Depression is greatest amongst the middle-aged, according to a study conducted by Dartmouth economics professor David Blanchflower and his longtime friend Andrew Oswald, an economics professor at the University of Warwick. The study concludes that happiness is based more on age than on circumstance and does not remain consistent throughout one's lifetime, but instead follows a "U-shaped" pattern.
The study, which is to be published in the Social Science and Medicine journal, concluded that one's level of happiness steadily decreases until one's mid-40s and begins to increase after one's mid-50s. This pattern appears to be independent of other factors, such as children or work.
The study examines residents from more than 70 countries over a five to six-year period. Blanchflower gathered multiple data sets and surveys that were publicly available, such as the United States General Social Surveys.
Blanchflower and Oswald also conducted their own surveys about depression. The surveys asked people to indicate whether they were "not too happy," "pretty happy" or "very happy." These responses were given numbers from one to three, with the highest number indicating that a person was "very happy."
All of the people in "advanced" nations that participated in the study exhibited this U-shaped trend, Blanchflower said. According to the study, happiness reached its lowest point for men in the United States at 50 years of age and for women in the United States when they are in their mid-30s.
This pattern was less evident in developing states, due to factors such as the shorter average life spans of residents in less industrialized countries.
Blanchflower said he believes this U-shaped pattern exists because people in their mid-40s begin to realize that certain goals have become unattainable and must "quell their infeasible aspirations," though he lacks concrete evidence to support his theory.
"When you're young you can allocate your time pretty freely," Blanchflower said, offering an explanation as to why people realize they are unable to achieve their goals as they age.
After this slump, if people are in good health, their happiness returns to its former high levels as they begin to accept that many of their former ambitions are unrealistic, Blanchflower said.
Not everyone agrees with Blanchflower's findings. Ed Deiner, a professor of psychology at the University of Illinois at Urbana-Champaign, who studied happiness for 30 years, said more evidence is needed to prove a direct correlation between age and unhappiness, USA Today reported. According to Deiner, proving that there is no correlation between other factors and levels of happiness is insufficient. Angus Deaton, a professor of international affairs and economics at Princeton University, said the U-shape is not a general trend because his own studies have indicated that in certain countries, older people are less happy than younger, according to USA Today.
Blanchflower acknowledged that not all people in their mid-40s say they are unhappy, but says his conclusions are based on the experience of hundreds of thousands of people.
"They have no idea how happy they'll be in the future, nor do they have any idea about how happy people are who are one year older than they," he said. "If you want to believe an anecdote, that's up to you. This is science."
Blanchflower has been compiling information on happiness for the last decade.
"We all should be interested in the pursuit of happiness," he said.
