A drug used to treat type 2 diabetes is associated with a 35% lower risk of dementia, according to research.
The number of people with dementia worldwide is expected to almost triple to 153 million by 2050, with research showing that the health and social costs associated with dementia already exceed $1 trillion (£780 billion) a year.
Type 2 diabetes is one of 14 risk factors associated with a greater risk of developing dementia. Other factors include high levels of bad cholesterol, untreated vision loss, hearing loss, high blood pressure, smoking, obesity and physical inactivity.
Now, a large Korean study published in the journal BMJ suggests that a drug used to treat type 2 diabetes, called sodium-glucose cotransporter-2 (SGLT-2) inhibitors, may prevent dementia.
Previous studies have shown that SGLT-2 inhibitors can have a protective effect against dementia in older patients. However, until now it was unclear what the protective effect is in younger people and specific forms of dementia, such as Alzheimer’s disease and vascular dementia.
The academics analyzed data from more than 220,000 people with type 2 diabetes aged 40 to 69 who had health insurance in Korea and who did not yet have dementia.
Half of the participants were given SGLT-2 inhibitors, which reduce the amount of glucose the kidneys reabsorb, and the other half were given another drug, dipeptidyl peptidase 4 (DPP-4) inhibitors, which block the enzyme that helps raise insulin levels after food.
A total of 1,172 participants who had been newly diagnosed with dementia were identified during the study period.
The researchers calculated that SGLT-2 inhibitors were associated with a 35% lower risk of dementia compared with DPP-4 inhibitors. They also identified a 39% lower risk of Alzheimer’s disease and a 52% lower risk of vascular dementia associated with patients taking SGLT-2 inhibitors.
The authors cautioned that this is an observational study and therefore cannot prove a causal link, but concluded that repurposing existing drugs to treat diseases that cause dementia “has enormous potential”, although further studies are needed to confirm their findings.
Dr Jacqui Hanley, head of research at Alzheimer’s Research UK, said the data was “promising”, adding: “People living with dementia are in urgent need of effective treatments, as last week’s news of Nice’s rejection of the Alzheimer’s drug lecanemab highlighted.”
Repurposing medications that are already approved to treat dementia could speed up the process of testing them in clinical trials and also make them significantly less expensive, she said. “If we want to cure dementia, clinicians need a toolkit of treatments that target different aspects of the disease and can be used in combination. Research into repurposing medications can help us do that.”
But Prof William Whiteley, deputy director of the British Heart Foundation’s data science centre, said: “If this research were true, SGLT-2 inhibitors could almost halve the risk of some forms of dementia, which is much greater than the effect of drugs to reduce the progression of dementia, or drugs to prevent a heart attack or stroke.
“Instead, a quirk in the study design likely led to this result.”