The research, which draws on over 60 pre-existing, peer-reviewed studies into topics spanning isolation, loneliness and mental health in young people aged 4 to 21, has been published in the Journal of the American Academy of Child and Adolescent Psychiatry.
"From our analysis, it is clear that there is strong association between loneliness and depression in young people, both in the immediate and the longer term," said study lead author Dr Maria Loades from the University of Bath in England.
According to the review, young people who are lonely might be as much as three times more likely to develop depression in the future, and that the impact of loneliness on mental health could last for at least 9 years.
There is also evidence that the duration of loneliness may be more important than the intensity of loneliness in increasing the risk of future depression among young people.
This should act as a warning to policymakers of the expected rise in demand for mental health services from young people and young adults in the years to come - both here in the UK and around the world, said the researchers.
"There is evidence that it's the duration of loneliness as opposed to the intensity which seems to have the biggest impact on depression rates in young people.
"This means that returning to some degree of normality as soon as possible is of course important. However, how this process is managed matters when it comes to shaping young people's feelings and experiences about this period," " Loades said.
"For our youngest and their return to school from this week, we need to prioritise the importance of play in helping them to reconnect with friends and adjust following this intense period of isolation," she added.
According to the researchers, the easing of lockdown restrictions should be done in a way that provides all children with the time and opportunity to play with peers, in and outside of school, and even while social distancing measures remain in place.
The social and emotional benefits of play and interaction with peers must be clearly communicated, alongside guidance on the objective risks to children, the authors wrote.
Another study, published last month in BMJ Open journal, revealed that young people with severe mental distress were highest at risk of suicide.