A new study has found that individuals who become easily stressed during early adulthood could have an increased risk of suffering from high blood pressure later in life.

To study the effect of stress on developing high blood pressure, specifically the effect of low stress resilience -- the ability to cope well with stress -- the team of researchers, from Stanford University in the US and Lund University in Sweden, used the national disease registry data of 1,547,182 18-year old men in Sweden who were obliged to enroll in the armed forces from between 1969 and 1997 up until the end of 2012.

Every man received a medical examination, compulsory for nearly everyone in the country, which included an assessment by a trained psychologist to measure their levels of stress resilience.

As part of this assessment the men were interviewed for 20-30 minutes and asked about how well they thought they would cope with the demands of army life, including taking part in armed combat. They were also asked about their daily life at school, home, or work to find out more about their emotional state.

Based on their responses the men were given a score between 1 and 9 on the stress resilience scale, with 1 indicating low resilience and 9 indicating high resilience.

The records also showed that none of the men had high blood pressure when they enrolled in the army.

Of the 1.5 million men whose records were used in the study, 93,000 were diagnosed with high blood pressure between 1969 and 2012, when the study's records began and ended. At the end of this monitoring period the average age of the men was 47, and the average age of diagnosis of high blood pressure was 49.

After analyzing the stress resilience scores and diagnoses of high blood pressure, and taking into account other factors such as weight and a family history of high blood pressure, the researchers found that there was a link between a low resilience score at age 18 and an increased risk of developing high blood pressure later on in adult life, with the men who fell in the bottom 20% of scores showing a more than 40% increased risk of going on to develop high blood pressure than those men who fell into the top 40% of scores.

The results also suggested that becoming easily stressed in early adulthood is a bigger factor in developing high blood pressure than being overweight in early adulthood, and when combining the two factors, men who had a high BMI and low stress resilience score were more than three times likely to go on to have high blood pressure than men with a normal BMI and a high stress resilience score.

As an observational study the researchers cautioned against drawing any firm conclusions from the study, but they do believe the findings suggest that an inability to cope with stress in young adulthood could have a long-term effect on health, increasing the risk of developing high blood pressure later on life.

The findings were published online in the journal Heart.