"It's true! Optimists do live longer," is the slightly misleading headline from the Mail Online.
The study it reports on actually looked at the effects of optimism on physical and emotional health in 369 people recovering from a heart attack or unstable angina (angina that does not respond to medication), rather than overall lifespan.
The participants were assessed for their level of optimism, depressive symptoms and physical health. They had a repeat assessment after 12 months.
The study also looked at whether participants were likely to have a major cardiac event (such as a heart attack or stroke) in the next 46 months.
Optimism alone did not have an effect on whether people had another major cardiac event, but a significant effect was seen when they looked at levels of optimism and symptoms of depression.
People who were both optimistic and free of depression had half the risk of having a major cardiac event compared to people with low optimism and some symptoms of depression.
This effect could be due to issues of compliance. People who feel they have something to live for are probably more likely to carry out recommended lifestyle changes, such as quitting smoking, as was seen in this study.
The researchers now hope to find ways to improve the optimism of people at risk of heart attacks.
Where did the story come from?
The study was carried out by researchers from University College London, the National University of Ireland, the Karolinska Institute in Stockholm and the University of London. It was funded by the British Heart Foundation.
The study was published in the peer-reviewed medical journal Psychosomatic Medicine and is available on an open-access basis so it is free to read online.
The Mail Online and the Daily Express’s reporting were accurate but both of their headlines were potentially misleading. The Mail’s “Optimists live longer” is unsupported as the study did not measure the difference in life expectancy between pessimists and optimists.
While the Daily Express’s headline "Keep positive to live longer: It cuts risk of heart attack by half, say experts" fails to make clear that this study was in people recovering from a heart attack or unstable angina.
The Mail did include an important quote from Dr Mike Knapton, associate medical director at the British Heart Foundation, who said: "The next steps for this research would be to show psychotherapy like cognitive behavioural therapy to improve optimism can improve the outcomes for pessimistic people."
What kind of research was this?
This was a cohort study that aimed to assess the impact of optimism on recovery after having an acute coronary syndrome (ACS). This term includes heart attacks and unstable angina. As optimism influences a person’s behaviour, the researchers wanted to see what effect this had on physical health, risk of having a further major cardiac event and depressive symptoms. As this was a cohort study it cannot prove that optimism alone directly causes better outcomes, as many other factors may be involved in the link.
What did the research involve?
Researchers assessed the level of optimism in 369 people after an ACS, then grouped them into low, medium and high categories and compared their health outcomes after 12 months. They also analysed their medical records for an average of 46 months.
The data analysed came from two prospective studies carried out at St George’s Hospital in London. People were invited to participate if they had suffered from an ACS between December 2001 and August 2004 and again from June 2007 to September 2008. The first study group was interviewed in hospital and completed questionnaires a week to 10 days after the ACS. The second group were assessed at home on average 21 days after the ACS.
A follow-up assessment was made by telephone and questionnaires 12 months later to measure physical health status, depressive symptoms, smoking, physical activity, and fruit and vegetable consumption. Hospital medical records were used over the next 46 months on average to determine if they had any further major cardiac event, including death due to cardiovascular disease, heart attack or unstable angina.
People were eligible for the study if they were over the age of 18 and did not have another condition that could affect symptom presentation or mood (giving examples such as cancer or unexplained anaemia).
Optimism was assessed using a revised version of the "Life Orientation Test". In this test, the person is asked to rate how strongly they agree or disagree with statements such as "in uncertain times, I usually expect the best".
Depressive symptoms were assessed using the standardised Beck Depression Inventory. This provides a score of between 0 and 63:
- scores of up to 10 are considered to be normal
- 11 to 16 mild mood disturbance
- 17 to 20 borderline clinical depression
- 21 to 30 moderate depression
- 31 to 40 severe depression
- over 40 extreme depression
In this study, the researchers used a cut-off of 10 or more to indicate clinically significant depressive symptoms.
Physical health status was assessed using the physical health section of the 12-Item Short Form Health Survey (SF-12). This is measured on a scale of 0 to 100, higher scores indicating better health. This includes factors such as limited physical function, effective role fulfilment and pain.
The data was analysed adjusting for age, sex, ethnicity, socioeconomic status, history of depression and Global Registry of Acute Coronary Events (GRACE) risk score, which is a measure of the clinical risk of having a further cardiac event.
What were the basic results?
Further major cardiac event
After adjusting for the confounding factors, optimism alone was not significantly associated with further risk of a major cardiac event. When combining people with low optimism and clinically significant depressive symptoms, they were more than twice as likely to have a further cardiac event compared to people with high optimism and low depressive symptoms (odds ratio (OR) 2.56, 95% confidence interval (CI) 1.16 to 5.67).
After 12 months, optimistic people were 18% less likely to have depressive symptoms (OR 0.82, 95% CI 0.74 to 0.90).
Optimism was not related to physical health status score immediately after ACS, but higher scores were found after 12 months. People classed as having low or medium optimism had scores of 50 on the SF-12, whereas people with high optimism scored 54.6 (range 0 to 100).
After 12 months, 47.9% of people with low optimism were still smoking compared to 15.3% of people with high optimism.
Fruit and vegetable intake
Twice as many highly optimistic people were eating five or more fruit and vegetables at 12 months compared to people with low optimism (40% compared to 20%).
There was no difference between optimism and changes in physical activity.
How did the researchers interpret the results?
The researchers concluded that "optimism predicts better physical and emotional health after ACS" and that "measuring optimism may help identify individuals at risk". They believe that "pessimistic outlooks can be modified, potentially leading to improved recovery after major cardiac events".
This well-designed study found that people who have a higher level of optimism are less likely to smoke or have depressive symptoms, more likely to be eating five portions of fruit and vegetables a day, and have a slightly higher physical health score. It also found that people who have low optimism and depressive symptoms are more than twice as likely to have a major cardiac event than people with high optimism and no depressive symptoms.
In many ways the overall findings that a greater sense of wellbeing could be transferred into positive lifestyle changes, which could be linked to lower risk of subsequent heart effects, seem plausible. The researchers took into account various confounding factors that could be influencing the link, such as level of physical illness after the first ACS and history of depression.
However, a variety of things could influence how positive, or not, a person feels after a heart attack. Though the study attempted to exclude certain conditions that may have influenced mood and symptoms, it is unclear whether the study will have been able to capture an overall picture of the person’s starting health and functional status.
Other unmeasured things that can have an important influence on sense of wellbeing and recovery after serious illness include interpersonal relationships and the support of partners, family and friends. For example, consider an isolated person living alone to a person living with (an)others and with a wide and active social network.
Overall despite the researchers' best attempt to reduce the likelihood of confounding, it is still possible that other factors are involved in the complex link between optimism and future cardiac events.
There may also be some bias towards more optimistic people taking part in the study as it relied on patients agreeing to be interviewed and fill out questionnaires. It is possible that people with very low optimism may have refused to participate as there would be "no point".
The researchers now hope to find ways to improve the optimism of people at risk of heart attacks.
People with a reason to live are probably more likely to take steps to live longer. Read more advice about how to be happier.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.
Links To The Headlines
It's true! Optimists DO live longer: Having a positive attitude lowers the risk of a heart attack. Mail Online, March 5 2015
Keep positive to live longer: It cuts risk of heart attack by half, say experts. Daily Express, March 6 2015
Links To Science
Ronaldson A, Molloy G, Wikman A, et al. Optimism and Recovery After Acute Coronary Syndrome: A Clinical Cohort Study. Psychosomatic Medicine. Published online March 3 2015