The wages of sin is dementia.
That is the message that has emerged from two studies in the United States showing that the lifestyle choices people make that cause cardiovascular problems in middle age can lead to dementia later in life.
One study, published in the Journal of Neurology, Neurosurgery and Psychiatry, followed more than 11,000 women and men with atherosclerosis (hardening of the arteries) over a 15-year period.
Researchers found that in that group, all of whom had various cardiovascular problems:
Smokers were 70 per cent more likely to develop dementia than non-smokers;
Those with hypertension - often caused by poor diet, and excess salt consumption in particular - were 60 per cent more likely to develop Alzheimer's disease or other forms of dementia than those with normal blood pressure;
People with type 2 diabetes in middle age, another condition associated with poor diet and inactivity, were twice as likely as those without diabetes to later be admitted to hospital with dementia.
Alvaro Alonso, an assistant professor of epidemiology at the University of Minnesota's School of Public Health and the lead author of the research, said he believes that the findings should prompt earlier and more aggressive intervention.
"Showing that cardiovascular risk factors earlier in life have an impact on dementia later in life gives another reason why we need to intervene with those cardiovascular risk factors," Dr. Alonso said.
A second, unrelated study, published in the medical journal Dementia and Geriatric Cognitive Disorders, found that people with high cholesterol levels in midlife also had an increased risk of Alzheimer's disease and other forms of dementia. The scientists tracked almost 10,000 men and women in California and Finland for four decades.
Researchers found total cholesterol levels of 240 milligrams per decilitre of blood, or higher, in middle age were associated with a 66-per-cent higher incidence of Alzheimer's disease decades later. But the risk actually began to rise at a level of 200, which is considered borderline high.
"Our study shows that even moderately high cholesterol levels in your 40s puts people at greater risk for Alzheimer's disease and vascular dementia decades later," said Rachel Whitmer, an epidemiologist at the Kaiser Permanente in Oakland and the lead researcher.
Neither study examined the exact biological link between cardiovascular risk factors and dementia. But post-mortem studies of brains of people with dementia often show damage to small arteries, suggesting that health conditions such as hypertension and high cholesterol provoke mini-strokes that damage the brain and exacerbate the onset of dementia.
Dr. Alina Solomon, a researcher with the department of neurology at the University of Kuopio in Finland and co-author of the study, said the new research should incite heart and brain researchers and clinicians to work more closely together for the common good of patients.
"Dementia and cardiovascular disease are common major health problems, share several risk factors and often occur simultaneously, interacting with one another," Dr. Solomon said. "A holistic approach that addresses multiple major health problems simultaneously is needed to effectively manage these disorders."
Cardiovascular disease is one of the leading killers of Canadians, claiming 65,628 lives in 2005, the most recent year for which mortality data are available from Statistics Canada. But because of advances in prevention, treatment and surgery, people are also living much longer with symptoms of cardiovascular disease.
Currently, about 500,000 Canadians are living with dementia and within a generation the condition may affect more than one million people across the country, according to the Alzheimer Society of Canada.