Weight loss drug Ozempic could cut the risk of developing dementia in half and protect against other mental problems, according to a new study.

People suffering from type 2 diabetes face an increased risk of dementia.

But after a year on the drug patients were found to have a 48 per cent lower risk of the disease, compared to those who had taken an older drug called sitagliptin.

They also had a lower risk of cognitive deficits compared with those who had been on either sitagliptin or glipizide, another older medicine.

The University of Oxford study suggests Ozempic may also be protective against addiction, after those taking it were found to have a 28 per cent lower risk of smoking than those who had been taking glipizide, researchers in The Lancet’s eClinicalMedicine journal said.

It is the latest in a series of trials to show potential benefits beyond diabetes control and weight loss for semaglutide, the main ingredient in both Novo’s Ozempic and its obesity medicine Wegovy.

Most of the other benefits – to the heart, kidneys and arthritic knees – are linked to weight loss, but scientists are also studying whether the medicine can help treat alcoholism by reducing the urge to drink.

The trial did not randomly assign patients to take Ozempic or other drugs.

Instead, it relied on medical records from more than 100,000 US patients, and researchers used statistical methods to ensure they were making the most accurate comparisons possible.

A study from Denmark came to a similar conclusion after following people with type 2 diabetes for five years, finding those on semaglutide or liraglutide had a lower incidence of dementia.

More research will be needed “to find out for certain if semaglutide does have benefits to reduce cognitive dysfunction or affect smoking rates in people with diabetes,” John Wilding, a professor of medicine at the University of Liverpool who reviewed the study independently, said in a comment distributed by the non-profit Science Media Centre.

Two clinical trials, which began in 2021, are testing whether semaglutide slows the progress of the disease in people with early stage Alzheimer’s. They are due to finish in 2026.

Semaglutide, the ingredient in Ozempic, acts as an insulin regulator, helping the pancreas to release the correct amount of insulin when blood sugar levels are high.

But there are no known receptors for semaglutide in the region of the brain responsible for memory, so it is not fully understood how the drug could treat dementia.

Writing in The Conversation, two Oxford academics said its effect on neuroinflammation could be key.

Semaglutide is believed to be anti-inflammatory and neuroinflammation damages the blood-brain barrier, they said, which is disrupted in both Alzheimer’s disease and vascular dementia.