Environmental

Various environmental risk factors have been associated with increased risk of bipolar disorder. However, the strength of associations are largely unknown, and the interaction effects between genetic and environmental factors, and among environmental factors themselves, vary from person to person.

Adult life events

What are adult life events? Life events that occur during adulthood are defined as particularly significant experiences that result in substantial changes to personal circumstances. These changes may be positive or they may be negative changes and can occur across all aspects of life, including health, education, employment, relationships, bereavement, housing, legal, and financial issues. What is the evidence for adult life events? Moderate to high quality evidence suggests no differences in the number of stressful events experienced prior to onset of bipolar disorder compared to unipolar depression or people without a mental illness. April 2019

Childbirth

We have not found any systematic reviews on this topic that meet the Library’s inclusion criteria. Pending enough primary studies, we invite reviews on this topic to be conducted. Alternatively we will endeavour to conduct our own review to fill this gap in the Library. April 2019

Childhood adversity

What are childhood adversities? Childhood adversities encompass a range of childhood experiences, including loss of a close relative, bullying, physical abuse, sexual abuse, emotional abuse, and neglect. The nature, timing, severity, and duration of exposure are likely to influence mental health outcomes. What is the evidence for childhood adversities in people with bipolar disorder? Moderate quality evidence suggests a medium-sized effect of higher rates of childhood adversity in people with bipolar disorder compared to controls, and a small effect when compared to people with major depression. No differences in rates of childhood adversities were found between people with bipolar disorder…

Environmental toxins

We have not found any systematic reviews on this topic that meet the Library’s inclusion criteria. Pending enough primary studies, we invite reviews on this topic to be conducted. Alternatively we will endeavour to conduct our own review to fill this gap in the Library. April 2019

Ethnicity

How is ethnicity related to risk for bipolar disorder? Some ethnic groups may show greater or less risk for bipolar disorder than others. Incidence refers to how many new cases there are per population in a specified time period, while prevalence refers to how many existing cases there are at a particular point in time. Differences in the incidence and prevalence across various ethnic groups can provide clues to possible causes of bipolar disorder. What is the evidence for ethnicity and risk for bipolar disorder? Moderate to low quality evidence suggests a small increased risk of bipolar disorder in people…

Familial factors

What is familial risk? Many disorders are the result of interaction between susceptibility genes and environmental influences. One example is cardiovascular disease; people with a family history of cardiovascular disease are more susceptible to heart problems, and environmental influences, such as diet, can increase this risk. Bipolar disorder is also a complex disorder that can arise from both genetic and environmental influences. What is the evidence for familial risk? Moderate to low quality evidence suggests a medium-sized increased risk of bipolar disorder in the offspring of people with bipolar disorder. There were also small effects of increased risk of depressive,…

Infectious agents

How are infectious agents related to risk for bipolar disorder? Exposure to infection is often cited as a risk factor for schizophrenia, and has recently been investigated in bipolar disorder. This topic summarises the available evidence for the risk of developing bipolar disorder following exposure to influenza and other infectious agents, both before and after birth. The physiological mechanisms of any association of these infectious agents with bipolar disorder are largely unclear. Please also see the topic in Physical Features on markers for infectious agents in adults with bipolar disorder. What is the evidence for infectious agents as risk factors…

Maternal diet during pregnancy

How is maternal diet during pregnancy related to risk for bipolar disorder? Consumption of a balanced diet during pregnancy aids the development of a healthy fetus which may act as a preventative factor for the development of bipolar disorder in adulthood. In contrast, consumption of substances or poor diet during pregnancy can be harmful to the developing fetus. What is the evidence for maternal diet during pregnancy? Moderate to low quality evidence suggests a medium-sized effect of increased risk of bipolar disorder in offspring of mothers who smoked during pregnancy. There were no associations between alcohol or caffeine use during…

Maternal illness during pregnancy

How is maternal illness during pregnancy related to risk for bipolar disorder? Maternal illness during pregnancy, particularly involving infectious agents has been associated with brain and behavioural abnormalities in the offspring, and so have been investigated as possible risk factors for bipolar disorder. What is the evidence for maternal illness during pregnancy as a risk factor for bipolar disorder? Moderate to low quality evidence suggests a medium to large effect of increased risk of bipolar disorder after exposure to maternal influenza during pregnancy, although when the trimesters were analysed separately, the effect remained significant only in the third trimester, and…

Migration

How is migrant status related to bipolar disorder? The term “migrant” usually refers to first generation migrants – people with a foreign birth place, and studies have assessed whether migration is related to risk of bipolar disorder. Any association observed between migrant status and increased risk of mental disorders has stimulated a great deal of explanatory hypotheses, including additional stress relating to migration and settling into a new country, and possible issues with discrimination. Other explanations include a tendency for at-risk individuals to migrate, and underlying genetic variances across cultures. What is the evidence for migrant status as a risk…

