According to the study, brain function in the hippocampus--brain area associated with memory, emotions and motivation--markedly declines with age, even in the absence of dementia. Exercise and social ties are known to preserve memory in this region in people.
"Our research suggests that merely having a larger social network can positively influence the ageing brain," said lead researcher Elizabeth Kirby from the Neurological Institute at Ohio State University-Columbus, the US.
In the study, published in the journal Frontiers in Aging Neuroscience, the team studied two groups of mice aged between 15-18 months for three months, when their natural memory declines.
While one group lived in pairs, which Kirby refers to as the "old-couple model", the other group lived with six other roommates, a scenario that allowed for "complex interactions".
Their memory was tested by making the mice recognise a toy, such as a plastic car which had been moved to a new location.
The results showed that mice who were living in a group had better brain health and memory.
"With the pair-housed mice, they had no idea that the object had moved. The group-housed mice were much better at remembering what they'd seen before and went to the toy in a new location, ignoring another toy that had not moved," Kirby said.
Further, examining the brain tissue of the mice showed increased inflammation in the pair-housed mice--a biological evidence of eroded cognitive health.
"The group-housed mice had fewer signs of this inflammation, meaning that their brains didn't look as 'old' as those that lived in pairs," Kirby said.
Future research should explore the molecular explanations for the connection between socialisation and improved memory and brain health, she noted.