Symptom Profiles, Psychiatric Comorbidities, and Impairments in NonVerbal Learning Disability

Abstract

Objective: Previous research strongly suggests that NonVerbal Learning Disability (NVLD) is a disorder of visuospatial deficits. However, it remains unclear whether it is a discrete neurodevelopmental disorder, or, a set of visuospatial deficits that only occur in context of other disorders, specifically Attention-Deficit/Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD), or Developmental Coordination Disorder (DCD). Little research has been done to examine symptom overlap and comorbidities between NVLD and these disorders. Furthermore, some researchers have pointed out that the way NVLD is commonly understood in the clinical literature seems quite similar to the construct of Deficits in Attention, Motor Control, and Perception, otherwise known as the DAMP Syndrome, which has been in clinical use in Scandinavia since the 1970s. In the current study, we explored whether NVLD is a “standalone” disorder in a sample of youth and adults (n = 136), who have a probable diagnosis of NVLD.

Current Study: Data were drawn from a comprehensive two-part online survey. All data were obtained via caregiver-report. Caregivers were asked to complete the Five-to-Fifteen-Revised Questionnaire (5-15R), a comprehensive instrument that assesses childhood development and behaviors which map onto neurodevelopmental disorders and other common psychiatric problems in youth. They were also asked to provide information on their child’s mental health treatment history and lifetime psychiatric diagnoses, and to complete the NVLD “Symptoms” Questionnaire. We conducted a Latent Class Analysis (LCA) on data extracted from the 5-15R to examine whether different classes, or symptom profiles, emerged among the sample, and compare classes on their receipt of mental health treatment, psychiatric diagnoses and problems, and NVLD symptoms.

Hypotheses: We hypothesized that different classes, or symptom profiles, would emerge among the sample, that problems with perception would be common theme across classes and that one class would emerge that only had problems with perception.

Methods: In addition to the LCA, we ran frequency distributions on demographics, mental health treatment, and psychiatric problems and diagnoses on the overall sample and Chi-Square Tests of Independence to examine the association between class and the aforementioned variables. We conducted One-Way ANOVAs to examine whether the classes differed in terms of their level of NVLD symptoms. We also conducted Independent Samples T-Tests to determine if any one specific neurodevelopmental disorder predicted a higher level of NVLD symptoms.

Results: Overall, the subjects in the sample had a plethora of mental health problems. The LCA identified four qualitatively different latent classes, two of which fit the NVLD and DAMP Syndrome profiles, and two of which did not fit either. The two classes which seemed the most consistent with NVLD contained subjects who had the highest probability of having problems with perception and the highest level of visuospatial deficits, which exceeded the other aspects of DAMP. Although Speech/Language Disorder, DCD, and Sensory Integration Problems predicted a higher level of NVLD symptoms, we found that NVLD symptoms are not better explained by other neurodevelopmental disorders. These findings suggest that NVLD might be considered a discrete neurodevelopmental disorder with a high likelihood of comorbidity with other neurodevelopmental disorders, and in some instances individuals diagnosed with NVLD may fit the DAMP Syndrome profile.

Conclusion: Individuals with NVLD represent an important clinical group. However, not all individuals who have an NVLD diagnosis have visuospatial deficits. More research is necessary to explore the overlap between NVLD, verbal deficits, and ADHD subtypes.