We use the term depression to mean a great many things. People might say they feel depressed because their jeans no longer fit. They may feel depressed because a favorite TV series has just finished. The use of the term in these situations is pretty tongue in cheek, but even within the context of mental health, the experience of depression varies from mild to major - two sides of the same condition that are actually poles apart.
When psychiatrists and psychologists refer to clinical depression, they think of a cluster of signs (the things we see) and symptoms (the things we feel). The severity of symptoms will vary according to the nature of the depression but it will affect emotions, thought processes, behavior and the physical functioning of the person affected. So, let's take a look at each of these in turn.
Emotional upsets, often referred to as 'affective' symptoms, appear to be the most obvious symptom of depression. Ask most people which emotions are affected and they will probably say the person becomes very sad and miserable. It's true that sadness is associated with depression but actually a more obvious sign is irritability. In fact many people with depression talk about feelings of apathy, or lack or interest and pleasure, rather than the emotion of sadness. Things lose their appeal and even the accomplishment of a job well done holds little or no satisfaction. We call this anhedonia, and it is one of the most common features of depression.
Thoughts processes (cognitions) have been the focus of much attention in research into depression. This is due to the fact that depression is often as much about ways of thinking as it is moods. Self-criticism and low self-esteem are common. The negative thinking that accompanies depression distorts the view of self as much as the world the person lives in. Many depressed people also find decision making extremely difficult. Depression affects other cognitive processes such as memory, concentration and problem-solving. In summary, the cognitive aspects of depression are a combination of intrusive distracting and often irrelevant thoughts, and problems in mobilizing other cognitive capacities.
It's often said that you can see depression simply by observing the behavior of someone who suffers with it. This isn't strictly true as many people are fairly adept at masking their depression in certain situations. What is common is for people to withdraw from situations where they have a choice to participate or not. As depression deepens, more time might be spent in bed. The person may become visibly slower in their actions. They may slump, shoulders bent, head down and move as though they carry the weight of the world. Facial expressions may become less animated, and facial muscles relax so the eyes and mouth droop. These are all signs of psychomotor retardation.
Yet another group of people with depression show signs of agitation. They may fidget, use lots of gestures and appear restless. This is a sign of depression with anxiety - a common combination. Some clinicians regard psychomotor retardation as a sign of 'pure' depression, which tends to be more responsive to antidepressant medication.
Changes in appetite (loss or increase), sleep and energy levels are some of the most common physical symptoms of depression. Sleep disturbance is very common in people with unipolar depression and may involve problems in getting to sleep, too much sleep or waking too early in the morning. Disturbed sleep is both a cause and a consequence of depression.
The experience of depression varies from person to person although there are common threads. There may also be different forms of depression, all with different causes, which respond differently to various forms of treatments .