![2349145069_a24514602b_o](https://www.nationalelfservice.net/cms/wp-content/uploads/2016/12/2349145069_a24514602b_o-150x150.jpg)
Bipolar disorder is a mental illness characterised by swings from extremely high to extremely low moods. Experiencing these mood swings can be very debilitating, and many people with bipolar disorder are impaired in their day-to-day lives.
In the search for possible causes, researchers have examined the childhood experiences of people with bipolar disorder. There is evidence suggesting that people with bipolar disorder are more likely to have experienced adversity when they were young, such as abuse and neglect, compared to healthy adults. However, most of the studies are conducted in relatively small samples and the findings are not always consistent.
The aim of a recent study by Palmier-Claus and colleagues was to meta-analyse results from all studies examining rates of childhood adversity in bipolar disorder, to test whether there was an overall association between the two.
![Evidence suggests that neglect, abuse, bullying and the death of a parent may contribute to later bipolar disorder, but more reliable studies are required.](https://www.nationalelfservice.net/cms/wp-content/uploads/2016/12/6082137401_ac9bbe3a9a_b-300x225.jpg)
Evidence suggests that neglect, abuse, bullying and the death of a parent may contribute to later bipolar disorder, but more reliable studies are required.
Methods
The authors conducted a systematic review and meta-analysis. They began by searching the psychology and psychiatry literature for studies published between 1980 and 2014 that had bipolar disorder and childhood adversity as their topic. Studies had to be published in peer-reviewed, English-speaking journals.
This initial search yielded 5,395 studies. However, the number decreased as the authors applied stricter criteria. Studies had to be epidemiological or clinical case-control studies that compared rates of childhood adversity between two groups of individuals: those with a diagnosis of bipolar disorder and those without a diagnosis of bipolar disorder or related psychiatric problems, such as depression and schizophrenia.
Childhood adversity was defined as having experienced neglect, abuse, bullying or the death of a parent before age 19. The authors did not include spanking or shouting by caregivers as child adversity, because they assumed these practices to be subject to cultural variability. Childhood adversity did not include divorce, or growing up in difficult circumstances, such as in poverty.
Applying these inclusion criteria narrowed the number of studies down to 19 that were deemed eligible for analysis. The majority were clinical case-control studies, altogether comprising over a thousand individuals with a diagnosis of bipolar disorder, and a similar number of controls. Six studies were epidemiological studies, with altogether over 2 million participants. From these studies, the authors extracted the statistics needed to conduct a meta-analysis.
Results
There were four main results:
- Childhood adversity was overall more common in adults with a diagnosis of bipolar disorder, compared to those without
- Of the 19 studies, 15 found such a difference
- However, the size of the effect varied across studies, with some reporting larger differences than others
- The authors did not find evidence for publication bias, suggesting little selective publishing of studies.
- Adults with bipolar disorder had experienced higher rates of childhood adversity across all its forms, including physical and sexual abuse as well as physical and emotional neglect
- Associations were particularly high for emotional abuse
- The only non-significant difference between cases and controls was for parental loss.
- Rates of adversity did not differ among individuals with different types of bipolar disorder
- Bipolar disorder type I and type II are distinguished based on their symptoms: type I is characterised by periods of mania and type II by attenuated mania
- However, as the results show, even though individuals with different types have different symptoms, they are both at equally high risk of having experienced childhood adversity.
- People with bipolar disorder experienced similar rates of adversity as people with schizophrenia and depression, although the results of comparisons for the latter were more ambiguous
- This result suggests that rates of childhood adversity are elevated in several psychiatric problems; not just bipolar disorder.
![Overall, childhood adversity was more common in adults with a diagnosis of bipolar disorder, compared to those without.](https://www.nationalelfservice.net/cms/wp-content/uploads/2016/12/13924365194_de49fbfb5c_o-300x201.jpg)
Overall, childhood adversity was more common in adults with a diagnosis of bipolar disorder, compared to those without.
Strengths and limitations
This is a comprehensive study that did not only compare childhood adversity across people with bipolar disorder and controls, but also examined different types of childhood adversity and psychiatric problems. However, there are some limitations:
- A relatively large number of studies was excluded because of what the authors describe as “no valid assessment of bipolar disorder” or “no valid trauma assessment”. It would have been useful to have the characteristics of these excluded studies discussed in more detail, so that future meta-analyses are able to consider whether to broaden their exclusion criteria to include some of them
- Only studies with formal diagnoses of bipolar disorder were included, rather than symptoms or subthreshold disorder, which might have extended the evidence base
- No information was provided on the average age of individuals diagnosed with bipolar disorder. This would have been interesting, to evaluate how likely it may be that bipolar disorder predicted exposure to adversity rather than vice versa
- It was not possible to examine possible explanations for the sizeable variation of effect sizes across the studies.
Implications
This study contributes to a large body of evidence showing higher rates of childhood adversity in people with psychiatric problems. There are several interesting future questions that the findings of the study raise:
- Virtually all of the studies in the meta-analysis assessed childhood adversity retrospectively, i.e. by asking adults to recall their experiences during childhood. Such studies are prone to biases, for example if adults with bipolar disorder are better at remembering adversity. To test whether this affects the findings, more longitudinal studies are needed that assess adversity in children and then follow them up into adulthood, to examine whether they are more likely to develop bipolar disorder.
- Longitudinal study designs would also be helpful in establishing whether adversity is a risk factor for bipolar disorder. The findings of the meta-analysis show that there is a link between adversity and bipolar disorder, but not whether adversity causes disorder. It is possible that there are factors that make individuals more likely to experience adversity and to develop bipolar disorder, for example growing up in deprivation or having violent parents. More studies are needed to examine this possibility.
