On suicide and self-harm in university students and outcomes in persons with bipolar disorder and their offspring

Suicide is one of the leading causes of death in young persons in Sweden and globally. The last decades have seen an increasing proportion of the youth population engaging in university level education. The university period usually coincides with other important life events such as moving away from home. Early adulthood is furthermore a period when severe mental disorders, such as bipolar disorder and schizophrenia, may become symptomatic.

Bipolar disorder is highly heritable, with genetics accounting for approximately 60-80% of the risk. The disorder is often diagnosed with many years of delay, partly due to its episodic features. More than one third of all people with bipolar disorder have university level education and more than half hold an occupation. Suicide risk varies between people working in different occupations. Healthcare professionals, especially nurses, have a higher suicide risk, but there is a knowledge gap concerning whether there could be a selection of individuals with mental health vulnerability and vulnerability to suicide into these occupations. There is also a need for more knowledge concerning suicide risk and risk of other outcomes in people with bipolar disorder and in their children to better inform prevention strategies.

In Study I, we explored the risk of suicide and other mortality during ongoing university studies compared with periods of not studying at university. The nonstudy time periods were stratified by attained educational level. We found that having ongoing university studies was associated with a twofold risk of suicide compared to periods of non-studies when having attained at least one semester of university education. Having attained the lowest level of education was, however, associated with the highest risk of suicide and other mortality.

In Study II, we went on to investigate whether certain university program categories were associated with a higher risk of suicide and self-harm. We were particularly interested in whether the association previously found between suicide risk and working as a nurse or a physician could be mirrored among students aiming for these occupations. We found that being a nursing student, but not a medical student, was associated with a higher risk of suicide and of self-harm within the first three years after starting university studies.

In Study III, we examined a broad range of consequences, including suicide, selfharm, and low school grades, from birth to age 18 in offspring of one or two parents with bipolar disorder. We found that having a parent with bipolar disorder was associated with a more than tenfold risk of a bipolar disorder diagnosis, and with a higher risk of other psychiatric conditions as well as of some somatic conditions, low school grades, accidents, criminal behavior, selfharm, and suicide compared with not having a parent with bipolar disorder.

In Study IV, we explored associations between having bipolar disorder and somatic conditions, accidents, injuries, victimization, and self-harm. We found that bipolar disorder was associated with an increased risk of cardiovascular, neurological, and other somatic conditions, with a threefold increased risk for sleep disorders, dementias, fibromyalgia, and restless leg syndrome compared with the general population. Risk of self-harm was increased more than sevenfold and similarly elevated regardless of sex or bipolar disorder subtype.

In conclusion, this thesis shows that ongoing university studies can be a risk period for suicide and that there may be a selection of individuals with increased vulnerability to suicide into nursing education programs. Moreover, we show that offspring of parents with bipolar disorder are vulnerable to multiple psychiatric conditions, and adverse social outcomes during childhood and adolescence. Lastly, in people with bipolar disorder there is a higher risk of several somatic disorders, accidents, injuries, and self-harm compared with in people without bipolar disorder. Taken together our findings suggest that targeted support for the subgroups identified here as vulnerable to suicide or to multiple difficulties during childhood and adolescence could help decrease their risk of adversity, including suicide. Also, persons with bipolar disorder who have medical comorbidities may benefit from increased collaborations between somatic and psychiatric specialties.

List of scientific papers

I. Lageborn CT, Ljung R, Vaez M, Dahlin M. Ongoing university studies and the risk of suicide: a register-based nationwide cohort study of 5 million young and middle-aged individuals in Sweden, 1993-2011. BMJ Open. 2017;7(3):e014264.
https://doi.org/10.1136/bmjopen-2016-014264

II. Lageborn CT, Bjureberg J, Song J, Runeson B, Möller J, Ljung R, Dahlin M. Risk of suicide and self-harm in university students entering different university programs - a national register-based cohort study in Sweden. Soc Psychiatry Psychiatr Epidemiol. 2023 Aug;58(8):1139-1149.
https://doi.org/10.1007/s00127-023-02484-2

III. Lageborn CT, Zhou M, Boman M, Sjölander A, Larsson H, D’Onofrio BM, Pettersson E, Lichtenstein P, Landén M. Childhood and adolescence outcomes in offspring to parents with bipolar disorder: The impact of parental comorbidity, parental sex, and bipolar subtype. [Submitted]

IV. Lageborn CT, Virtanen S, Sjölander A, Chang Z, Brikell I, Kuja-Halkola R, D'Onofrio BM, Garcia-Argibay M, Larsson H, Pettersson E, Lichtenstein P, Landén M. Somatic morbidity, accidents, injuries, and self-harm in bipolar disorder. [Manuscript]