationships between symptoms and external events (Table 2).^11,12 In BD, mood symptoms are cyclical, punctuated by discrete periods of euthymia. In NLD affective symptoms are clearly linked to learning difficulties and impaired information processing. Research shows cognitive deficits in individuals with BD often persist during euthymic periods.¹⁶ Literature suggests that cognitive deficits in adult BD commonly involve verbal memory, executive function, and attention, whereas patients with NLD often have strong verbal memory.^17,18

Individuals with BD may understand the intentions of others and—especially in periods of hypomania or mania—will engage others. In contrast, persons with NLD struggle to attract and engage friends, may be irritable when they misunderstand social cues, may be bullied or taken advantage of by others, and may struggle to communicate this problem to clinicians. NLD patients’ sense of frustration typically does not vary; a continuous depressed or anxious mood may improve briefly when they feel accepted in their environment. This pattern can be discerned from BD by strictly applying DSM-IV-TR criteria for variability in mood states.¹⁹ BD treatment may be complicated in patients with comorbid NLD. These patients may underreport adverse effects of medications, including metabolic effects and cognitive dulling, which results in a complicated and frustrating clinical course.²⁰

Asperger’s disorder. Patients with NLD—a neuropsychological disorder—may present with social interaction difficulties that seem similar to those of Asperger’s disorder—a behavioral disorder. Overlapping behaviors, similar cognitive processes, and coexisting conditions may challenge even experienced clinicians (Table 3).^21-23 However, impairments are more severe in Asperger’s disorder and will present as early as age 4. Patients with Asperger’s disorder show difficulty communicating characterized by unusual interactions, such as pedantic or 1-sided discussions of topics that are unusual for the patient’s age group and inattentiveness to social cues. By contrast, communication difficulties in children with NLD are not apparent until after they start school.

Both Asperger’s disorder and NLD patients will show noticeable variations in thought process that often are apparent in conversations. Individuals with Asperger’s disorder may have some concrete thinking, although they often express idiosyncratic thinking, whereas individuals with NLD often show concrete logic. An individual with NLD may be easily overwhelmed by peer group social interactions but remains emotionally aware of his or her shortcomings and may be able to handle 1-on-1 interactions. Individuals with Asperger’s disorder will demonstrate restrictive interests or repetitive behaviors, a characteristic typically not seen in individuals with NLD. Patients with Asperger’s disorder may have specific skills, such as expertise with directions and spatial reasoning, whereas individuals with NLD may get lost even when traveling to familiar places or may have difficulty relating directions. Both groups likely will have good reading skills but patients with NLD will have trouble comprehending and integrating the material, evident by difficulty with multiple choice questions or “story problems.” Individuals with either disorder may develop frustration and anger with their challenges.