Early life adversity through poverty, social isolation or abuse in childhood is linked to heightened reactivity, which can lead to heart disease later on, a leading expert on stress and disease reports.
"Many diseases first diagnosed in mid-life can be traced back to childhood," Karen A. Matthews, PhD, said at the 118th Annual Convention of the American Psychological Association. "Having some bad health habits in your 20s and 30s is part of the reason why people get diseases later on. However, it isn't the whole reason. The evidence shows that certain reactions to adverse childhood experiences associated with lower socioeconomic status, isolation and negative events can affect the disease process."
Matthews is a professor of psychiatry and epidemiology at the University of Pittsburgh. She has published many studies on children's and women's stress, environmental influences and risk for cardiovascular disease.
"It seems that parents' SES [socioeconomic status] affects young adolescents' later risk for cardiovascular disease more than younger children and older teenagers," said Matthews.
Some data suggest that the accumulation of stress across the lifespan increases risk for disease. But there are critical periods where stress has more of an impact, she said. "Our data suggests that this age group is more vulnerable to cardiovascular risks if they are exposed to various stressors because of their hormonal changes and their sensitivity to peer rejection, acceptance and how they interpret others' attitudes towards themselves," she said.
Project Pressure, a study led by Matthews, examined 212 14- to16-year-olds for three years to see whether living in areas of low socioeconomic status was linked to more sensitivity to stress and early signs of heart disease. The sample consisted of equal numbers of blacks and whites, females and males. Participants were healthy; none was morbidly obese. Levels of carotid artery thickening, stiffness of arteries and blood pressure throughout the day and night were used to determine the beginning of disease.
Socioeconomic status measures included parental education, household income, the percentage of poor people living in the neighborhood, percentage of high school graduates and number of assets (e.g., cars, homes, number of bedrooms, insurance, loans and debts).
According to the study, children who were from families of lower socioeconomic status had stiffer arteries several years later. Those living in impoverished neighborhoods had higher blood pressure when monitored for two days at school, and blacks living in poor neighborhoods had more thickening in their carotid arteries. Thicker carotid arteries are associated with later atherosclerosis in the heart. Finally, those who had higher diastolic blood pressure over the three-year period suffered more thickening of their carotid walls. (Diastolic blood pressure -- the second number -- measures the pressure in blood vessels between heartbeats.)
Matthews cited other studies to show more evidence of the connection between stressful childhood events and risk of cardiovascular disease.
In a longitudinal study of 1,037 New Zealand children followed from birth to age 26, researchers found that children who were socially isolated had a higher risk of cardiovascular disease, indicated by higher blood glucose levels, overweight, elevated blood pressure and high cholesterol levels in young adulthood. Social isolation was measured by the parents' reports of children's time being alone and not liked by peers and by children's own reports of loneliness during adolescence and adulthood. The researchers controlled for socioeconomic status, IQ, and unhealthy behaviors in childhood. These findings suggest that chronic social isolation across multiple developmental periods has a cumulative effect and can lead to poor health in adulthood.
Another study conducted by Matthews showed how low socioeconomic status can influence children's reactions to negative situations and, over time, increase the risk of heart disease. A sample of 201 children and adolescents (age 8 to 10 and 15 to 17), of whom half were white and half were black, were presented with negative and ambiguous social situations. The children from poorer homes interpreted the different social situations, including ambiguous ones, as threatening. They also had higher blood pressure and heart rates and higher hostility and anger scores during three laboratory stress tasks.
"Children who have minimal resources both from their families and communities grow up in unpredictable, stressful environments," said Matthews. "Fewer resources make people more susceptible to negative effects of adversity. One way to adapt is to become hypervigilant to head off potential threats. But the consequence of this is to then interpret events as threatening, even when they are not, and start to mistrust people. Interactions with others then become a source of stress, which can increase arousal, blood pressure, inflammation levels and deplete the body's reserves. This sets up risk for cardiovascular disease."
Matthews recommended improving the quality of education for these children, improving parenting skills -- especially for single parents -- and building positive social relationships to minimize stress reactions and lower the risks of disease.
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