Cause of death in people with bipolar disorder

Bipolar disorder (BD) also known as ‘bipolar affective disorder’, is a mental health condition associated with changes in mood (usually between depression and mania), with stable mood periods in between. It has a worldwide prevalence of 1.2% (Merikangas, 2009). The extreme fluctuations in mood that people with bipolar disorder experience, often make daily life functioning difficult.

Increased rates of death amongst individuals with bipolar can be partially explained by higher rates of physical illness (what’s referred to as the mortality gap), in particular, cardiovascular and metabolic diseases (Carvalho et al., 2024). Suicide is reported as the main cause of death among individuals with BD compared to the general population (Hayes et al., 2017) and owing to a higher risk of physical disease among people with BD, increased mortality rates from natural causes is observed (Biazus et al., 2023). 

Recent studies have sought to uncover the causes of mortality among individuals with bipolar disorder (BD). However, many of the specific factors leading to increased deaths amongst individuals remain unclear. Why is this study important? Paljärvi and colleagues (2023) aimed to understand why people with bipolar disorder between 15 and 64 years old are more likely to die compared to the general population, whilst also identifying the specific causes – both external and somatic.

Bipolar disorder has been linked with increased mortality, but the causes for excess death compared to the general population remain less known.

Methods

The researchers followed Finnish people aged 15 to 64, with and without a diagnosis of BD from 2004 until 2018 to monitor whether people with BD died more frequently and earlier than people without it, and to compare the causes of their deaths. They compared causes of death, looking at external (unnatural) causes (e.g., accident, suicides) and somatic (natural) causes (e.g., disease, health problems). 

Results

Overall, the study found that individuals with bipolar disorder had higher mortality rates compared to the general population, with external causes like accidents and suicides contributing significantly to this excess mortality, especially in younger age groups.

Strikingly, 64% of the deaths were ‘excess’, which means they exceeded the mortality rates of the general population. These excess deaths were therefore specifically linked to having bipolar disorder. 

Older individuals with BD (45-64 years) were particularly at risk of death compared to the general population by somatic causes. 

Overall, around 10 years of life were lost in those with BD compared to the general population.

To conclude, overall deaths were 3 times higher amongst those with BD. Deaths due to somatic causes were 2 times higher, and deaths due to external causes as much as 6 times higher! With that, suicide was the highest cause of increased deaths in people with BD, being 8 times higher.

The mortality gap between people with bipolar disorder and the general population can be attributed to external causes of death, such as suicide or accidents.

Conclusions

It’s clear that individuals with bipolar disorder face a higher risk of death from external factors (e.g., self-harm, accidents)- and not just physical illnesses. The younger folk, aged 15–44, were especially vulnerable to these non-physical causes. So, whilst heart health matters, we need to shift our focus from just physical health issues in BD, and think about external factors that might be linked with premature death, too.

The authors have indicated the important role of age in excess deaths of people with bipolar disorder, with younger people being particularly vulnerable.

Strengths and limitations

The research involved a large number of people with bipolar disorder. This means that it’s unlikely that the findings occurred just by chance, and probably reflect a genuine relationship between having bipolar and premature death. The researchers used multiple nationwide Finnish databases to identify people with bipolar disorder from across many different settings. This makes the sample more representative. In other words, the researchers were able to identify more people with bipolar disorder than if they had relied on hospital registers alone.

It’s important to acknowledge that the number of people who passed away might be higher than what’s officially reported. This could be because some individuals were never diagnosed with the condition, or they were mistakenly diagnosed with something else (e.g. unipolar depression). So, the actual impact of the situation could be more significant than what the numbers suggest. This is crucial because we’re aware that it takes about 7-10 years for someone to receive their first diagnosis of bipolar disorder. That’s a long time for someone to go without knowing they have this condition. 

It should be noted that the study was done in Finland, so we should be careful about directly applying its findings to other countries, including the UK. Finland has its unique factors, like culture and healthcare, which could make the results different elsewhere. We should ask ourselves, are the people in this study so different from people in our country that we cannot use these results in some way?

The number of people with bipolar disorder who faced premature mortality may be higher due to misdiagnosis or underdiagnosis.

Implications for practice

• This study highlights that in order to reduce excess mortality in individuals with BD, we need to use a range of strategies. The findings indicate that strategies should be tailored to reflect different causes of death for different age groups.
• Interventions aimed at preventing substance abuse are crucial for reducing excess mortality in bipolar disorder, particularly in older people.
• Clinicians need to consider and balance out how best to manage symptoms in bipolar disorder, and any potential long-term side effects of medications that could affect physical health.
• Suicide prevention should remain a priority, as this is the leading cause of death among individuals with bipolar disorder. Qualitative research can shed more light into the lived experience of suicidal ideation, intent and behaviour in this population, as well as helpful mechanisms and protective factors to increase resilience.

Suicidal ideation and behaviour needs to be better understood in people with bipolar disorder to identify more prevention strategies.

Statement of interests

No conflicts of interest to declare.

Contributors

Thanks to the UCL Mental Health MSc students who wrote this blog from Bass student group: Rianna Patterson, Katherine Ede, Tarini Sharma, Vanessa Eastick, Asha Mohanlal, Hemanshi Mehta, Yu Yue and Amber Jarvis.

UCL MSc in Mental Health Studies

This blog has been written by a group of students on the Clinical Mental Health Sciences MSc at University College London. A full list of blogs by UCL MSc students can be found here, and you can follow the Mental Health Studies MSc team on Twitter.

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Links

Primary paper

Paljärvi T, Herttua K, Taipale H, Lähteenvuo M, Tanskanen A, Fazel S, Tiihonen J. Cause-specific excess mortality after first diagnosis of bipolar disorder: population-based cohort study. BMJ Ment Health. 2023 May;26(1):e300700. doi: 10.1136/bmjment-2023-300700.

Other references

Biazus, T., Beraldi, G., Tokeshi, L. Rotenberg, L., Dragitoti, E., Carvalho, A., Solmi, M. Lafer, B. (2023). All-cause and cause-specific mortality among people with bipolar disorder: a large-scale systematic review and meta-analysis. Mol Psychiatry 28, 2508–2524. https://doi.org/10.1038/s41380-023-02109-9

Carvalho, A., Hsu, C., Vieta, E., Solmi, M., Marx, W., Berk, M.,Liang, C., Tseng, P., Wang, L. (2024). Mortality and Lithium-Protective Effects after First-Episode Mania Diagnosis in Bipolar Disorder: A Nationwide Retrospective Cohort Study in Taiwan. Psychother Psychosom. https://doi.org/10.1159/000535777

Chan, J. K. N., Wong, C. S. M., Yung, N. C. L., Chen, E. Y. H., & Chang, W. C. (2021). Excess mortality and life-years lost in people with bipolar disorder: an 11-year population-based cohort study. Epidemiology and psychiatric sciences, 30, e39. https://doi.org/10.1017/S2045796021000305 

Hayes, J. F., Marston, L., Walters, K., King, M. B., & Osborn, D. P. J. (2017). Mortality gap for people with bipolar disorder and schizophrenia: UK-based cohort study 2000-2014. The British journal of psychiatry :the journal of mental science, 211(3), 175–181. https://doi.org/10.1192/bjp.bp.117.202606

Merikangas, K. R., & Pato, M. (2009). Recent developments in the epidemiology of bipolar disorder in adults and children: Magnitude, correlates, and future directions. Clinical Psychology: Science and Practice, 16(2), 121–133. https://doi.org/10.1111/j.1468-2850.2009.01152.x