Looking anew at cognitive dysfunction in multiple sclerosis: The gorilla in the room

Inattentional blindness refers to a phenomenon in which individuals fail to notice an object in plain sight. Present in healthy, cognitively intact individuals, it has not been studied in patients with MS in whom it could theoretically act as a marker for real-world cognitive difficulties in those deemed cognitively intact on conventional neuropsychological batteries. Our hypothesis was that difficulty sustaining attention in patients with MS would paradoxically be associated with less inattentional blindness. A cross-sectional study was undertaken in which a consecutive sample of 68 patients with MS completed neuropsychological testing with the Minimal Assessment of Cognitive Function in Multiple Sclerosis (MACFIMS) battery. Two additional tests were administered, the Stroop Test and a measure of inattentional blindness, i.e., the gorilla in the room paradigm. The gorilla test elicited 2 variables: the ability to detect the gorilla and the number of times a ball was passed between members of one team. Cognitive dysfunction by MACFIMS criteria was present in 36.8 of subjects. There were no differences between patients with MS and healthy control subjects on the gorilla indices. Similarly, no inattentional differences were present between cognitively intact and impaired patients with MS. However, patients with MS who were impaired on the Stroop and 2-second Paced Auditory Serial Addition Test were more likely than their intact counterparts to detect the gorilla (p = 0.038 and 0.014, respectively), with Stroop-impaired patients detecting fewer ball passes (p = 0.002). The results support our hypothesis that less inattentional blindness is associated with heightened distractibility. This may explain why some patients with MS deemed cognitively intact on a battery of tests such as the MACFIMS still struggle with real-world challenges such as multitasking and filtering distracting stimuli.