Effects of l-amphetamine sulfate on cognitive function in multiple sclerosis patients

Area of Science:

• Neuroscience
• Pharmacology
• Clinical Neurology

Background:

• Multiple sclerosis (MS) frequently causes cognitive impairment, particularly slowed processing speed.
• Current treatments for MS-related cognitive dysfunction are limited.
• Amphetamine enantiomers are stimulants with potential cognitive-enhancing properties.

Purpose of the Study:

• To investigate the effects of the levo (l) enantiomer of amphetamine sulfate on cognitive function in patients with MS.
• To determine dose-dependent effects of l-amphetamine on processing speed and memory.

Main Methods:

• A counterbalanced, within-subjects, placebo-controlled study.
• 19 MS patients received single doses of placebo, 15 mg, 30 mg, or 45 mg of l-amphetamine.
• Neuropsychological tests assessing processing speed and memory were administered as primary outcomes.

Main Results:

• Significant improvements in processing speed were observed at the 45 mg dose of l-amphetamine.
• The Symbol Digit Modalities Test, measuring visual processing speed and working memory, showed the largest treatment effect.
• While episodic memory showed trends in the expected direction, results were not statistically significant.

Conclusions:

• Preliminary findings suggest that l-amphetamine may be a promising symptomatic treatment for slowed mental processing in MS.
• Further rigorous placebo-controlled trials are warranted to validate these results and establish efficacy.
• L-amphetamine could offer a novel therapeutic option for cognitive deficits in multiple sclerosis.