London, Oct 23 Researchers at the University of Southampton have found that a dramatic rise in antidepressant prescriptions issued by GPs has been caused by a year on year increase in the number of people taking antidepressant drugs on a long-term basis.

They study showed that despite a drop in the number of new patients diagnosed with depression over 11 years, the number of prescriptions doubled.

"We estimate that more than 2 million people are now taking antidepressants long-term over several years, in particular women aged between 18 and 30," said study's lead author Tony Kendrick, a professor in Primary Medical Care of the University's School of Medicine.

The number of prescriptions issued per patient rose from 2.8 in 1993 to 5.6 in 2004.

Prescription Pricing Authority data shows that more than 30 million prescriptions for SSRIs (selective serotonin reuptake inhibitors) such as Prozac and Seroxat, are now issued per year, twice as many as the early 1990s.

University of Southampton researchers found that 90 per cent of people diagnosed with depression are now taking SSRIs either continuously or as repeated courses over several years.

"Our previous research found that although these drugs are said not to be addictive, many patients found it difficult to come off them, due to withdrawal symptoms including anxiety. Many wanted more help from their GP to come off the drugs. We don't know how many really need them and whether long-term use is harmful. This has similarities to the situation with Valium in the past," Kendrick said.

For the study, the researchers analysed all new cases of depression between 1993 and 2005 from anonymous computerised general practice records covering 170 GP surgeries and 1.7 million registered patients.

The study has been published in the printed edition of British Medical Journal (BMJ). (ANI)