Obstetric complications

How are obstetric complications related to risk of bipolar disorder? Obstetric complications are a broad class of deviations from a normal course of events experienced during pregnancy, labour, delivery and the early neonatal period. Studies have attempted to investigate whether any deviation or combination of deviations are related to the subsequent development of bipolar disorder. Teasing out possible effects of obstetric complications is not simple because many other, and often unknown, contributing factors are most probably involved. What is the evidence for obstetric complications as risk factors for bipolar disorder? Moderate to low quality evidence suggests a large effect of…

Parental age

How is parental age related to bipolar disorder? There have been claims that advanced parental age may be a risk factor for the development of mental disorders in the offspring. Commonly offered explanations have been the occurrence of germline mutations in older adults and/or psychological factors such as earlier than normal parental death experienced at a vulnerable age. Pinpointing the age at which parenthood may be associated with a significantly higher risk of bipolar disorder could be useful knowledge for potential parents, particularly if there is a pre-existing increased genetic risk of developing the disorder. What is the evidence regarding…

Parental education

How is parental education related to bipolar disorder? Any association of low parental education with a higher risk for bipolar disorder has been largely inconsistent. This topic outlines the evidence for low parental education as a risk factor for bipolar disorder, however the results may reflect the effects of other influencing factors rather than parental education itself. What is the evidence for parental education as a risk factor for bipolar disorder? Moderate quality evidence suggests no differences in maternal education between people with bipolar disorder and people without bipolar disorder. No reviews assessed paternal education. April 2019

Parental psychological factors

How do parental psychological factors relate to risk for bipolar disorder? Exposure to parental psychological factors in utero and after birth may be linked to risk of bipolar disorder in the offspring. However, studies investigating the relationship between parental psychological factors and bipolar disorder have yielded inconsistent findings. What is the evidence for parental psychological factors during pregnancy? Moderate to low quality evidence suggests an increased risk of bipolar disorder in the offspring of mothers who were exposed to war stress during pregnancy. There was no association with exposure to maternal bereavement stress in utero. April 2019

Sibship

What is sibship? Sibship is a medical term meaning a group of individuals born of the same parents. Factors associated with sibship include birth order, number of siblings or number of births in the family, and inter-birth interval periods. It is not known how these factors may be associated with risk for bipolar disorder. What is the evidence for sibship as a risk factor for bipolar disorder? Moderate to low quality evidence suggests no association between twin birth and bipolar disorder in adulthood. April 2019

Socioeconomic status

We have not found any systematic reviews on this topic that meet the Library’s inclusion criteria. Pending enough primary studies, we invite reviews on this topic to be conducted. Alternatively we will endeavour to conduct our own review to fill this gap in the Library. April 2019

Substance use

How is substance use related to bipolar disorder? Various lines of evidence suggest an association between substance use and psychiatric disorders. In particular, substance use during adolescence or early adult life is now thought to be one of a number of environmental stressors that interact with genetic factors to predispose an individual to later bipolar disorder. What is the evidence for substance use as a risk factor for bipolar disorder? Moderate quality evidence suggests a medium to large effect of increased risk of bipolar disorder with prior cannabis use, and a small to medium-sized effect of increased risk of bipolar…

Traumatic brain injury

How is traumatic brain injury related to bipolar disorder? It is well established that traumatic brain injury increases the risk for a wide range of neuropsychiatric disturbances, however there is little consensus on whether it is a risk factor for bipolar disorder. What is the evidence for traumatic brain injury as a risk factor for bipolar disorder? Moderate quality evidence suggests a small effect of increased risk of bipolar disorder in people with a prior traumatic brain injury. April 2019

Urbanicity

How is urbanicity related to bipolar disorder? There is evidence that urban settings are associated with higher rates of some psychiatric disorders. Studies of urbanicity have defined exposure to urban environs in various ways, either consisting of urban-rural comparisons or defined according to population density which can include mixed urban-suburban-rural areas. The majority define urbanicity by degrees of population density, defined either as population per square kilometer or as the number of inhabitants within a defined location (e.g., capital, city, or town). It is not clear whether urban living is itself associated with a higher risk for bipolar disorder, as…

Winter birth

How is winter birth related to risk for bipolar disorder? Researchers have observed the existence of high and low prevalence (total number of cases) and incidence (number of new cases during a specified time frame) pockets for some psychiatric disorders, with rates varying depending on season of birth. These may be related to variances in temperature, precipitation, and sun exposure, however the underlying mechanisms involved are largely unknown. What is the evidence regarding winter birth as a risk factor for bipolar disorder? Moderate to low quality evidence suggests there may a greater risk of affective psychoses in people who were…

NeuRA Libraries

Title Colour Legend:
Green - Topic summary is available.
Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.