Silvana Lopes Costa

Background: Visual problems are common among persons with multiple sclerosis (MS) and may interfere with the assessment of cognitive functioning using visually mediated neuropsychological tests. The current study explored visual discomfort symptoms among persons with MS compared to healthy controls (HCs), using the Visual Discomfort Scale (VDS), which measures somatic and perceptual visual discomfort symptoms that interfere with reading.Methods: Eighty-nine persons with MS and 30 HCs completed the VDS and the Symbol Digit Modalities Test (SDMT), a visually mediated test of information processing speed and gold standard for screening for MS-related cognitive dysfunction.Results: Persons with MS endorsed higher frequencies of visual discomfort symptoms, including seeing the text or background moving or fading, headache/eye soreness, blurriness/diplopia, having to re-read, and slow reading, compared to HCs. More frequent visual discomfort symptoms were associated with worse performance on the SDMT. For participants with MS reporting moderate/high levels of visual discomfort symptoms, having a longer disease duration or progressive disease courses were correlated with worse performance on the SDMT.Conclusion: It is important for clinicians to ask about specific visual discomfort problems that the patient experiences when interpreting a visually-mediated neuropsychological test such as the SDMT, especially for MS patients with longer disease duration or a progressive disease course.

We compared the California Learning Verbal Test II (CVLT II) and the Open Trial-Selective Reminding Test (OT-SRT) in assessing learning in persons with Multiple Sclerosis. One-hundred and twelve participants with multiple sclerosis performed the OT-SRT and the CVLT II on two different days. All participants completed additional cognitive tests assessing information processing speed (IPS), working memory (WM), and executive functions (EF). By definition, all participants were identified as having impaired learning on the OT-SRT (i.e., z score <−1.0); however, only 38 participants (33.9%) were identified as having impaired learning on the CVLT II (i.e., a z score <−1 total correct responses trials 1–5). The sample was thus divided into two groups, those who failed both tests (Fail-2) and those who failed only one (Fail-1). The Fail-2 group showed poorer performance on EF, WM and IPS in comparison with the Fail-1 group. On the CVLT II, the Fail-1 group showed a significantly greater improvement between trials 1 and 5, as compared with the Fail-2 group. However, the two groups performed similarly on the OT-SRT. Correlation analysis showed that EF is positively correlated with CVLT II learning slope but not with OT-SRT learning slope. The CVLT II and the OT-SRT are not equivalent tests: while the CVLT II appears to be sensitive to overall cognitive dysfunction, the OT-SRT is more sensitive to focal learning and memory impairments.

Although the integrity of the visual system is often affected in multiple sclerosis (MS), the potential relationship between the temporal dynamics of visual processing and performance on neuropsychological tests assessing processing speed (PS) remains relatively unexplored. Here, we test if a PS deficit is related to abnormalities within the visual system, rather than impaired higher-level cognitive function. Two groups of participants with MS (1 group with PS deficits and another without) and a healthy control group, matched for age and education, were included. To explore the temporal dynamics of visual processing, we used 2 psychophysical paradigms: attention enhancement/prioritization and rapid serial visual presentation. Visual PS deficits were associated with a decreased capability to detect visual stimuli and a higher limitation in visual temporal-processing capacity. These results suggest that a latent sensorial temporal limitation of the visual system is significantly associated to PS deficits in MS.