Understanding the relationship between depression and trajectories of physical multimorbidity accrual: longitudinal analysis of UK Biobank data

University of Edinburgh

Lay summary

There are increasing numbers of people who have multimorbidity which means living with multiple physical and/or mental health conditions. Increasing multimorbidity has a number of causes. People are living longer and are more likely to survive life-threatening illness than in the past (for example, anyone who survives a heart attack will have to live with chronic heart disease).

The combination of physical conditions with depression is very common. About one in five people with a physical condition have depression, and this combination is associated with worse physical and mental health outcomes. It is therefore important to understand how physical conditions and depression are related. Existing research has often looked at people at one point in time. This means that it isn't possible to know if depression causes physical disease, or if physical disease causes depression, or both.

The aim of this research is to examine the relationship between physical conditions and depression. There are three stages to this work.

First, we will develop several ways of measuring the patterns of physical conditions that people get in middle and older age; for example, examining the rate at which people develop new conditions and identifying groups of conditions that develop together (such as different conditions caused by smoking). We will also explore different ways of measuring depression in the data.

Second, we will examine whether depression before the start of the study predicts how people develop physical conditions. We will carefully account for the effect of other individual characteristics which might be linked to both depression and patterns of physical conditions such as gender, smoking and obesity.

Third, we will examine whether different patterns of physical conditions predict whether people develop new or recurrent depression. Again, we will carefully account for the effect of other individual characteristics.