B4393 - Examining causal bidirectional relationships between mental health and urinary incontinence in women - 21/08/2023

B number: 
Principal applicant name: 
Kimberley Burrows | Bristol Medical School (PHS) (United Kingdom)
Professor Carol Joinson, Ms Rochelle Knight
Title of project: 
Examining causal bidirectional relationships between mental health and urinary incontinence in women.
Proposal summary: 

Urinary incontinence (UI), defined as the complaint of any involuntary leakage of urine is a highly prevalent condition that can have adverse consequences for emotional well-being and quality of life in addition to being of economic importance to health services.
The cause of UI is not completely understood and includes psychological and physiological factors outside the lower urinary tract. The hypersensitivity of the bladder in urinary incontinence has guided researchers to consider psychological factors including anxiety and depression that may be of importance.
The comorbidity between UI and affective disorders including anxiety and depression is well established, but the precise nature of this relationship is unknown. Much of the existing research examining the relationship between UI and anxiety/depression is cross-sectional and is therefore unable to disentangle the temporal relationship between whether poor mental health is a cause or a consequence of UI.
The use of bidirectional MR can help to differentiate causality from correlation by testing the causal effects independently in each direction using single nucleotide polymorphisms (SNPs) found to be robustly associated with each trait in different genome-wide association studies (GWAS).  We will use GWAS summary statistics in a two-sample MR analysis to examine bidirectional causal relationships between anxiety/depression/neuroticism and UI in females. Two subtypes of UI will be explored. Stress urinary incontinence (SUI) is defined as a loss of urine associated with physical exertion, coughing or sneezing whilst urgency urinary incontinence (UUI) is loss of urine associated with a sudden compelling need (an urgency) to void.

Impact of research: 
If causal relationships (unidirectional or bidirectional) exist between anxiety/depression/neuroticism and UI, this could justify changes in the treatment of patients with incontinence and inform the development of new interventions.
Date proposal received: 
Tuesday, 8 August, 2023
Date proposal approved: 
Monday, 14 August, 2023
Genetic epidemiology (including association studies and mendelian randomisation), Incontinence, Mental health, 2-sample MR, Mendelian randomisation