In research published in the journal Evidence Based Mental Health, a team at the University of Liverpool found that many mental health apps and online programmes lack "an underlying evidence base, a lack of scientific credibility and limited clinical effectiveness".
Simon Leigh, co-author of the study, argues that apps should be "well-informed, scientifically credible, peer reviewed and evidence based".
"The rate at which apps come out is always going to outweigh the rate at which they can be evaluated.
Mental health apps have grown in popularity at a time when psychological services have faced an increased demand and decreased resources.
Many people find it hard to access services because of geography, because of mental ill health, because of physical disability.
We've also found that, in the 50% of cases that do get to a GP, they're not able to guide mental health problems adequately."