Sunday, June 14, 2015

Happiness and the aging brain

In 2008, the Gallop organization randomly called around 355,000 people in the United States, asking them about their state of happiness.  They wanted to quantify how this state changed as people transitioned from youth, to middle age, to old age.  To assess global well-being, they asked the following:

“Please imagine a ladder with steps numbered from 0 at the bottom to 10 at the top.  The top of the ladder represents the best possible life for you, and the bottom of the ladder represents the worst possible life for you.  On which step of the ladder would you say you personally feel you stand at this time?”

They found that youngest people, those in their late teens and early 20s, felt quite upbeat about their life, placing themselves high up on the ladder.  Unfortunately, this sense of well-being dropped as age increased, reaching its lowest point around the age of 50.  But as age increased beyond 50, the sense of well-being increased dramatically, continuing to grow even into the 8th and 9th decade of life. 
Well-being ladder as a function of age in America, as assessed in 2008
The trend was consistent in both men and women.  And so amazingly, people in America felt that they reached their lowest point on the ladder of life around the time they reached midlife.  What is it about aging beyond the teen years that made people feel worse about their sense of well-being, and why did this process reverse in the fifth decade of life?

Stress and worry decline in mid life

Statistical analysis of the data revealed that some obvious things that one might think affects sense of well-being did not alter the age-dependent process.  For example, gender, being unemployed, having a child living at home, and not having a partner had no significant effects on the trends.  That is, regardless of these factors, people simply became less happy as they aged toward midlife, and then something seemed to change, allowing them to regain happiness as they got older.

The authors of the study, writing in the Proceedings of the National Academy of Science, speculated that perhaps this change had something to do with increased wisdom and emotional intelligence of the aged.  They wrote: “older people have an increased ability to self-regulate their emotions and view their situations positively.”

They provided some data to back their speculation.  That same Gallop poll had also asked the respondents to evaluate how they felt yesterday.  They asked about specific affects like worry, stress, and anger: “Did you experience stress during a lot of the day yesterday?  Did you experience worry during a lot of the day yesterday?”

They found that regardless of age, women reported that their yesterday had greater stress and worry than men.  However, there was a dramatic age-dependent effect.  When young people evaluated their yesterday, they reported much more stress and worry than older people.  But for people in their late 40s and early 50s, their yesterday was suddenly much less stressful than for people 10 years younger.  For people in their 60s, their yesterday was even more peaceful.

The emotional response to what could've been

This questions of why people (at least Americans) feel a reduced sense of wellbeing with age, and why this process reverses at midlife, remain unanswered.  One intriguing line of research is that with age, the brain alters how it evaluates lost opportunities.  

Stefanie Brassen and colleagues asked a group of young people (around 25 years old), a group of healthy older people (around 66 years old), and a group of late-life depressed elderly (also around 66 years old), to watch a monitor which showed 8 boxes.  Seven of those boxes contained gold, but one had a devil in it.  Boxes could be opened in sequence, and as long as the box contained gold, they could keep accumulating the reward.  But if the box contained a devil, they would lose everything.  So the participants could decide to stop and collect their gains, or continue.  Importantly, if they decided to stop, the position of the devil was revealed.  This indicated how far they could have safely continued, thereby showing them the missed opportunity.

Young people responded to the missed opportunity by being aggressive on the next trial—the greater the missed opportunity on the current trial, the greater the risk that they took on their next attempt.  Surprisingly, following a missed opportunity the depressed elderly did the same as the young people, taking a bigger risk.  However, healthy elderly did not respond this way.  Following a missed opportunity, they did not increase their risk taking.

To measure the emotional response to the missed opportunities, the authors measured skin conductance and found that this measure was modulated in the depressed elderly but not in the healthy elderly.  While these data were being collected, the authors also measured brain activity using fMRI and found that whereas all groups responded similarly to winning and losing, the main difference was in the response to a missed opportunity.  Both the young and the depressed elderly had a strong response when they observed the missed opportunity.  The healthy elderly, however, only responded to real losses, and not missed opportunities.

The data suggested that healthy aging was associated with a reduced responsiveness to lost opportunities.  When the healthy elderly made their decision, they were happy if they gained something, and did not care so much if that gain was less than optimal.  That is, they did not respond emotionally to the fact that they could have made even a better decision.

On the other hand, both the young folks and the depressed elderly responded emotionally once they found out that they could have made a better decision, despite the fact that the decision that they had made had produced a gain.  That gain, in retrospect, was not good enough.  And in some ways not being as good as it could have been felt like a loss to the young folks and the depressed elderly.

So it is possible that in youth, a decision that results in a positive outcome, but represents a lost opportunity (because it could have been better), produces an emotional, stressful response. But when that same decision is made after midlife, the brain is less sensitive to the fact that the results could have been better, and more concerned with the fact that the decision produced a gain.  Curiously, this is true for elderly who are healthy, but not elderly who are depressed.  

In his poem, "The Bridge", Henry Wadsworth Longfellow writes:

For my heart was hot and restless,
      And my life was full of care,
And the burden laid upon me
      Seemed greater than I could bear.

But now it has fallen from me,
      It is buried in the sea;
And only the sorrow of others
      Throws its shadow over me.

Yet whenever I cross the river
      On its bridge with wooden piers,
Like the odor of brine from the ocean
      Comes the thought of other years.

And I think how many thousands
      Of care-encumbered men,
Each bearing his burden of sorrow,
      Have crossed the bridge since then.

I see the long procession
      Still passing to and fro,
The young heart hot and restless,
      And the old subdued and slow!

And forever and forever,
      As long as the river flows,
As long as the heart has passions,
      As long as life has woes;

The moon and its broken reflection
      And its shadows shall appear,
As the symbol of love in heaven,
      And its wavering image here.

Andrew Steptoe, Angus Deaton, Arthur A. Stone (2015) Psychological wellbeing, health and ageing.  Lancet 385: 640–648.

Stone, A. A., Schwartz, J. E., Broderick, J. E., & Deaton, A. (2010). A snapshot of the age distribution of psychological well-being in the United States.Proceedings of the National Academy of Sciences, 107:9985-9990.

Stefanie Brassen, Matthias Gamer, Jan Peters, Sebastian Gluth, and Christian B├╝chel (2012) Don’t look back in anger! Responsiveness to missed changes in successful and unsuccessful aging.  Science 336:612-614.

1 comment:

  1. Great post! Kahneman also discusses the idea of a "focusing illusions" when asking about economic gains. I'll quote: "When someone reflects on how additional income would change subjective well-being, they are probably tempted to think about spending more time in leisurely pursuits such as watching a large-screen plasma TV or playing golf, but in reality they should think of spending a lot more time working and commuting and a lot less time engaged in passive leisure "

    I suspect that by middle age, people understand the trade-off of working more for more economic gain at the loss of leisure time better than 20-somethings.