- Finally, it would be interesting to examine which specific symptoms adversity affects. For example, the meta-analysis showed that adversity was associated not only with bipolar disorder but also with schizophrenia and, to a lesser extent, depression. Thus, it is possible that adversity is linked with an individual’s general risk for psychopathology, rather than one specific problem per se. It is also possible that it is associated with psychotic symptoms more specifically, which occur in some individuals with severe bipolar disorder and depression, as well as in schizophrenia. Future studies will help answer these questions.
![This study further establishes the association between childhood adversity and bipolar disorder, but more work is needed to provide us with clinically useful evidence.](https://www.nationalelfservice.net/cms/wp-content/uploads/2016/12/4979030420_77b090328d_b-300x188.jpg)
This study further establishes the association between childhood adversity and bipolar disorder, but more work is needed to provide us with clinically useful evidence.
Links
Primary paper
Palmier-Claus JE. et al (2016) Relationship between childhood adversity and bipolar affective disorder: systematic review and meta-analysis. The British Journal of Psychiatry 1–6. doi: 10.1192/bjp.bp.115.179655 [BJPsych abstract]
Since twin studies have found that bipolar disorder and schizophrenia are highly heritable, it is also possible that childhood adversity is not causative but merely related to traumatizing behaviors by parents who also had bipolar disorder or schizophrenia.
The concept of heritability primarily applies to populations, not to individuals. It does not provide any direct evidence of genetic inheritance, and should not be taken as providing fundamental and reliable evidence of genetic inheritance. Therefore, it should not be taken as a given from which other conclusions are extrapolated.
Joseph, thank you for your comment. I discuss this point a little bit in the Implications, where I mention the possibility of third variables (which genetic influence would fall under) causing both child adversity and bipolar disorder. If you are interested in this topic, you might want to look for studies that take into account genetic influences; there are now some showing that childhood trauma appears to increase risk for future mental health problems even after accounting for genetic influences (here is a British study, looking at trauma and psychotic symptoms: http://ajp.psychiatryonline.org/doi/pdf/10.1176/appi.ajp.2010.10040567; here is another study: http://ajp.psychiatryonline.org/doi/pdf/10.1176/appi.ajp.2011.10101531). However, we certainly need more research to investigate what’s underlying the association between trauma and later mental health problems.
I agree that childhood trauma may contribute to psychotic illness, but also think it is overemphasized. Many of the abundant trauma studies that are so popular among today’s proponents of trauma-informed care barely mention the role of genetics. Yet, twin studies have found a relationship between genetic inheritance and psychotic disorders that is far stronger than the relationship between childhood trauma and psychosis. Specifically, an identical twin of a person with schizophrenia is almost 50 times as likely to develop the disorder as a member of the general population, even when they are raised apart. This makes the genetic risk about an order of magnitude higher than the trauma risk. The authors of the second study you shared omitted details about their methodology that makes it impossible for me to understand their findings. However, the risk of psychosis due to trauma they found after controlling for other variables appears to be about doubled in study groups with reasonable sample sizes. The first study you shared found higher odds ratios for victims of trauma, but also set a higher standard for maternal evidence of psychosis and thus may have inadvertently included those with a history of psychosis in the group thought to not have any such history. In any case, the odds ratios for these two studies are in the 1.5 to 5.0 range, consistent with other trauma studies, and less than one-tenth the shared risk of schizophrenia in genetically identical individuals. I think this is a good summary of the genetic risks: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2826121/
Respectfully, as the opening line of the following 2014 article indicates, I’m not sure that it is accurate to say that there is an “abundance” of studies on trauma and bipolar disorder – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4539529/ . Personally, I would take note of recognised trauma expert, psychiatrist Bessel van der Kolk, author of bestseller “The Body Keeps the Score”, who in 2015 created a 4-minute video with a self-explanatory title, “Psychiatry must stop ignoring trauma” – https://www.youtube.com/watch?v=HR22lvBo1rQ.
Also, I wouldn’t personally bet my house on twin study results. Twin studies do not provide any direct evidence of genetic abnormality, and they have many critics.
Joseph, thank you for your comment. I have studied genetic influences on mental health during my PhD, so am well aware of and agree with you on the importance of taking genetic influences into account. We certainly need more research to better understand genetic influences on psychosis. If you are interested in this topic, you might enjoy reading around the recent genomic research on schizophrenia and bipolar disorder if you haven’t done so already; there are exciting new discoveries nearly every day.
Coming back to this meta-analysis, I suppose what is important to remember is that findings of genetic influences on psychosis don’t mean that environmental influences aren’t also worth studying. The same twin studies that show genetic influences on psychosis also show that even genetically identical twins differ in whether they will develop psychosis, suggesting that there are environmental influences that, on their own or in interaction with genetic disposition, affect the risk for experiencing it. Childhood trauma may be one such influence.
Good posting, thank you.
For twenty years I worked with many people diagnosed with bipolar, and its association with woundedness, trauma (often, trauma with a small “t”), distress and defense mechanisms is, in my experience, very consistent and clear.
It is a great pity that this association does not receive anything like the attention it deserves within mainstream mental health services.
Good to see this article reviewed here.
Thank you, I’m glad you enjoyed it!
Interesting blog. Is there any mention that the adults experienced symptoms of a bipolar disorder in childhood and whether or not their disorder precipitated the adversity in any way?
Hi Mark, Thank you for your comment. As far as I remember, there was no mentioning of it, but it is an interesting possibility that I allude to briefly in my discussion of the findings. My guess is that this was not taken into account in the case-control or retrospective studies that this meta-analysis drew on, because a test of this possibility really requires a longitudinal study design (i.e. following people up from early childhood into adulthood).