Methylphenidate may help with eye movement, processing speed in MS

Methylphenidate, a stimulant sometimes used to manage fatigue in multiple sclerosis (MS), may also ease oculomotor (eye movement) symptoms and increase how quickly the brain processes visual information, according to a pilot study by Kessler Foundation in New Jersey.

“Our findings suggest that methylphenidate could be a beneficial treatment for MS patients, particularly for those experiencing oculomotor deficits that affect their visual processing speed and, subsequently, their quality of life,” Silvana L. Costa, PhD, who led the study, said in a foundation press release.

The study, “Effect of methylphenidate on oculomotor function in individuals with multiple sclerosis: a pilot randomized placebo-controlled trial,” was published in Frontiers in Neurology and conducted with support from a National MS Society grant.

MS occurs when a misled immune system attacks the myelin sheath that protects nerve fibers, causing damage and inflammation. This results in a range of symptoms, from poor balance and difficulty walking to mental health issues and fatigue.

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When MS affects the optic nerves, which connect the eyes to the brain, it can cause problems like blurred or poor vision, but also oculomotor symptoms related to how the eyes move. Such symptoms can include strabismus (eye misalignment), eye twitching, and poor depth perception.

Methylphenidate is a stimulant often used to treat attention deficit hyperactivity disorder (ADHD). In addition to increasing attention span and helping to control behavior, it may also improve oculomotor function in people with ADHD and in healthy individuals, studies have shown.

To find out if treatment with methylphenidate could also lead to changes to oculomotor function in people with MS, Costa and her team examined data from 11 people who had taken part in a pilot clinical study testing whether methylphenidate could reduce mental fatigue.

As part of the study, patients were randomly assigned to receive daily methylphenidate or a placebo for four weeks, or about one month. After a seven-day washout period, the two groups switched, with patients initially assigned to methylphenidate receiving a placebo, and vice versa.

Among a number of assessments, the researchers measured oculomotor speed using the King-Devick (K-D) test, a two-minute task during which patients are asked to read aloud a set of numbers as quickly as possible. The time taken to read the numbers on three different cards with increasing visual complexity is averaged to obtain the K-D time.

This test was conducted at baseline, or at the study’s start, and after each of the two treatment periods. Results showed treatment with methylphenidate decreased mean K-D time from a baseline of 41.2 seconds to 37.1 seconds. The placebo had no significant effect on K-D scores. The number of errors was similar between the methylphenidate and placebo groups. 

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Methylphenidate led to improvements in children with ADHD, healthy adults

“Our finding that performance on the K-D improved while taking methylphenidate is consistent with prior studies that have demonstrated improved visual processing speed and oculomotor function in both children with ADHD and healthy adults when taking methylphenidate,” the researchers wrote.

Additional analyses showed the improvement in oculomotor speed was significantly linked to better performance on the Symbol Digit Modalities Test (SDMT), a cognitive task during which patients pair a series of geometric symbols with numbers that provides a measure of information processing speed.

However, scores in another cognitive measure called the Paced Auditory Serial Addition Test (PASAT), in which patients hear a series of single-digit numbers and are asked to verbally respond with the sum of the two most recently read numbers, were unchanged with methylphenidate compared with the placebo.

“We found that change on the K-D strongly correlated with change on the SDMT, which assesses visuomotor IPS [information processing speed], but did not correlate with change on the PASAT, which assesses auditory IPS and working memory,” the researchers wrote.

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“We observed a notable improvement in the oculomotor speed of participants during methylphenidate administration compared to the placebo,” said Timothy J. Rich, PhD, a scientist at Kessler Foundation’s Center for Stroke Rehabilitation Research and the study’s first author.

“This improvement in eye movement speed correlated directly with enhanced performance on [oculomotor] tasks, which are crucial for everyday functions,” Rich added, which suggests that, while the study was small, methylphenidate may have a role in the treatment of MS beyond managing fatigue.