New research on antidepressant addiction and withdrawal

A study of more than 1800 New Zealanders has found a significant number of people on antidepressants believe the drugs are addictive and more than half report experiencing withdrawal symptoms.

The research, by University of Auckland researchers Dr Claire Cartwright and Dr Kerry Gibson from the School of Psychology, was led by Professor John Read of the University of East London and is the largest so far attempting to track long-term use of antidepressants and issues of withdrawal and addiction.

Antidepressant prescription rates are rising in many western industrialised nations with an estimated 10 percent of people prescribed the drugs in countries such as the United States and United Kingdom. In New Zealand, its estimated one in nine adults are prescribed antidepressants each year with the number of prescriptions thought to be rising at five percent per annum.

This research investigated long-term use of antidepressants in an online survey by asking participants who had been using the drugs about whether or not they experienced side effects, including withdrawal symptoms and addiction.

“Given some evidence from research conducted in the UK, it appears that the rise in antidepressant prescriptions can be explained by repeat prescriptions rather than new patients,” Dr Cartwright says.

“So given that people are staying on antidepressants for longer, the issue of whether or not people feel addicted and whether or not those who stop taking them are experiencing withdrawal symptoms becomes important.”

A total of 1829 New Zealanders took part in the survey and of those, 44 percent had been taking antidepressants for more than three years and were still taking them.

As the survey was self-selecting, respondents not only chose to take part but could also choose whether or not to answer questions about specific topics.

Of the 1367 who filled out the section related to withdrawal symptoms, more than half – 54.9 percent - reported some withdrawal effects, with 25.1 percent reporting the effects as severe while 45.1 percent of participants reported no symptoms.Of the 1521 people who filled out the section on addiction, 72 percent reported antidepressants were ‘not at all’ addictive, but 27.4 percent reported some level of addiction. Of those reporting some level of addiction, 6.2 percent described the addiction as severe, 9.4 percent as moderate and 11.8 percent as mild.

“This study was not designed to definitively answer the question of whether or not antidepressants are addictive because there are a range of expert definitions of addiction,” Dr Read says.

“But what it did set out to do was make a significant contribution to the estimated rates of long-term usage in relation to self-reported withdrawal and addiction by directly asking users about their experience. The results point to a significant number of people prescribed antidepressants who have experienced some withdrawal effects and who believe the drugs are addictive.

”Criteria for participation in the online survey included having been prescribed antidepressants within the last five years and being at least 18 years old."