Behind the Numbers - Longevity and Bipolar Disorder (part two)

The research is pretty conclusive: people with bipolar disorder die earlier than their peer group’s average. But the data leaves out a lot. It’s worth taking a peak behind the numbers.


In my previous post, Longevity and Bipolar Disorder, I cited two studies that investigated the link between bipolar disorder and shortened lifespan. The results were striking, concluding that those with bipolar disorder have a life expectancy 8 – 20 years shorter than they would have without the disorder.

Big decisions are made with this data. It affects treatment prognosis and protocols, and becomes part of actuarial tables used to make decisions on rates and availability of various types of insurance. The results also drive future research.

It makes sense to be critical in considering the results.

The first thing that jumps out is the significant difference found in longevity rates between the study in Denmark and the study in the UK. Subjects of the Danish study with bipolar disorder who are between the ages of 25 and 45 have a lifespan reduced by 8.3 – 12.0 years. The number of years for the British is 9 – 20.

What could reconcile such a big difference?

While it seems obvious to attack the research methods, we must note that both studies were performed by very well-regarded universities, and both were peer reviewed. I’m confident we can accept that the results are accurate for the populations surveyed.

So what could be different about the populations? Demographic and socio-economic factors can greatly influence outcomes, so a more diverse sample will lead to greater variance in the results. The availability and quality of the healthcare delivered to these populations will also have a huge impact on the longevity measured.

So much more goes into the results than just the fact that the people in the samples had bipolar disorder. Differences in income, ethnicity, lifestyle and levels of stress can weigh just as heavily on the data. And surely there are great differences between the UK and Northern Europe.

So what about the United States? The National Institutes of Health cites the Danish study in a search of their database, as no large-scale equivalent study appears to have been investigated using an exclusively US population. Would the even greater diversity found in the US yield very different results?

And what about access to and quality of healthcare? One of the probable causes of early morbidity listed in the Danish study is the fact that many people with mental illness don’t access healthcare effectively. In the United States we have the unique situation that, because of lack of insurance, a large number of people with mental illness not only cannot access healthcare effectively, they can’t access it at all. Here the quality of healthcare is excellent. But oftentimes, if you can’t afford it you can’t have it.

If the study were conducted in the United States would that make the numbers worse?

Also of note is that causes of death of the people in the study are lifestyle choices or diseases co-morbid with bipolar disorder. Given the whole mind-body experience, environmental threats, and predisposition to other illnesses, it’s impossible to say how much bipolar alone contributed to early death. Health is too interconnected and influenced by too many factors to come to that specific a result. But we do know that longevity is shortened in populations with bipolar disorder.

Finally, not cited in the studies is the influence of medication on longevity.  Certainly, in most cases, available medicine has lead to longer lives, or at least an increased quality of life. But unconsidered are medication noncompliance, side effects, or the effects of long-term use of efficacious, yet powerful, drugs.

So while the results of the studies are precise, there’s a lot the results can’t tell us. The researchers point out that lifestyle and stress greatly influence longevity in people with bipolar disorder. We can certainly focus on living healthy and managing stress.

The implication is that if you make positive lifestyle choices you're likely to live longer.

Perhaps then, those of us with bipolar disorder can improve our longevity.  Information can help, and I want to use the best of it I can find.  I have a great marriage (finally!) and a wonderful young daughter.  I surely don't want to die young.  So kudos to those of us who are getting older with bipolar.  May life be long and healthy.