The European Federation of Neurological Associations has published a booklet that is intended to help people who may have neurological symptoms and conditions, as well as anybody who is interested. Here's an extract from the booklet that handles the symptom of depression. Robert Griffith, Medical Editor.

Depression - What is it?

Although often said to be a psychiatric or mental problem, depression and anxiety may reflect brain and nervous system dysfunction. Around one in six people experience depression at some time in their lives, and it is most common in people aged between 25 and 44. Depression is a state of low mood and loss of interest in previously pleasurable activities. The person may feel apathetic, lacking in self-worth and dejected. In some people there may also be:

• loss of appetite
• sleep disturbance
• impaired concentration
• feelings of guilt
• disorders of behaviour
• suicidal thoughts
• periods of hyperactivity (bipolar, manic-depressive illness)
• delusions and/or hallucinations
• confusion and pseudodementia, in which forgetfulness and disinterest accompany depression.

What might it mean?

Depression is not the same as grief - which is a natural reaction to the death of a loved one or an adverse event or situation (e.g. problems at work). Prolonged, severe or unexplained depression requires medical investigation. The underlying causes may be difficult to ascertain; often, depression has no single cause but is a reaction to a combination of factors. It should also not be assumed that depression is solely attributable to 'psychological' causes until certain disease processes (e.g. infection, endocrine problems) have been ruled out and evaluation of the brain and nervous system has been performed. Depression commonly occurs in neurological conditions such as stroke, Parkinson's disease and headache. Depression is also a major problem in those who have a serious debilitating illness and in their carers.

Should I see my doctor about it?

Consult your doctor if:

• there is no apparent reason for your depression
• depression is interfering with your relationships, work or social life
• depression is prolonged or seems to be worsening
• you think medication may be making you depressed
• sometimes you are depressed and at other times excited and active
• depression is combined with other symptoms (e.g. confusion, lethargy, or headache).

A person who is depressed may appear to be unwilling or unable to seek medical attention. In this situation, it may be appropriate for a family member or friend to offer encouragement in getting help or, indeed, to contact a doctor for further advice.

When might my doctor want to refer me to a specialist?

• When your depression is not responding to treatment.
• When your doctor considers that further neurological testing or brain scanning (when available) is required.