More than one in five adults said they experienced a complete breakdown in a relationship at home or at work in the past year, the UK’s largest study of social ties during the pandemic has revealed.

Younger people were more likely to have their relationships affected, with experts saying it showed the disproportionate effect of the pandemic on this age group. They added that job losses and anxiety over finances could have played a role, as well as the inability to see people outside their household during the lockdown.

A quarter of people reported worsening relationships with their spouse or partner and a quarter reported difficulties with colleagues or co-workers, according to University College London’s Covid-19 Social Study. More than one-fifth (22%) of adults experienced a complete breakdown of a relationship with either family, friends, colleagues or neighbours.

Launched in the week before the first lockdown started, the ongoing study showed that adults aged 18-29 were most likely to report a relationship breakdown – 35% compared with 12% of adults aged 60 and over.

However, it was not all bad news, as nearly half (46%) of young adults said the quality of their relationships with their spouse or partner had been better than usual over the past year. This is a higher proportion than in adults aged 30-59 and those aged 60 and over, with 27% and 21% of these age groups reporting a better relationship with their spouse or partner respectively.

The study is being funded by the Nuffield Foundation, with additional support from Wellcome and UK Research and Innovation (UKRI). It has had more than 70,000 participants, who have been followed across the past 72 weeks.

The study’s lead author, Dr Elise Paul from the UCL Institute of Epidemiology & Health, said the report showed “the mixed impact of the Covid-19 pandemic”. She added: “Younger adults reporting a better relationship with their spouse or partner may have benefited from furlough or remote working allowing them to spend more time together.

“On the other hand, the stress of the pandemic and lockdown measures which prevented people from seeing those outside their household may have contributed to the breakdown of other relationships, particularly those with people who do not live close by.”

Paul said groups that were less affected, particularly older people, were less likely “to face anxiety over job losses and finances”.

“Again, this shows the disproportionate impact of the pandemic on those whose lives were changed the most, whether through the curtailing of an active social life, or the stress of frontline roles or insecure employment.”

The proportion of people concerned about catching or becoming seriously ill from Covid-19 increased over the two months preceding the end of the third lockdown to a height of 36%, but appears to be decreasing again and is now at 31%, although more data will be needed to confirm this trend.

Cheryl Lloyd, the education programme head at the Nuffield Foundation, said: “Younger adults are not only more likely to have reported a relationship breakdown than older age groups but, in recent months, they are also more likely to have reported concerns about catching or becoming seriously ill from Covid-19, worries about their finances and lower levels of life satisfaction. This research is well placed to inform policy decisions by providing valuable insights into the particular challenges different generations continue to face.”

The study team is also running an international network of researchers from over 70 countries. Through the network, dozens of scientists and clinicians are collating results from mental health studies running in countries around the world.