Psychological distress as a risk factor for stroke-related mortality.

In this issue, May et al report that psychological distress is a predictor of fatal ischemic stroke. What is “psychological distress”? It is a nonspecific term that encompasses sadness, frustration, anxiety, and a number of other negative mood states. It includes both mild and severe forms of these mood states, as well as both transient and persistent ones. It also refers both to symptoms of psychiatric disorders and to normal emotional responses to adversity. Although several varieties of psychological distress have been investigated as potential risk factors for cardiovascular or cerebrovascular disease in community cohorts, and as risk factors for cardiac events, stroke, and mortality in patients with established coronary or cerebrovascular disease, depression is the variety of psychological distress that has received the most attention in all of these lines of research. Psychological distress, particularly in the form of depression, has a number of adverse effects in stroke patients. It impairs social functioning and quality of life1 and interferes with the recovery of motor2,3 and language functions.3 It may also be a risk factor for stroke and stroke-related mortality.4–6 In a 14-year follow-up of 2201 middle-aged male participants in the Caerphilly study, May et al report that psychological distress, as measured at baseline by the 30-item version of the General Health Questionnaire (GHQ-30), was an independent risk factor for fatal ischemic stroke, after adjusting for potential confounds. In contrast, the hazard ratios for nonfatal ischemic stroke and for transient ischemic attack (TIA) were not statistically significant, even in univariate analyses. Because this is the first study to conduct separate analyses of fatal and nonfatal stroke, the findings represent a unique contribution to this line of research. The results raise a number of questions about the relationship between psychological distress and stroke. First, in the Caerphilly cohort, as in many prospective studies of psychological risk factors for adverse health outcomes, we know something about the psychological state of the subjects at the time of enrollment but nothing about the course of their psychological distress over the follow-up interval. In this study, cerebrovascular events were ascertained as long as 14 years after the subjects were classified as either currently distressed or not distressed. Presumably, the risk of fatal ischemic stroke is related either to the cumulative exposure to psychological distress during the follow-up interval or to the level of distress just prior to the fatal event, not simply to the presence of distress at an essentially arbitrary point in time years before the event. Furthermore, all we know about the psychological state of the subjects is that they were distressed at enrollment. We do See article on page 7