Spending just 10 minutes a day talking to dementia sufferers about their interests or family could help improve their quality of life, according to a study.
Researchers carried out a nine-month trial in 69 care homes in England.
One-to-one interaction, combined with personalised care, significantly reduced the residents' anger and agitation, the study found.
The authors said other homes should try taking a more "personal" approach.
'Simple things… implemented robustly'
The study, published in PLOS Medicine, involved more than 800 people with dementia across care homes in south London, north London and Buckinghamshire over a nine-month randomised controlled trial.
Staff in the homes were trained to learn about their patients' interests and abilities and ask them and their families questions about the care they received.
This led to care that was more personalised and incorporated an hour a week of social interaction.
This could range from conversations about a patient's family, or interests such as sport, to helping them take part in activities like gardening or music.
The study found improvements in quality of life, agitation, and neuropsychiatric symptoms, with the greatest benefits for people with moderately severe dementia.
Prof Clive Ballard, of the University of Exeter medical school, who led the research, told the BBC: "Often there's a lot of nihilism around dementia, that people think that it's really awful, which it is, but think there's nothing you can do about it.
"I think what this is suggesting is that actually relatively simple things, if implemented robustly, can actually make a real difference to people's quality of life."
Prof Ballard said in many care homes residents receive as little as two minutes of social interaction a day.
He said in many care homes social activities were done in groups, such as with bingo, which often left a number of residents unengaged.
Interacting with them, and learning about their interests and abilities, not only improved the quality of their lives but also made them easier to deal with, he said.
Prof Ballard said this could ultimately help reduce costs, both in care homes and the wider social care system.
However, the study also highlighted problems with training in the care sector, Prof Ballard said.
He said there were currently 170 carer training manuals available, but only four were based on evidence that really worked, with manuals often used because of their cost, rather than efficacy.
"That is simply not good enough – it has to change," he said.
Dr Doug Brown, director of research at the Alzheimer's Society, said: "This study shows that training to provide this type of individualised care, activities and social interactions can have a significant impact on the wellbeing of people living with dementia in care homes.
"It also shows that this kind of effective care can reduce costs, which the stretched social care system desperately needs."
Researchers said future work should look at how sustainable the treatment would be for care homes across the country.
Dr Sara Imarisio, head of research at Alzheimer's Research UK, said: "With 850,000 people living with dementia in the UK and that number set to rise, it is important that research into new drugs is coupled with other approaches that can help transform people's lives."