The antidepressant, Prozac, may help to curb disease activity in a particular form of multiple sclerosis (MS), new research indicates.

A team of researchers followed the progress of 40 patients with the relapsing remitting form of MS.

MS is a condition which affects the brain and spinal cord. It is characterised by a slowly progressing disablement. According to the Multiple Sclerosis Society of Ireland, most people with MS start off with the relapsing remitting type. This means they have attacks followed by remissions. During remissions, they may have fewer or no symptoms. Relapses tend to be unpredictable and their causes are unclear.

The researchers randomly allocated the 40 patients to treatment with either 20mg daily of fluoxetine (Prozac) or a placebo for a period of 24 weeks.

Detailed MRI scans were carried out every four weeks to check for new areas of neurological inflammation, which is a hallmark of active MS.

The brain scans found that those in the placebo group had more new areas of inflammation, compared to those in the Prozac group.

The effects began to become evident eights weeks into the study, which corresponds to the time that SSRIs start to work on relieving depression. SSRIs (selective serotonin reuptake inhibitors) are the class of drugs to which Prozac belongs.

The average number of new areas affected was more than five in the group given the placebo, compared to just under two in the group given Prozac.

Overall, around 25% of scans from patients treated with Prozac showed new areas of inflammation, compared with 40% of those taking the placebo.

During the last 16 weeks of treatment, 63% of those given Prozac had no new areas of inflammation, compared with just 26% of those in the placebo group.

The researchers emphasised that their study was small and larger studies would be needed before firm conclusions could be reached.

However they said that their results are ‘sufficiently encouraging to justify further studies with fluoxetine in patients with MS’. They added that higher doses and treatment combinations with other drugs that alter the immune response should also be considered.

Details of these findings are published in the Journal of Neurology, Neurosurgery and Psychiatry.