CU Medicine identifies the road map of emergence of circadian dysfunction and psychopathologies in the offspring of parents with bipolar disorder in the Greater Bay Area

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25 Jul 2024

CU Medicine identifies the road map of emergence of circadian dysfunction and psychopathologies in the offspring of parents with bipolar disorder in the Greater Bay Area

Bipolar affective disorder is a severe mental disorder, characterised by recurrent manic/hypomanic and depressive episodes, and affects 1% to 4% of the population worldwide. Its heritability may reach over 80% and the common age of onset is about 20 years old. The Chinese University of Hong Kong (CUHK)'s Faculty of Medicine (CU Medicine) led a study, collaborating with 10 Greater Bay Area (GBA) hospitals, which has identified the progressive road map of psychopathological staging in the offspring of parents with bipolar disorder in the GBA, paving the way for early intervention and prevention. This is the first case-control study of the offspring of parents with and without bipolar disorder, encompassing the most comprehensive data from Asia to date, with a thorough evaluation of various symptoms and sleep disturbances. Study details have been published in General Psychiatry.

The offspring of parents with bipolar disorder may be at higher risk of developing this mental disorder and related conditions. Early intervention is crucial for prevention. Studying the evolution of mood, sleep features and other psychopathologies in high-risk offspring helps identify prodromal markers, risk factors and early psychopathologies for bipolar disorder, and offers direction for early intervention.

Delayed sleep phase symptoms and social anxiety in adolescents could be early signs of bipolar disorder

The study found that the offspring of bipolar patients had a twofold higher risk of behavioural symptoms in childhood than their age-matched controls. As these children entered their teenage years, they had a fourfold higher risk of circadian dysfunction, especially delayed sleep phase symptoms, with prominent delays in their circadian rhythm and a tendency to stay up late at night and sleep late, as well as a 7.5-fold higher risk of social anxiety symptoms and disorder. These findings helped the research team understand the road map of psychopathological changes in high-risk individuals before their conditions develop into full-blown clinical bipolar disorder.

First author of the study Dr Lei Binbin, Postdoctoral Fellow (honorary) from the Department of Psychiatry at CU Medicine, stated, "In this study, we identified several clinical markers, including the delayed sleep phase problems, that were reported as the early core manifestations of bipolar disorder. The findings enhanced our understanding of the preclinical staging model of bipolar disorder, which allows different early clinical intervention and prevention strategies to be developed."

Another study by the team shows dysregulation of melatonin secretion in the high-risk group

Another study conducted by the research team and published in the Journal of Affective Disorders in 2022 found that offspring of bipolar disorder patients had significantly lower melatonin[1] levels at night than controls. This may be explained by their increased sensitivity to melatonin suppression from environmental light exposure at night. Provided that melatonin is a kind of hormone that helps with sleep and regulates sleep-wake cycle, children of parents with bipolar disorder who have lower melatonin levels may therefore result in a disrupted circadian rhythm.

First author of this study Dr Feng Hongliang, PhD Graduate in CU Medicine's Department of Psychiatry, commented, "Light plays a crucial role in regulating circadian rhythm. Light pollution and the excessive use of electronic device use associate with sleep and circadian problems and poor mental health. Thus, raising awareness of the appropriate use of electronic device and create an appropriate sleep environment are essential, especially among high-risk adolescents with family history of bipolar disorder. Hopefully, this will reduce the impact on their melatonin secretion and circadian disruption, and prevent them from developing bipolar disorder."

Addressing bipolar disorder risk to promote mental health development

Professor Wing Yun-kwok, Choh-Ming Li Professor of Psychiatry and Chairman at CU Medicine's Department of Psychiatry, concluded, "Three-quarters of mental illness cases emerge before the age of 24. Early non-pharmacological interventions during adolescence, before the condition has fully developed, hold promise for reducing the risk of serious mood disorders. Appropriate strategies are required, such as maintaining regular sleep-wake routines, avoiding electronic devices before bedtime to improve sleep hygiene, potential cognitive and behavioural intervention for anxiety and mood symptoms and disorders, as well as seeking help early and receiving family support, especially during the critical period of adolescence. We hope this research will encourage patients' families, schools, communities, and policymakers to better understand bipolar disorder and its risk factors. Subsequently, better strategies can be formulated to prevent high-risk individuals from developing this mood disorder. Furthermore, collaborating with our research partners in the GBA enables us to jointly develop strategies for promoting mental health among the populations in the Area."

[1] A naturally occurring hormone in the body that promotes sleep.

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