What is the most effective way to reduce loneliness?

As the authors of a study just published in the Personality and Social Psychology Review state:

"Social and demographic trends are placing an increasing number of adults at risk for loneliness, an established risk factor for physical and mental illness."

They undertook an examination of the four most common intervention strategies: a) improving social skills, (b) enhancing social support, (c) increasing opportunities for social contact, and (d) addressing maladaptive social cognition. Social cognition refers to how people see, think and feel about themselves and their fellow human beings. They conducted their investigation by using...

"An integrative meta-analysis of loneliness reduction interventions...to quantify the effects of each strategy and to examine the potential role of moderator variables."

What did the data show? Changing social cognition—negative perceptions of oneself and/or others—was by far the most effective:

"...the most successful interventions addressed maladaptive social cognition. This is consistent with current theories regarding loneliness and its etiology."

In other words, it was more important and successful for the subjects to change their thoughts and judgments about themselves and others than it was to have them to spend more time with others, improve their social skills, or enhance social support.