Clyde is unmarried and has few friends. Why is he at greater risk for developing coronary heart disease than the general population?

Social isolation has been associated with increased risk of the disease.

Explanation:

In a study conducted where there were 480,000 adults in the UK a person's health and social life were taken into account. Their life was monitored over a a span of seven years. They noted that those who had weaker social networks developed cardiovascular issues while those that had stronger social networks did not show cardiovascular issues.

In the end the conclusion drawn was that social isolation lead to greater risk for developing coronary heart disease.