Preliminary evidence that caffeine improves attention in multiple sclerosis.

There are no licensed drugs to boost cognitive performance in multiple sclerosis (MS). Here, we provide preliminary evidence that caffeine can improve attention in people with MS. Participants were tested on three different metrics of attentional functioning [choice reaction times, Stroop performance and a Rapid Serial Visual Presentation (RSVP) task] repeated across four sessions (baseline, one week after caffeine abstention and two sessions on days 8 and 9 where participants were pseudorandomized to receive counterbalanced caffeine or decaffeinated products). The administration of caffeine, compared to decaffeinated substances, was found to selectively reduce the 'attentional blink' in MS patients. There was no evidence that caffeine administration significantly affected performance on the Stroop or choice reaction time tasks. However, in contrast to other metrics of attention used in this study, there was evidence that Stroop performance declined on day 7 compared to day 1, an effect perhaps due to caffeine withdrawal. Cumulatively, these results suggest that caffeine can act as a cognitive enhancer in MS but may only benefit patients under situations of high attentional demand (RSVP dual task). Interestingly, there may be long-term positive effects of caffeine on cognition in MS that are only exposed following sustained abstinence periods.