Validity of visuospatial memory tests in pediatric Multiple Sclerosis

Visual-Cognitive Processing Deficits in Pediatric Multiple Sclerosis

Multiple Sclerosis (MS) is thought to be an autoimmune disorder which affects the central nervous system. According to the National Pediatric MS Center, in MS, myelin is lost in multiple areas, leaving scar tissue called sclerosis. When myelin or the nerve fiber is destroyed or damaged, the ability of the nerves to conduct electrical impulses to and from the brain is disrupted, and this produces the various symptoms of MS. One of these symptoms is cognitive dysfunction. According to the National Pediatric MS Center, approximately 50% of individuals with MS will develop problems with cognition. While the disorder is typically diagnosed in individuals between the ages of 20 and 30, approximately 5% of the cases diagnosed are children (National Pediatric MS Center). Additionally, the National Multiple Sclerosis Society reports that 2% to 5% of adult patients with MS report having symptoms prior to age 18.

There are several challenges unique to the assessment and treatment of children with MS. First of all, because the symptoms of MS are similar to other childhood disorders, it is difficult to diagnose (National Multiple Sclerosis Society). Additionally, children may experience symptoms such as seizures and mental status changes that are not present in adults with MS (National Multiple Sclerosis Society). Finally, Smerbeck et al. (2011) report that cognitive impairments may be more significant in children than adults with MS because the central nervous system is still developing. Language impairment and verbal intelligence are particular concerns (Smerbeck, et al.). Therefore, valid and reliable assessment tools are crucial for identifying these cognitive impairments in children with MS. This paper will review a study designed to evaluate the validity of two such assessments.

Purpose of Research Study

According to Hubley (2010) the Brief Visuospatial Memory Test-Revised (BVMTR) is designed to measure visuospatial learning and memory in adults. The purpose of the Symbol Digit Modalities Test (SDMT) is to provide a screening tool for detecting patients, children as well as adults, who have disease, damage, or dysfunction implicating the cerebral hemispheres (Reed, 2010). The purpose of the research study conducted by Smerbeck et al. (2011) was to determine the sensitivity and validity of these instruments in assessing cognitive impairments in pediatric Multiple Sclerosis.

Conclusions of Study

The study found that MS patients performed "significantly worse" than the healthy participants on both the BVMTR and the SDMT (Smerbeck, et al., 2011). Smerbeck et al. report that the MS participants scored almost 1 standard deviation below control participants on the BVMTR and 0.69 of the standard deviation lower on the SDMT. According to Smerbeck et al., these results support their hypothesis that "pediatric MS patients achieve significantly lower scores than typically developing controls on tests of visual processing speed and memory" (p. 453). The researchers concluded that the BVMTR and the SDMT could be used in detecting and monitoring pediatric patients with MS.

Implications of Study

Smerbeck et al. (2011) explain that cognitive impairments are a significant burden for children with MS. In order for teachers and other educational professionals to provide accommodations or remediation to address these impairments, the impairments have to be identified. Smerbeck et al. suggest that due to the ease of administration and scoring as well as the ability to repeat the assessments over time due to multiple forms, the BVMTR and SDMT are effective tools for this purpose. Additionally, the instruments may be used to monitor cognitive performance over time.

Ethical Issues Involved in study

The American Psychological Association's (APA, 2010) Code of Ethics provides several guidelines for use in conducting research and assessment. First of all is the requirement of informed consent. According to the APA, informed consent includes an explanation of the nature and purpose of the assessment, fees, involvement of third parties, and limits of confidentiality and sufficient opportunity for the client/patient to ask questions and receive answers. The second ethical issue is releasing of test data. Researchers are required to maintain confidentiality of individual's test results unless required by law to release the results (APA). Additionally, researchers are required to take into account the purpose of the assessment as well as the various test factors, test-taking abilities, and other characteristics of the person being assessed, such as situational, personal, linguistic, and cultural differences, that might affect psychologists' judgments or reduce the accuracy of their interpretations when interpreting test results (APA). In order to alleviate these differences, the researchers in this study excluded participants who were limited English speakers, or who had other cognitive impairments that would impact their results.

Your Reactions to and Critique of the Study

The study was conducted with an adequate sample of diverse participants. Additionally, researchers were careful to match MS participants with demographically similar healthy participants. However, the researchers of the study provided several limitations of the study. The first limitation is the absence of an external criterion for impairment (Smerbeck, et al., 2011). One such external criterion could be academic achievement. The study would have been stronger had it provided academic achievement data for the participants to determine the impact of the cognitive impairment. The second limitation, according to Smerbeck et al., is that the results of the BVMTR may have been impacted by fine motor coordination deficits. Smerbeck et al. suggest that this limitation could be overcome in future studies by including a measure of fine motor skills. Finally, Smerbeck et al. acknowledge that impairment in the oculomotor system may have impacted the particpants' performance on the SDMT.

Relevant Questions

One of the questions this writer has for the researchers relates to the length of time since the diagnosis of MS of the study participants. One of the concerns and one of the suggested future uses of the assessments, identified by the researchers is the fact that it did not identify how the cognitive impairments accumulate over time (Smerbeck, et al., 2011). This leads to several questions. Are cognitive impairments impacted by the age of onset of the disorder? Are there critical periods of brain development in which the onset of MS will have more of an impact on cognitive impairment?