The effect of psychological health on cardiovascular disease has long been underrated, and in fact historically ignored.

When I was studying cardiology some 40 years ago, the focus was squarely on physical fitness, with little or no attention paid to a person’s mental state. But now we know that emotions such as anger, stress, and depression, as well as circumstances such as social isolation take a heavy toll on the heart.

Fortunately, positive emotional factors can balance the negative impact; factors such as optimism, emotional vitality, life satisfaction, sense of purpose, and mindfulness will improve your heart health.

Another factor drawing a great deal of interest these days — the subject of two major studies in recent years — is gratitude. A Harvard study published this past July in JAMA Psychiatry looked at nurses and found that those who rated highest in gratitude had a lower risk of dying from all causes, especially heart disease.

Researchers looked at data from 49,275 older American nurses who participated in the Nurses’ Health Study, adjusting for socioeconomic factors, religious factors, physical health, lifestyle factors, cognitive function, and mental health. Gratitude was assessed with a six-item questionnaire that is a widely used measure of people’s tendency to experience a grateful effect.

The researchers found that after three years, 10 percent of the nurses had died. But those with the highest levels of gratitude had a 9 percent lower risk of dying during that period, compared with those with the lowest level.

This was the first study to provide empirical evidence that experiencing grateful effects is associated with increased longevity.