Everyone feels down every now and then but, for some, that low feeling can turn into depression. Some individuals are able to pinpoint a single trigger for the condition developing (e.g. a stressful life event such as a bereavement), but for others depression can be triggered by a downward spiral of events, e.g. losing their job and getting into financial difficulties. 

Several risk factors can also contribute to the onset of depression. These range from unchangeable elements such as being female, having a genetic disposition or low self-esteem, to more modifiable influences such as substance or alcohol misuse and having obsessive compulsive tendencies. Certain illnesses can also play a part, in terms of the stress resulting from having a serious or chronic condition, but also the symptoms themselves, such as depression resulting from hypothyroidism. A history of abuse and having other mental health problems, including dementia, also increase the risk of developing depression.