Association between anti-depressants drugs on the progression of multiple sclerosis.
Researchers found no evidence to suggest that exposure to the antidepressants ‘selective serotonin reuptake inhibitors’ were associated with a delay in MS disability accumulation or progression.
Patients with multiple sclerosis (MS), a chronic inflammatory and degenerative disease of the brain and spinal cord, are at risk of increased disability over time.
Selective serotonin reuptake inhibitors (SSRIs) are a class of antidepressants, and fluoxetine is one of the most commonly prescribed SSRIs. It has been suggested that fluoxetine can reduce the loss of nerve fibers by increasing brain blood flow and promoting the growth of support cells. This raises the question of whether fluoxetine, or the other SSRIs, could delay progression of disability in MS. In this study, researchers investigated the potential of the SSRI drugs to combat disability accumulation and the onset of secondary progressive MS.
Methods: A nested case-control study
The researchers used a nested case-control study design. This means that the researchers selected, from a large pool of MS patients, all individuals with disability accumulation or who had reached a secondary-progressive disease course. These individuals were the ‘cases.’ The ‘control’ group consisted of a carefully selected set of individuals who had not reached this level of disability or secondary progression, yet were similar in many other ways (including age, sex and other factors). For both cases and controls, the researchers then looked back to see if the patients had previously been exposed to SSRI drugs, and if there were associations between SSRI drugs and disability accumulation or onset of a secondary progressive disease course.
One important strength of this study was the availability of provincial health databases in which information was collected in real time, as it happened, and therefore avoiding the risk of ‘recall bias.’ Recall bias can happen when people forget or recall information differently depending on whether they were a case or control. The researchers were also able to access, in an anonymized form, all prescriptions filled, including those for an SSRI. Additionally, researchers accessed data from the British Columbia MS clinical database, which provided MS specific information on a large number of patients who were treated by neurologists specializing in MS.
Key Study results: No evidence was found to suggest that SSRIs delayed disability accumulation or progression of MS.
Researchers did not find evidence to suggest that the SSRI class of drugs delayed MS disability accumulation or the onset of secondary progressive MS.
While findings were somewhat similar for fluoxetine, the researchers concluded that they could not rule out the possibility that this particular SSRI might have a beneficial effect. These observations could motivate further investigation of this SSRI in MS.
Zhang T, Kingwell E, De Yong H, Zhu F, Zhao Y, Carruthers R, Petkau J, Gustafson P, Oger J, Tremlett H. Association between selective serotonin reuptake inhibitors use and multiple sclerosis disability progression. Pharmacoepidemiology Drug Safety. 2016 May 23. doi: 10.1002/pds.4031. [Epub ahead of print]
This study involved researchers from the University of British Columbia’s Pharmacoepidemiology in Multiple Sclerosis research group in the Faculty of Medicine and Centre for Brain Health and the Department of Statistics.
Dr Tingting Zhang undertook this work as a Post-Doctoral Fellow funded by the MS Society of Canada in the laboratory of Professor Helen Tremlett, Canada Research Chair in Neuroepidemiology and Multiple Sclerosis. Web-site: http://epims.med.ubc.ca/