A smart peek: Processing of rapid visual displays is disturbed in newly diagnosed, cognitively intact MS patients and refers to cognitive performance and disease progression in late stages

Abstract

Background: MS can reduce the speed of information processing (IPS) leading to a variable pattern of cognitive impairment. To better understand this deficit, a separate evaluation of the sensory, cognitive, and motor speed component is required. Tests using rapid visual displays allow for assessment of separate components of information uptake. We utilized such a test to compare deficit profiles at the earlier and later stage of MS and their relation to cognitive ability and disease progression.

Method: Two groups were evaluated: "Early MS" comprised N = 24 patients with disease durations <2 years; "late MS" N = 45 with disease durations >12 years. Rapid visual displays of letters were utilized to derive individual profiles of visual information uptake according to the 'theory of visual attention' (TVA). The resulting data was then compared with measures of disability, fatigue, depression, IPS, visual-spatial ability, verbal and visual memory.

Results: In the EMS group, where cognitive impairment was the exception, three of the four main parameters of visual information uptake were already modified, i.e. processing rate C, storage capacity K, and iconic memory μ. In LMS an additional elevation of the fourth parameter, i.e., the perceptual threshold t₀ was evident. Threshold values were related to most clinical and cognitive measures.

Conclusions: An early deficit pattern of visual information uptake can be detected at a stage, when performance in tests of IPS is still well-preserved. At later disease stages, a single parameter reflecting the threshold of conscious visual perception may provide a valid estimate of cognitive performance and disease progression.

Keywords: Cognitive assessment; Cognitive impairment; Information processing speed; Multiple sclerosis; Neuropsychology; Theory of visual attention.