The current study aims to understand why some people with depression respond to treatment and others do not, using markers of clinical symptoms, both clinician reported outcome measures and patient reported outcome measures, demographic information, cognitive function, genetic sequence information (genomic), chemical measures of metabolism (metabolomic), protein makeup (proteomic) and the body's natural defence system (immune/inflammatory markers) together with collections of cells that will facilitate new research to drive improvements in diagnosis and treatment of mood disorders that may be proving difficult to treat. This will allow future clinical trials within the NHS, academia and industry to drive forward new approaches and treatments.

Participants who provide consent for re-contact for future treatment trials and other research studies have the potential to benefit from this with participation in experimental studies and clinical trials associated with improved patient outcomes. Overall, the cohort will generally support greater access to research opportunities for a wider population of people.

Inclusion Criteria:

• Those aged 18 and above
• Primary clinical diagnosis of MDD or bipolar disorder based on DSM-5/ICD-11 diagnostic criteria
• Participant is willing and able to give informed consent for participation in the study
• Possesses sufficient command of the English language required to complete study requirements, as assessed by the study team

Exclusion Criteria:

• Inability to complete study activities as assessed by the study team
• Presentation requires immediate emergency treatment
• Presentation requires clinical input not available within the research clinic

The current study aims to recruit adults aged 18 and over, currently residing in the UK with a diagnosis of major depressive disorder or bipolar disorder. The study will be advertised on social media and will allow people to self-refer to the study. We will also recruit via GP mail outs.