What damage is caused by long-term use of antidepressants?
Anti-depressive drugs experienced a boom at the end of the last century with the development of selective serotonin re-uptake inhibitors, or SSRIs. After a few decades during which frequent prescriptions have been routinely dispensed to individual patients, there are many who have begun to question the long-term use of these antidepressants.
The reason for this is a paradoxical result emerging from statistics from Western countries. There is a drug that is effective; it helps and cures people suffering from depression. But despite this the costs of incapacity and disability benefits keep increasing.
“Of course, working life has become more demanding and it’s difficult to assess the impact of that aspect. But in general the burden of a disease should diminish and not increase when an effective remedy is discovered for that illness,” says Mira Karrasch, head of research in psychology at Åbo Akademi University.
The current care guideline in Finland is that treatment with SSRIs should continue for several months, sometimes even years. It is estimated that close to 450,000 Finns took antidepressants in 2012. Of these over 100,000 had taken these medicines continuously for several years.
“The criteria for diagnosis have changed over the years. The threshold for fulfilling them has been lowered and antidepressants are also being prescribed for other problems than depression,” says Karrasch.
“In Britain the care criteria and recommendations concerning depression have been adjusted. Drugs are used in cases of acute crisis, but combined with a plan for otherwise supporting the person suffering from depression and for gradually discontinuing the medication. They have abandoned the practice which still continues in Finland, according to which antidepressants are something treatments are started with and the drugs are also regarded as a form of maintenance therapy.”
A great deal of research has been conducted on SSRIs, but most medicine studies only last for four to eight weeks, so it is difficult to know what the long-term effects are. However, clinical studies do demonstrate that the risk of recurrence is greater for those who have used antidepressants than those who have been given a placebo.
“There are many medical treatments that have proven to be good or even necessary in the short term, but which cause complications when used for a long period. This is the case with, for example, certain anti-inflammatory drugs. The problem is that there are so few long-term studies on the effects of antidepressants,” says Karrasch.
Why is that?
“Mainly because a long placebo-controlled follow-up study would be very expensive and because the authorities do not require long-term studies in order to acquire a licence to put the pharmaceuticals on the market. Most clinical trials are carried out or financed by the manufacturer, and it’s natural to limit the trials to six-week studies.”
In 2016 the department of psychology at Åbo Akademi University will start a study on how continuous use of antidepressants affects cognitive functions. These include memory, concentration, perception, linguistic, arithmetic and executive functions. The study will mainly focus on working memory, a central guiding function enabling, for example, flexibility in problem-solving situations and the ability to simultaneously process various aspects of everyday life.
“It is known that working memory and the executive functions in general are reduced when a person suffers from depression. The question is to what extent this is caused by the depression as such and to what extent by something else, such as anti-depressive drugs. This is what we aim to answer, and particularly whether the duration of the use of antidepressants is connected to the person’s cognitive ability,” says Karrasch.
The study is made up of two parts. The objective of the first part is to explore whether there is a connection between the number of years a person has used antidepressants and the function of their working memory. The research is conducted in cooperation with the University of Turku in Finland, Swinburne University in Australia and Harvard University in the USA. The aim of the research group is to get 2,000 participants for their study.
In order to achieve such a large sample, the study is carried out on the Internet, using a web-based cognitive testing platform that has been developed within BrainTrain, an internal centre of excellence in research at Åbo Akademi University, headed by professor of psychology Matti Laine.
“If the results turn out to show that those who have used antidepressants for a longer period have a weaker working memory, the question of the causal connection will still remain. Could it be the case that those who primarily have a weak working memory function are more inclined to be depressed and are therefore also more likely to start using antidepressants? This is an option and therefore a forward-looking research approach is also needed,” Karrasch explains.
In the second part of the study new students will be recruited for conducting the same web-based questionnaire and working memory test. The results will be followed up after two and four years, in order to collect comparable data and potentially make it possible to answer the question of whether a weaker working memory capacity has existed prior to the occurrence of depression and the use of antidepressants. This latter part of the study will start in the autumn of 2016 at the earliest.