The increase probably derives from greater awareness of mental health problems rather than the nation becoming more miserable, although it is also partly caused by the increasing use of selective serotonin reuptake inhibitors, the new class of drugs which includes the controversial drug Prozac.
SSRIs, whose prescriptions rose by 732 per cent, have fewer side-effects than the older tricyclic antidepressants and those who take them are less likely to discontinue the course of treatment.
The figures were revealed in a report in the British Medical Journal and was drawn up by a team from St George's Hospital, London, led by Dr Richard Martin.
Between 1990 and 1995 a representative sample of 250 doctors was monitored every three months for prescriptions of antidepressants. The subjects were patients who had begun a new course of antidepressant or had their treatment stopped and changed by their doctors.
The team found that patients were significantly less likely to discontinue SSRIs compared with tricyclics. The ratio of total discontin- uations to inceptions was 22 per cent for SSRIs compared with 33 per cent for tricyclics.
However there was more switching away from SSRIs when they fail [72 per cent] compared with 58 per cent for tricyclics.
Dr Martin said the increased levels of prescription were probably based on an increased awareness of depression - in the past more than half of sufferers who would have benefited from antidepressants were not even diagnosed.
"It may not necessarily be that we are more miserable but that GPs are making better attempts to recognise this illness in their patients," he said.
Active marketing of SSRIs by the drugs companies has also been an important factor in their widespread adoption.
The increase in the levels of anti-depressant use in Britain reflects a similar trend in the US where Prozac in particular has become popular with patients and doctors.
The effects of the change are not completely clear and many people who rely on antidepressants have difficulty when their prescriptions run out.
"There is no doubt that patients get better and when you stop them you need to wean them off gradually," said Dr Martin.
The report, which purely examines prescription levels rather than ana- lysing their effect, warns that the rise in the use of SSRI antidepressants, which are far more expensive, is "potentially a huge burden on the NHS budget".
Conventional antidepressants were first brought in in the 1950s and are known as the tricyclics because of their chemical structure. The precise way in which they act to relieve depression is still unclear, but it is probably linked to the finding that tricyclics increase the levels of several chemical messengers (neurotransmitters) in the brain.
SSRIs, on the other hand, work by raising the levels of a mood- enhancing chemical called serotonin in the brain and reversing the chemical changes in the brain that occur with depression.Reuse content