The decline of cardiovascular disease in older people is the result of improved health practices, primarily less smoking, and a focus on lowering blood cholesterol via lifestyle change and drugs such as statins. The formation of fatty plaque in blood vessel walls occurs in later life, the condition known as atherosclerosis. The plaque narrows and weakens blood vessels throughout the body. The rupture of a vessel or disintegration of a plaque followed by a a downstream blockage is the mechanism that causes both stroke and heart attack. Atherosclerosis is a consequence of the mechanisms of aging and their downstream consequences, such as raised blood pressure, growing chronic inflammation, as well as oxidative stress that produces toxic oxidized forms of cholesterol. To the degree that this vascular aging has been slowed, or some of its consequences diminished, by the limited means available, cardiovascular disease and strokes will also decline in the older population.
A new study which examined the population of Denmark has found that people age 70 and older are having fewer strokes, and fewer people of all ages are dying from the disease. In older people, researchers found declines in both ischemic stroke, caused by a blockage of blood flow to the brain, and intracerebral hemorrhage, when a blood vessel bursts inside the brain. "Stroke is a leading cause of death and disability in the world. Recent research on the incidence of stroke has been mixed, and some studies have reported an increase among young people. However, our research found no increase in stroke among young people, and it also found the incidence of stroke declining among older people, which is encouraging."
For the study, researchers used national health care registries in Denmark to identify all people in the country hospitalized with a first-time stroke between 2005 and 2018. They identified 8,680 younger adults age 18 to 49 who had a stroke during that time, and 105,240 older adults age 50 and older. Researchers calculated yearly incidence rates for both ischemic and hemorrhagic stroke based on the Danish population. They also calculated incidence rates based on age.
Researchers found the incidence rate of stroke in people 49 and younger remained steady over the course of the study, with around 21 cases of ischemic stroke per 100,000 person-years at the start and end of the study. For intracerebral hemorrhage, the incidence rate in young people was around 2 cases per 100,000 person-years at the start and end of the study. The incidence rates of stroke declined in people 50 and older over the course of the study, with 372 cases of ischemic stroke per 100,000 person-years at the start of the study and 311 cases at the end. For intracerebral hemorrhage, there were 49 cases per 100,000 person-years at the start of the study and 38 cases at the end. However, stroke rates in people in their 50s were stable, with most of the decline in people age 70 and older.
"The improvements we found in survival rates are consistent with improvements in stroke care. We also examined stroke severity and found while mild strokes increased, the most severe cases declined. These changes could be related to improvements in stroke awareness in the general population as well as the care people receive for stroke, including in the ambulance and emergency department prior to hospitalization. Such care has led to faster and improved diagnostics, particularly regarding the mildest of cases."