The second analysis, comprising 70 studies and more than 3.4 million adult subjects, showed that loneliness, social isolation, as well as solitary living were all tied to a greater risk of early death.
The research looked at the impact of both social isolation as well as the rise of loneliness, which is expected to continue to rise in the future.
Researchers believe loneliness is so deadly because it can lead to a number of issues, including disrupted sleep patterns, high levels of stress hormones, increased inflammation, and worsening immune systems. Doctors can also play a role in alerting older patients to the risks of loneliness, and offer ways to combat its effects.
To assess the extent of this phenomenon in other regions of the world and the public health hazard it represents, Holt-Lunstad and colleagues conducted two meta-analyses.
An American Association of Retired Persons' (AARP) study by the name "Loneliness Study" estimates almost 42.6 million adults in United States, who are above 45 years old, as suffering from chronic loneliness.
Holt-Lunstad added that an increasing portion of the US population is now experiencing isolation on a frequent basis. Further, the latest census data shows that over 25% of the country's population lives alone, that more than half of the total population is unmarried, and that marriage rates and the number of kids per household have dropped.
These trends toward solitude "suggest that Americans are becoming less socially connected and experiencing more loneliness", said Holt-Lunstad.
Other recent studies have echoed Dr. Holt-Lunstad's findings and pointed to the growing use of social media as a possible cause.
In an effort to explain how loneliness could trump obesity as a health risk, Holt-Lunstad brought up two meta-analyses - not actual studies, but rather a combination of data across several studies - at this week's American Psychological Association convention. The first one included 148 studies represented over 300,000 participants, by which it was found that, greater social connection is linked with a 50% decrease in risk of premature mortality. The conclusion: The effect of the three was equal to or greater than well-known risk factors such as obesity. "With an increasing aging population, the effect on public health is only anticipated to increase", the professor said.
She suggested greater priority be placed on research and resources to tackle loneliness such as social skills for children in schools.
Councils should also ensure there are sufficient social spaces that encourage gathering and interaction, such as recreation centers and community gardens.