More than 445,000 Australians are currently living with the effects of a stroke while an estimated one in four people will suffer one during their lifetime.

Rehabilitation has traditionally focused on physical recovery and speech therapy, not so much the ability to once again remember, understand, learn, reason and judge.

Experts however feel a change in approach is overdue.

An international collaboration led by the University of NSW's Centre for Healthy Brain Ageing is delving into what happens to cognitive function after a stroke and which risk factors lead to faster cognitive decline.

While post-stroke loss of mental function is common, research coordinator Jess Lo says she and her colleagues want to determine the trajectory and full extent of the change in cognitive performance of survivors over time.

By analysing datasets from cohort studies, they hope to better understand the determinants of decline and dementia after stroke, as well as improve the diagnosis and treatment of disorders.

The group has examined nine Stroke and Cognition Consortium studies across seven countries including Australia and the United States as well in Asia and Europe.

Some 1488 stroke patients with ischaemic stroke and a mean age of 66 were included in the study and patients were followed up for a median of three years.

"We discovered the cognitive function of stroke survivors improves for a short period soon after a stroke and then decreases, beginning from around one year post-stroke," Ms Lo said.

"The decline in stroke patients was small but faster than that of individuals without stroke and those with a second stroke during follow up had a much faster rate of cognitive decline."

"We also found the decline in older stroke patients ... happened more quickly."

The biostatistics expert says the results have implications for the design of clinical trials of therapies to prevent or slow post-stroke cognitive decline.

They could also help clinicians better understand and plan for long-term patient needs.