Although no single symptom is pathognomonic (typical) of depression, certain core features, in the presence of typical mood disturbance, form the basis for diagnosing the syndrome.

If 3 of these additional symptoms are present, antidepressant treatment is likely to be successful.  Patients with 4 or more core symptoms definitely qualify for treatment.

The core symptoms of depression are:

• Psychomotor agitation (emotional restlessness) or retardation
• Change in sleep pattern
• Appetite or weight change
• Loss of energy, extreme fatigue
• Impaired concentration, memory
• Pessimism, poor self-image, feelings of worthlessness, excessive guilt.  These features impart a very distinctive quality to the depressed patient's mood disturbance.  The negative feelings are out of proportion to reality and reflect the ‘cognitive distortions' which accompany depression.
• Recurrent thoughts of death or suicide.  Over 80% of depressed patients admit to having actively contemplated suicide.

Anxiety and Depression
Anxiety symptoms often dominate the clinical picture in depressive illness so that an anxiety state seems a more obvious diagnosis.

A useful guideline for general practitioners is never to diagnose an anxiety state without considering the likelihood that the patient is suffering from depression.

In the past, most of these cases were given benzodiazepines (sedatives, hypnotics), which sometimes brought symptomatic relief and apparent temporary improvement, but left the underlying depression untreated or even caused deterioration.

The general practitioner, who feels that this type of patient requires medication, is advised to give an antidepressant as the first line of treatment.

 Interestingly, antidepressants have also been shown to be the most effective treatment for the ‘traditional' anxiety disorders.

In the presence of anxiety should we prescribe an antidepressant with sedative side-effects?

The sedative side-effects of an antidepressant used to be considered an advantage in these patients and, conversely, less sedating or energizing drugs were recommended for depression associated with psychomotor retardation.  It seemed a common sense approach.

Non-sedating antidepressants are now widely considered to have an equal advantage in all cases of depression, regardless of the degree of psychomotor agitation or retardation.

But, don't these antidepressants cause unacceptable exacerbations in anxious patients?

Unpleasant ‘nervousness' is a recognized side-effect of some of the newer antidepressants and, at the start of treatment, affected patients may feel that their condition is getting worse.  Fortunately, it is usually self-limiting within a short time and most patients can be encouraged to tolerate it.  If necessary, they can be helped over the initial stages of treatment with the addition of a controlled, short course of a benzodiazepine.
Features of Antidepressants

• All of the established antidepressants have equivalent efficacy, improving about 70% of depressed patients.
• Ten days to three weeks is required to effect clinically appreciable improvement.
• All antidepressants have side-effects.

For How Long Should Depression Be Treated?
There are 3 phases of treatment.

1. Acute Phase
2.      This refers to treatment of the acute episode.
3. Continuation Phase

Although the acute symptoms usually subside within 6-8 weeks, the underlying illness takes longer to resolve and the patient remains highly vulnerable to RELAPSE (i.e. return of symptoms after a period of remission).

The risk of relapse is significantly reduced if antidepressant medication is continued for 6-8 months after the patient has responded to treatment.  Currently, the evidence suggests that the continuation dose should be the same as that to which the acute symptoms responded.

Doctors have an obligation to encourage patients to comply with continuation therapy and their task is easier with newer antidepressants, which are generally much better tolerated.

1. Maintenance or Prophylactic Phase

A very high proportion of patients develop RECURRENCE of depression (i.e. a new episode after recovery from a previous one).

 Longitudinal studies suggest that there is a tendency for episodes to increase in frequency and for the duration of remission to be reduced after each episode.

Prophylactic antidepressant medication reduces the risk of recurrence.

The World Health Organization Consensus Statement suggested that prophylactic medication should be considered for all patients having a second episode of depression within a 5-year period.  Additional risk factors include later onset of illness, family history of affective disorder, long duration and severity of episodes, pre-existing Dysthymia and substance abuse.  A high level of co-morbid anxiety also appears to increase the risk of poor long-term outcome.

With regards to dosage, current opinion suggests that "the dose that gets the patient well is the dose that will keep the patient well".