The Pharmaceutical Journal
Vol 270 No 7240 p357
15 March 2003

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Patients who stop antihypertensives may be suffering from depression

Patients who stop taking antihypertensive medication may be suffering from anxiety or depression that leads them to misinterpret symptoms as adverse drug effects, researchers suggest.

In a study involving 233 patients, researchers from the Royal Hallamshire Hospital, Sheffield, and the University of Bristol found that episodes of drug intolerance were related to psychiatric morbidity. Furthermore, this relationship was entirely explained by episodes of intolerance that could not be attributed to the pharmacological action of the drug.

"When faced with a hypertensive patient who has experienced intolerance to several different drugs, particularly with adverse effects that are not typical for the drugs prescribed, possible psychiatric factors should be considered and explored," they say.

The researchers analysed the case notes of all patients who attended a hypertension clinic in Sheffield over one year. They identified patients with documented intolerance to two or more antihypertensive drugs and sent them a questionnaire to determine how many had experienced panic attacks, panic disorder, anxiety or depression. Questionnaires were also sent to a control sample of patients with no documented episodes of drug intolerance.

The researchers found that episodes of non-specific intolerance (ie, intolerance due to symptoms not explained by the pharmacological action of the antihypertensive drug) were associated with panic attacks and depression (P=0.008 for each). Psychiatric diagnoses were recorded for seven (39 per cent) of 18 patients with four or more episodes of non-specific intolerance, nine (19 per cent) of 48 patients with two or three episodes and 25 (15 per cent) of 167 patients with one episode or no episodes.

The researchers say that because drug-specific intolerance was not associated with psychiatric morbidity, psychiatric problems were more likely to be the cause rather than the consequence of repeated episodes of drug intolerance. They suggest that patients with psychiatric problems might ascribe unfamiliar symptoms to their medication or may misinterpret symptoms of their psychiatric illness as adverse drug effects. Another possible explanation could be that biochemical changes associated with psychiatric disorders increase the chance that antihypertensive drugs provoke adverse effects.

"Effective treatment of coexistent psychiatric disorders could increase the acceptability of antihypertensive drugs, and thus enhance blood pressure control and reduce the risk for cardiovascular complications," the authors conclude (Archives of Internal Medicine 2003;163: 592).

Study author Dr Peter Jackson, of the Royal Hallamshire Hospital, told The Journal that prescribers and pharmacists seemed to recognise the problem of non-specific drug intolerance among patients with chronic conditions but that it had not been formally studied.

"We did not investigate solutions to the problem although many such patients will have psychological problems worthy of treatment in their own right. We are currently investigating methods of increasing concordance in such patients," he said.