Summary

Preliminary research suggests that fluoxetine, better known as Prozac, may help patients with relapsing multiple sclerosis. In a clinical trial, those on Prozac had fewer new areas of inflammation in their brain compared to those in the control group. Prozac seems able to act in the brain to modify the autoimmune process underlying multiple sclerosis. The new findings suggest that further, larger, trials would be justified.

Introduction

Multiple sclerosis (MS) is a chronic and often unpredictable neurological disease marked by symptoms such as double vision and weakness in the limbs. It occurs because of loss of the myelin sheath which surrounds the axonal part of the nerve cells, impairing their function. The details of the pathology underlying MS are incompletely understood at present. However, a hallmark of the disease is the presence of inflammatory lesions in the brain which are detectable by magnetic resonance imaging (MRI). Researchers believe these lesions arise because of autoimmune processes involving T cells. Therefore, drugs that could inhibit this T cell function might represent a new approach to treating MS.

A team in the Netherlands, led by Jop Mostert at the University of Groningen, thinks that biochemical signalling pathways in a type of brain cell called astrocytes might be important in this context. Enhancing this pathway might help reduce MS-linked inflammation, they say. The antidepressant drug Prozac, or fluoxetine, acts by increasing levels of the mood chemical serotonin and is known, from animal studies, to boost the brain pathways that the MS researchers are interested in. Therefore, they decided to see whether Prozac can help prevent inflammatory lesions in the brains of patients with MS.

What was done

A group of 40 patients with the relapsing remitting form of MS, none of whom was suffering from depression, was enrolled into the study. They received either 20 milligrams of fluoxetine or placebo every morning for 24 weeks. They received a brain MRI at the start and every four weeks after that during the 24 weeks of the study. The number of new inflammatory lesions occurring during this time was measured.

What was found

The effects of fluoxetine became apparent after eight weeks. One in four scans of those treated with fluoxetine showed new areas of inflammation, compared to four out of ten in those on placebo. And during the last 16 weeks of the study, almost two thirds of those on fluoxetine had no new inflammatory lesions. The corresponding figure for the placebo group was 26 percent.

What this study means

These findings lend support to the theory that enhancing biochemical signalling in astrocytes damps down the inflammation underlying MS. It shows that data obtained from lab and animal studies are now reproduced in people. The reseachers say that there are additional ways in which fluoxetine can help reduce loss of axons in MS, such as production of nerve cell growth factors. The results of this study point the way towards further exploration of Proxac in MS, maybe in combination with other drugs that can modify immune activity.