Taking amphetamines could help restore brain function in older people, a new study has revealed. A new study has found that older adults who were given a small dose of the drug, which is often used recreationally, performed as well as young adults in a short-term memory test.

And their results were dramatically better after taking the stimulant, compared with a placebo. Researchers in Berlin said their findings represent the first 'proof of concept' for a link between dopamine, a neurotransmitter that helps control the brain's reward and pleasure centres, and improving brain function.

Dopamine regulates brain activity and helps support working memory, that is the ability to keep several things in mind and update them. Scientists at the Max Planck Institute for Human Development noted that on average 'older adults have less dopamine than younger adults, and also have poorer working memory'.

They set out to test whether giving older people D-amphetamine, which encourages the production of dopamine, could improve brain ability.

The team divided a group of volunteers into two groups, younger and older adults.

Both groups were given a small dose of D-amphetamine before their brain activity was measured using functional MRI scans, performed while they undertook a working memory test. The same scans were repeated after the volunteers had taken a placebo.

As predicted, D-amphetamine, which is prescribed to children with ADHD, 'greatly increased brain signal variability in older adults - and this increase co-occurred with heightened working memory performance'.

Dr Douglas Garrett, the first author of the study, explained signal variability 'represents how stable the activity in your brain is from moment to moment'.

He said: 'Perhaps surprisingly, we often find that higher performing younger adults express more signal variability in a variety of cortical regions relative to older, poorer performing adults. 'So, greater signal variability may serve as a marker of a high functioning brain.'

Dr Garrett said: 'This study shows that administering a dopamine-stimulating agent increases the variability of brain activity - particularly in older adults - and that this increase can lead to an improvement of cognitive functioning in older adults.'  But he warned, the study does not 'provide a basis for recommending that older people should take D-amphetamine'.

Ulman Lindenberger, director of the Center for Lifespan Psychology at the institute, said: 'By no means can our findings provide the basis for a recommendation that older adults should take D-amphetamine.

'Such recommedations are out of the question at present,' added Dr Garrett. 'We first need to improve our understanding of order and repeated dosage effects.'

In order for that to happen, more research is needed, they concluded. The study was published in Proceedings of the National Academy of Sciences.