People with multiple sclerosis (MS) have a nearly fivefold increased risk of developing dementia compared with those without the disease, a nationwide study in Taiwan suggests.
Treatment with disease-modifying therapies significantly reduced the risk of neurodegenerative dementias, conditions linked to the loss of brain cells.
Use of Aubagio, known generically as teriflunomide, was also associated with a 31 per cent lower risk of Alzheimer’s disease, the most common type of neurodegenerative dementia.
Researchers said the findings indicate that MS is an independent and potent risk factor for dementia in the Taiwanese population and underline the need to monitor cognitive skills early and manage other health conditions carefully.
The study used data from Taiwan’s National Health Insurance Research Database and included 10,525 people with MS and 31,575 people without MS matched for age, sex, number of visits to medical facilities and coexisting conditions.
Most participants with MS were women, accounting for 80.3 per cent of the group, with a mean age of 41.2.
Compared with controls, they had higher rates of cerebrovascular disease, rheumatologic disease, high blood pressure, high blood fats and other autoimmune conditions such as lupus and rheumatoid arthritis.
Paralysis affecting one side of the body or the legs was also more common.
Dementia was diagnosed in 71 people with MS, equivalent to 0.67 per cent, and in 99 controls, or 0.31 per cent.
This corresponded to a cumulative incidence of 739.97 versus 343.95 cases per 100,000 person-years.
Further analysis showed people with MS had about a fivefold higher risk of dementia, which remained significant after adjusting for age, sex, education level, insurance premiums, coexisting conditions and place of residence.
The increased risk was observed across several types of dementia, including Alzheimer’s disease and other neurodegenerative dementias, and persisted after excluding cases diagnosed within the first year and the first five years of follow-up.
The researchers wrote: “This study confirmed that the individuals with MS had a nearly five-fold increased risk of developing dementia as compared to those without MS, which should alert physicians to be more attentive to the risk of dementia following MS.”
They said possible explanations include demyelination, meaning damage to the protective myelin coating around nerve fibres, disruption of cognitive pathways, neuroinflammation and coexisting vascular conditions that may reduce blood flow to the brain and contribute to vascular dementia.
The researchers added: “Recent systematic reviews and large-scale data from the US reinforced our findings, showing that MS patients are at persistently increased risk for both early- and late-onset dementia even after adjusting for comorbidities, healthcare access, and demographic factors.”
