Patients with coronary heart disease who experience persistent moderate to severe mental distress face a much higher risk of death, according to a new study published online in the journal Heart. But no such link was found for those experiencing persistent mild or occasional distress over the long term.
Although prior research has suggested a link between anxiety/depression and an increased risk of heart attack and stroke, most of these studies were conducted soon after the event, and were based on a single assessment, say the researchers. And the definitions of chronic/persistent stress in other longer term studies have varied widely.
For the new study, the researchers looked at the association between occasional or persistent mental distress and the risk of death in 950 people (aged 31 to 74) with stable coronary heart disease. All of the participants were part of the Long Term Intervention with Pravastatin in Ischaemic Disease Trial and had had a heart attack or been admitted to hospital for unstable angina in the preceding three to 36 months.
To gauge levels of mental distress, the participants completed a validated general health questionnaire at six months, one, two, and four years after the event.
Mental distress was rated according to severity and the length of time it lasted at each of the assessments: never distressed; occasional (of any severity); persistent mild distress on three or more occasions; and persistent moderate distress on three or more occasions. The patients’ health and survival were then tracked for an average of 12 years.
During the monitoring period, 398 people died from all causes and 199 died from cardiovascular disease.
According to the questionnaire, 587 (62 percent) of participants said they had not been distressed at any of the assessments, while around one in four (27 percent) said they had experienced occasional distress of any severity. Around one in 10 (eight percent) said they had experienced persistent mild distress, and 35 people (3.7 percent) complained of persistent moderate distress.
Patients in this last group were nearly four times as likely to have died of cardiovascular disease and nearly three times as likely to have died from any cause as those who said they had not been distressed at any of the assessments.
No such associations were observed among patients who had reported persistent mild distress or those who said they had only experienced it occasionally. The findings remained true even after adjusting for other potentially influential risk factors.
Since this is an observational study, no firm conclusions can be drawn about cause and effect, say the researchers. And confining the assessments to a period of four years might have underestimated the true impact of persistent distress.
Nevertheless, the researchers say that the increase in risk of death was substantial. “These findings suggest that in patients with stable [coronary heart disease], long term mortality risk is related to the cumulative burden of psychological distress,” they wrote.
In a linked editorial, Dr. Gjin Ndrepepa of the Technical University, Munich, Germany, describes the research as an “important and elaborative study which helps to uncover the intricate relationship between psychological distress and cardiovascular disease.”
He said mental distress activates the sympathetic nervous system and boosts stress hormone levels, which, if persistent, can produce potentially harmful physiological changes, some of which may be permanent. Distress can also prompt unhealthy behaviors.