In life, the human animal may be like a tree — growing in concentric circles but, at the core, the same as always.

A new longitudinal study finds that people who are more outgoing and emotionally stable in young adulthood tend to enjoy greater happiness and health later in life.

Researchers from the United Kingdom examined the effects of extroversion and neuroticism at ages 16 and 26 on mental wellbeing and general happiness later in life at 60 and 64, also exploring the effects of mental health on the body.

Led by Catharine Gale from the University of Southampton, investigators from the University of Edinburgh and the University College London found that personality traits during teenage and early adult years leave an enduring influence on psychological health decades into the future.

"Few studies have examined the long-term influence of personality traits in youth on happiness and life satisfaction later in life," Gale told reporters. "We found that extroversion in youth had direct, positive effects on wellbeing and life satisfaction in later life."

By contrast, neuroticism left a negative impact, leaving people more susceptible to anxiety and depression but also to physical health problems later in life.

The researchers pored over data on more than 4,500 study participants in the National Survey for Health and Development, conducted by the Medical Research Council. All in the cohort were born in 1946 and had answered survey questions at the ages of 16 and 26.

The personality inventory measured extroversion with queries about sociability, energy, and activities, whereas neuroticism was assessed with questions about emotional stability, mood, and distractibility. Decades later, the sexagenarians — more than 2,500 of them — answered a series of questions assessing their wellbeing and level of satisfaction with life, as well as their mental and physical health.

The results were pretty clear. Greater levels of extroversion in younger life were directly associated with higher scores for wellbeing and life satisfaction in later middle age. By contrast, the more neurotic types proved more susceptible in later life to emotional distress, and reported, to a smaller degree, poorer physical health.

"Understanding what determines how happy people feel in later life is of particular interest because there is good evidence that happier people tend to live longer," Gale said. "In this study we found that levels of neuroticism and extraversion measured over 40 years earlier were strongly predictive of well-being and life satisfaction in older men and women."

Personality in youth appears to impart an indelible effect on happiness in the ensuing decades, she said.

Source: Gale R. Outgoing People Lead Happier Lives. Journal of Research in Personality. 2013.