 We even trust each other less than we did in the 1970s. And the effect on our bodies go far beyond just the actual feeling of loneliness. A lack of social connection can increase your risk of developing both heart disease and stroke by 30% and dementia by 50%. And loneliness throughout childhood increases the risk of developing mental health conditions such as anxiety and depression. And when it comes to premature death, loneliness is as dangerous as smoking 15 cigarettes a day.