Which comes first: stroke or depression? Study says depression.
People over age 50 with persistent depression have double the risk for stroke compared with their nondepressed, age-matched counterparts, according to findings from a nationally representative cohort study of US adults.
The elevated risk remained in patients whose depression symptoms resolved over 2 years, suggesting that depression and stroke share common cumulative etiologic mechanisms, researcher Paola Gilsanz, ScD, of Harvard T.H. Chan School of Public Health, and colleagues wrote in the Journal of the American Heart Association, published online May 13.
Gilsanz explained that even though the link between depression and stroke is well established, little research has been done examining how changes in depressive symptoms impact stroke risk.
“We were surprised to see that changes in depressive symptoms seem to take more than 2 years to influence risk of stroke,” she told MedPage Today in an email exchange.
Depression May Impact Long-Term Stroke Risk Factors
The researchers noted that biological mechanisms driving the depression-stroke link could be long term — such as the impact on risk factors like hypertension and atherosclerosis, or short term — such as cerebrovascular reactivity or atrial fibrillation.
“If the causal mechanisms linking depression and stroke are exclusively long term, reductions in stroke risk would require years of successful symptom managment,” they wrote … “If causal mechanisms exert their effects in the short term, via fast acting pathways, reduced depressive symptoms might allow nearly immediate reductions in stroke risk.”
In an effort to better understand the impact of remitting depressive symptoms on stroke risk, the researchers analyzed data from the Health and Retirement Study (HRS), which is an NIH-supported, nationally representative study of middle age and elderly people surveyed every 2 years.
The analysis included 16,178 HRS participants who had no history of stroke at study entry and who completed surveys between 1998 and 2010. Stroke was assessed through self-report or doctors’ diagnoses and depression was assessed using a modified Center for Epidemiologic Studies-Depression scale.
The researchers examined whether patterns of depression symptoms characterized across two successive interviews were predictive of incident stroke using Cox proportional hazards modeling adjusted for potential confounders. They also estimated effects stratified by age (≥65), race or ethnicity and sex.
Remitting Depression Linked to Higher Stroke Risk
Among the major findings:
Patients with stable high depression symptoms had more than double the risk for stroke compared with patients with low or no depression symptoms (hazard ratio 2.14, 95% CI 1.69-2.71)
Patients with remitted depression symptoms also had an elevated risk (HR 1.66, 95% CI 1.22-2.26) compared with nondepressed patients.
Stable high depressive symptoms was predictive of stroke in all subgroups and remitted depression symptoms predicted stroke hazard among women (adjusted HR 1.86, 95% CI 1.30-2.66) and non-Hispanic whites (adjusted HR 1.66, 95% CI 1.18-2.33).
“Our findings suggest that effects occur over the longer term through accumulated damage, given that we saw little differential in stroke risk prediction by short-term increases or decreases in depressive symptoms,” the researchers wrote. “Further research should continue to examine possible mediators of the relationship between depressive symptoms and stroke.”
In-Office Depression Screening Important
This findings serve as an important reminder to clinicians that depression and stroke are related, said American Heart Association spokesman Philip B. Gorelick, MD, MPH, of Michigan State University College of Human Medicine, Grand Rapids.
Gorelick told MedPage Today that while many health provider networks have begun to integrate cardiovascular, diabetes and depression care with interdisciplinary teams of health professionals, many individual clinicians still do not recognize the importance of depression as a risk factor for other health conditions.
“I think the clinical message here is that depression screening in the office is important, especially in patients with risk factors for depression,” he said. “It is also a reminder that treating cardiovascular risk factors is especially important in patients who screen positive for depression.”