Adopting a handful of positive lifestyle habits could make the brain up to eight years younger, according to new research.

Scientists at the University of Florida found that optimism, getting enough deep sleep, managing stress and having strong social support were linked to a younger–looking brain on scans.

The study tracked 128 adults in midlife and older age from four continents over a two–year period. Nearly 70 per cent of participants were women, and most were living with chronic pain related to, or at risk of, knee osteoarthritis.

Using advanced MRI scans and machine learning techniques, researchers estimated each participant's 'brain age' and compared it with their actual age. 

Those who reported the healthiest mix of psychological and lifestyle factors had brains that appeared up to eight years younger than expected.

In contrast, a number of hardships were linked to brains that appeared older, including chronic pain, lower income, lower levels of education and social disadvantage.

However, the researchers found that while the impact of hardship on brain ageing weakened over time, the benefits of positive lifestyle factors were stronger and more long–lasting.

Other behaviours linked to healthier brain ageing included avoiding smoking and maintaining a healthy body weight.

'The message is consistent across our studies,' said Kimberly Sibille, an associate professor of physical medicine and rehabilitation at the University of Florida, who led the research.

'Health–promoting behaviours are not only associated with lower pain and better physical functioning. They appear to actually bolster health in an additive fashion at a meaningful level.'

The findings were published in the journal Brain Communications.

The study adds to growing evidence that mental wellbeing and lifestyle choices play an important role in brain health, even in people dealing with chronic pain or long–term health conditions.

The findings come as separate research suggests that certain personality traits may influence how long people live.

In a large analysis led by researchers at the University of Limerick, scientists examined data from more than half a million people, covering nearly six million person–years. During the study period, 43,851 participants died.

The team looked at five major personality traits – neuroticism, extraversion, openness, agreeableness and conscientiousness – and how they related to the risk of death.

People with higher levels of neuroticism, characterised by anxiety and emotional instability, had a three per cent higher risk of dying earlier.

By contrast, higher conscientiousness – associated with being organised, disciplined and dependable – was linked to a ten per cent lower risk of death.

Extraversion, reflecting sociability and engagement with others, was linked to a three per cent lower risk of death, with the effect particularly strong in the United States and Australia.

No clear link was found between mortality and either openness or agreeableness.

'Our work shows that how we think, feel and behave is not only linked to life satisfaction and social relationships, but also to how long we live,' said Dr Máire McGeehan, an assistant professor at the University of Limerick who led the study.

The research, conducted in collaboration with Florida State University, West Virginia University and Northwestern University were recently published in the Journal of Personality and Social Psychology.

'Personality is a critical driver of health and longevity, with effects similar in size to commonly recognised public health factors such as socio–economic status.'

Dr Páraic S Ó Súilleabháin, a senior author on the study, said the findings would help shape future research into how psychological traits influence health across the lifespan.