Treatments for mental illnesses should help people’s ability to work and contribute as effective members of society. For example, studies often compare the effectiveness of different therapies. If research shows that people with a disorder, such as depression, are less likely to suffer a relapse after having CBT then, even though CBT might initially be more expensive than drug therapy, in the long-term it might be more economically sound to offer cognitive therapy as people would have less time off work.