What's the secret to health and happiness? For some, it's an optimistic spirit. Others might say your experiences are what matters, or maybe your personality is paramount.
There's no single formula, but in recent decades positive psychology has increasingly focused on the theory of well-being, encompassing our quality of life, sense of purpose and meaning, personal environment, and relationships with others.
A considerable amount of research has shown that positive well-being is linked to significant improvements in health and lifespan and may help protect mental health, including lowering your risk of depression.
But while there's much we understand about well-being, there's also a lot we don't, including how it develops as the years pass. Does well-being change over the course of decades, or is it a fixed psychological baseline, persisting into our futures?
The truth is, we don't really know, with previous research offering a mix of perspectives that don't always agree with one another.
"The extent to which adults sustain psychological well-being across decades – and the role of depression in shaping these trajectories – remains poorly understood," psychologists explain in a new study published in Nature Mental Health, led by first author and mental health researcher Cassondra Lyman from Cornell University.
"Surprisingly, little is known about what factors predict the attainment of high levels of well-being over decades."
To investigate how well-being might evolve over time and how it interacts with depression, Lyman and her co-authors analyzed data from 2,420 participants in the Americans' Changing Lives study, a longitudinal study following a nationally representative cohort that began with 3,617 adults in 1986.
Tracking multiple measures – including life satisfaction, affect, self-acceptance, mastery, and positive relationships – the researchers found participants' well-being took four distinct kinds of trajectories over the space of 25 years.
For most people in the analysis, about 60 percent, their level of well-being was generally consistent over time.
People in this group tended to report intermediate levels of initial well-being, and their well-being levels remained relatively stable, but it's worth noting that persistent well-being doesn't mean high levels – about a quarter of the group maintained persistent low levels of well-being.
The next largest group encompassed about 30 percent of the participants, people who began the study with low initial well-being but saw gradual increases in well-being over time.
A third group, representing about 8 percent of individuals, started off with high well-being that demonstrated a steep decline before leveling off.
The last segment, which only amounted to about 2 percent of the cohort, began with very low well-being, and experienced strong upward improvements, although half this group couldn't sustain their increases in well-being, which dropped off over time.
Overall, the researchers found that people's well-being at baseline was the strongest predictor of a change in the direction of their well-being (i.e., high to low, or vice versa).
"People with lower baseline well-being were more likely to experience improvements in well-being, and people with elevated baseline depressive symptoms were more likely to experience change in well-being," the researchers write.
"Thus, people with both low well-being and elevated depressive symptoms at baseline had the highest odds of experiencing marked improvements in well-being."
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One of the most promising takeaways from the study – especially for people who experience depression – is the finding that well-being can improve over time, and it's in fact more likely to do so if your well-being is low.
Among the participants studied, 57 percent of people who showed low well-being and elevated depression symptoms at baseline ended up experiencing increases in well-being over the course of the 25-year analysis.
In terms of next steps, the researchers suggest that identifying the well-being trajectories people are on could help indicate when treatment interventions might assist them, acting as a kind of screening tool to inform the selection of future therapies.
The findings are reported in Nature Mental Health.
This article was fact-checked by Rebecca Dyer and edited by Rebecca Dyer. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.