A new study suggests that a positive attitude can help strengthen the immune system and increase lifespan.

According to researchers at the University of Queensland, older people who focused on positive information were more likely to have a stronger immune system than their peers. The study shows that a optimistic outlook towards life is key to healthy ageing.

The small study was based on data from 50 adults, aged 65-90 years. Participants were followed for about two years.

"Despite the fact that people often think of late life as a period of doom and gloom, older people are often more positive than younger people," Dr Elise Kalokerinos, from UQ's School of Psychology. "Our research suggests that this focus on the positive may help older people protect their declining health."

The study is published in the journal Psychology and Aging.        

Previous research has shown that optimism and resilience keep old people happy, despite their deteriorating condition.

In the present study, the researchers showed participants a set of positive and negative images. The volunteers were then asked to recall the information in the pictures.

The researchers found that people who recalled more positive images had a stronger immune response than people who only focussed on negative pictures.

"Participants who recalled more positive than negative images had antibodies in their blood suggesting stronger immune systems than those of their counterparts, who did not show this positivity in memory," Kalokerinos said in a news release. "By selectively remembering the positive, older adults seem to boost their immune functioning just when they need it the most."

According to researchers, people who focus on more positive information might be able to better cope with stressful situations than other people. Stress is already known to increase risk of heart disease and cancer. So, by avoiding stress, happy adults can increase their lifespan.