LONDON: People recovering from depression but struggling with its effect on memory, concentration and cognitive function may benefit from the stimulant modafinil, according to results of a small study published on Tuesday.

Modafinil is a generic drug usually prescribed for sleep disorders such as narcolepsy. But in a trial of modafinil versus placebo in patients recovering from depression, researchers at Britain's Cambridge University found the drug prompted significant improvements in memory and higher scores in a test.

Describing the results as promising, Muzaffer Kaser from Cambridge's psychiatry department explained how the effects of depression on brain performance in everyday life are often sidelined as both patients and doctors focus on improving mood.

"Cognitive dysfunction is an unmet need in the treatment of depression," he said. "(Family doctors) or psychiatrists often hear complaints of concentration or memory difficulties from patients with depression. Our study demonstrated that modafinil may be a feasible option."

Depression is one of the world's leading causes of disability, affecting 350 million people globally, according to the World Health Organization.

Almost all people with depression have problems with attention, concentration and memory. This cognitive impairment tends to persist even as they start to recover from depression and can make it tough for patients to get back to work or to a fully functioning life - also increasing the risk of relapse.

To test whether modafinil might help, Kaser's team asked 60 people previously diagnosed with depression to complete computerised memory, attention and planning tasks after receiving either modafinil or placebo.

The results showed that those on modafinil made fewer errors in two specific types of memory, episodic memory and working memory, both of which are important in day-to-day activities.

Barbara Sahakian, who co-led the study, said longer term studies were now needed to see if modafinil can have a positive effect in terms of people successfully returning to work following depression.