People with physical illness are at an increased risk of depression, which is linked with a worse prognosis and reduced adherence to treatment. Unfortunately, data on the use of antidepressants in physically ill patients is lacking. Extra care must be taken in prescribing antidepressants to this group because of side effects, possible impact on the liver and kidneys, and the risk of drug interactions.
A recent review looked at the efficacy of antidepressants in physically ill people. It examined 51 studies comparing antidepressants against placebo after six to eight weeks of treatment.
Pooled results showed that antidepressants were significantly better than placebo for tackling depression. However, dropout rates were higher than on placebo, due to side effects including dry mouth and sexual dysfunction. The authors, from King’s College London, London, UK, say that the evidence supports antidepressants, but that further research is required in this population.
Depression is common in Parkinson’s disease, a degenerative disorder of the central nervous system. Rates are estimated at eight to 20 percent of patients. When depression occurs alongside Parkinson’s disease, patients are at risk of more rapid cognitive decline and reduced quality of life. “Recognizing and treating depression in the context of Parkinson’s disease is important in order to reduce disability and improve prognosis,” say Dr. Petros Skapinakis and colleagues at Bristol University, UK.
They report that, in a recent U.S. survey, 63 percent of the prescriptions for depression in Parkinson’s disease patients were for selective serotonin reuptake inhibitors (SSRIs) and 7.5 percent for tricyclic antidepressants (TCAs). They add that treatment of depression in Parkinson’s disease and other medical illnesses poses particular problems.
For example, most antidepressant trials exclude patients with medical illnesses, so results cannot be generalized to these patients. Diagnosis and measures of depression severity in patients with physical diseases may be more difficult because of overlapping symptoms, such as physical changes, fatigue, insomnia, sleep disorders, weight loss, and cognitive dysfunction. In addition, trials of antidepressants in medical illness are usually carried out by independent researchers and are often small.
The Bristol team reviewed ten trials of antidepressants for depression in Parkinson’s disease. Analysis suggested that neither SSRIs nor TCAs were significantly better than placebo. But they write that, due to the limited number of studies and small group sizes, a possible effect cannot be discounted.
“Our results show that the current clinical practice is not supported by strong evidence,” they state, but there is the possibility that patients with Parkinson’s disease may need to take higher doses of antidepressants.
Professor Graeme C. Smith of Monash University, Victoria, Australia, agrees that prescribing antidepressants for patients with physical illness “poses a considerable challenge” despite the fact that the combination is common and brings increased risks.
Studies have been carried out on patients with cancer, diabetes, HIV/AIDS, cardiovascular disease, pulmonary (lung) disease, kidney disease, and stroke, but there are methodological problems in many of these trials, and “their conclusions must be regarded as tentative.”
Professor Smith says, “There were insufficient data for the trials to be able to reach conclusions about the efficacy and acceptability of different types of antidepressants in the physically ill, and about the indications for specific types of antidepressants in specific physical illnesses.”
Guidelines often depend to a large extent on consensus opinion, he believes. His 2002 review found that psychiatrists prescribed antidepressants for 41 percent of physically ill patients with confirmed DSM-IV mood disorder, anxiety disorder, or adjustment disorder with depressed or anxious mood.
“Despite the problems involved, and without adequate practice guidelines, psychiatrists were using antidepressants in physically ill inpatients at a rate similar to that used in the wider population,” he explains. The review also showed that the percentage of patients treated with an antidepressant increased significantly over time, accounted for mainly by greater use of SSRIs.
The choice of drug depended on factors including age, seriousness of psychiatric illness, type of physical illness, presence of pain, pregnancy, and ongoing medication. Heart disease patients were less likely to be given TCAs, due to previous links with irregular heart rhythm. SSRIs may have a beneficial effect in heart disease, but this is still unclear.
On the other hand, TCAs were the preferred choice for patients in pain, and for those also taking antipsychotic drugs. “This may reflect the perception that TCAs are more effective in severe depression,” says Professor Smith. He states, “Evidence-based guidelines for the management of patients with physical/psychiatric comorbidity are required.”
Dr. K. Ranga Krishnan of Duke University, NC, points out that “depression with medical comorbidity is the norm rather than the exception.” Although data are limited, he believes, “the available evidence suggests that depression concomitant with medical illness can be treated.”
SSRIs have demonstrated potential usefulness in depressed patients with heart disease, diabetes, dementia, and Parkinson’s disease, he writes, concluding, “Large-scale trials are needed to assess not only the safety and effectiveness of agents for the treatment of depression in comorbid illness, but also the effects of depression on the course of the medical illness itself.”
Rayner, L. et al. Antidepressants for depression in physically ill people. Cochrane Database of Systematic Reviews, March 2010, Issue 3, Article Number CD007503.
Skapinakis, P. et al. Efficacy and acceptability of selective serotonin reuptake inhibitors for the treatment of depression in Parkinson’s disease: a systematic review and meta-analysis of randomized controlled trials. BMC Neurology, published online June 21, 2010.
Smith, G. C. et al. Consultation-liaison psychiatrists’ use of antidepressants in the physically ill. Psychosomatics, Vol. 43, May-June 2002, pp. 221-27.
Krishnan, K. R. Treatment of depression in the medically ill. Journal of Clinical Psychopharmacology, Vol. 25, August 2005, pp. S14-8.