What Is Depression? Depression can be generally defined as a state of reduced or low mood. Depression has the potential to affect many aspects of a person’s life: their thinking (cognitions), their emotions, their behaviour, their mental and physical health, and their relationships. How Is Depression Diagnosed? It is important to note that depression is not always classified as a disorder. Common life events (such as redundancy, bereavement, some types of illness, etc.) have the potential to promote depressive symptoms, but these are likely to pass after the resolution of the life event/illness. However, depression can become a more severe and chronic disorder, leading to the individual being diagnosed as having Major Depressive Disorder. The fourth (current) edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) defines a Major Depressive Episode as involving at least five of the following symptoms during the same two-week period (the asterisked items must be observed): 1.Depressed mood.* 2.Diminished interest/pleasure in daily activites.* 3.Significant weight change/appetite change. 4.Insomnia/over-sleeping. 5.Restlessness/being slowed down. 6.Lack of energy. 7.Feelings or worthlessness/guilt. 8.Problems concentrating. 9.Recurrent thoughts of death/suicide. The presence of two or more Major Depressive Episodes (with at least a two- month gap between episodes) is defined as Major Depressive Disorder. How Common Is Depression? Research carried out by the Royal College of Psychiatrists suggests that depression is a very prevalent disorder: around one in five adults will experience depression at some point in their lifetime. Our Measure of Depression: The Major Depression Inventory (MDI) Why Are We Measuring Depression In Our Study? Depression is one of the most important measures in our study: we intend to investigate the effect of group identification on depression levels over time, using a longitudinal study design. There are a number of reasons why depression is such a key measure in our project. First, it is a commonly-used and easily-understood indicator of general mental health. Second, evidence from non-longitudinal studies (e.g., Sani et al., 2010; Sani et al., 2012) shows that the more participants identify with the social groups to which they belong (e.g., the family), the lower their levels of depression tend to be. Third, depression is a major source of personal distress and lost working hours in modern societies, so examining potential causes and treatments for depression is a worthwhile pursuit. How Are We Measuring Depression In Our Study? We are using the Major Depression Inventory (MDI) to measure depression in our study (Bech, 1998; Bech et al., 2001). This is a twelve-item inventory, which covers all the main areas outlined in the DSM-IV definition of a Major Depressive Episode. Participants are asked to indicate the extent to which they have experienced each of the following twelve symptoms during the past two weeks, using a 0 (at no time) to 5 (all of the time) scale. The higher score out of items 8 and 9 is retained, while the lower-scored item is deleted. The same occurs for items 11 and 12. This leads to a scale consisting of ten items. 1.Felt low in spirits or sad. 2.Lost interest in your daily activities. 3.Felt lacking in energy and strength. 4.Felt less self-confident. 5.Had a bad conscience or feelings of guilt. 6.Felt that life wasn’t worth living. 7.Had difficulty in concentrating (when reading the newspaper /watching tv) 8.Felt very restless. 9.Felt subdued or slowed down. 10.Had trouble steeping at night. 11.Suffered from reduced appetite. 12.Suffered from increased appetite. For More Information: Prof. Fabio Sani: