Researchers at the Oxford Internet Institute said their study was the largest of its kind and found no evidence to support "popular ideas that certain groups are more at risk" from the technology.
Institute’s lead boffin ’Andrew Przybylski said that the data necessary to establish a causal connection was "absent" without more co-operation from tech companies.
If apps do harm mental health, only the companies that build them have the user data that could prove it, he said.
"The best data we have available suggests that there is not a global link between these factors," said Przybylski, who carried out the study with Matti Vuorre, a professor at Tilburg University.
Because the "stakes are so high" if online activity really did lead to mental health problems, any regulation aimed at addressing it should be based on much more "conclusive" evidence, he added.
In their paper Global Well-Being and Mental Health in the Internet Age Przybylski and Vuorre studied data on psychological wellbeing from 2.4 million people aged 15 to 89 in 168 countries between 2005 and 2022, which they contrasted with industry data about growth in Internet subscriptions over that time, as well as tracking associations between mental health and internet adoption in 202 countries from 2000-19.