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Why poor kids may make sicker adults

Nov. 7, 2007
Courtesy Cornell University
and World Science staff

Sci­en­tists have long known that the poor suffer worse health and shorter lives than the rich. Now, re­search­ers have iden­ti­fied what they say are key mech­a­nisms in 13-year-olds that may help ex­plain why this occurs.

The long­er 13-year-olds have lived in pov­er­ty, the less ef­fi­cient their bod­ies be­come in han­dling en­vi­ron­men­tal de­mands, in­ves­ti­ga­tors found in a new study.

This “may be re­lat­ed to the fact that chil­dren who grow up in pov­er­ty have a steep­er life tra­jec­to­ry of prem­a­ture health prob­lems than oth­er chil­dren,” re­gard­less of lat­er suc­cesses in life, said Gary Ev­ans of the Col­lege of Hu­man Ecol­o­gy at Cor­nell Un­ivers­ity in New York. The stu­dy, co-authored by Ev­ans and Cor­nell grad­u­ate stu­dent Pil­young Kim, ap­pears in the No­vem­ber is­sue of the re­search jour­nal Psy­cho­log­i­cal Sci­ence. 

“Muted re­sponses of stress reg­u­la­tory mech­a­nisms, which are part of the car­di­o­vas­cu­lar sys­tem, not only com­pro­mise the abil­ity of the ado­les­cents’ bod­ies to re­spond to such stres­sors as noise, poor hous­ing and family tur­moil but al­so in­di­cate they are suf­fer­ing from more stress-in­duced phys­i­o­lo­gi­cal strain,” said Ev­ans. “It’s very costly to so­ci­e­ty that low-income chil­dren end up get­ting sick prem­a­turely and die younger.”

Ev­ans and Kim as­sessed mark­ers of stress reg­u­la­tory sys­tems by meas­ur­ing over­night lev­els of a stress hor­mone, cor­ti­sol, and blood pres­sure re­ac­ti­vity and recovery af­ter a stres­sor—be­ing asked un­ex­pectedly to do men­tal math prob­lems. The assess­ments were con­ducted in 217 low- and middle-income white ado­les­cents at age 9 and again at 13 in ru­ral New York. 

The re­search­ers as­sessed cu­mu­la­tive phys­i­cal and so­cial risk ex­po­sure by meas­ur­ing crowd­ing, noise and hous­ing qual­ity along with ma­ter­nal and youth re­ports of family tur­moil, separa­t­ion from family and ex­po­sure to vi­o­lence. 

“The study pro­vides yet anoth­er piece of ev­i­dence that pov­er­ty and oth­er chron­ic risk fac­tors in­duce phys­i­o­lo­gi­cal changes that ap­pear to be re­lat­ed to long-term health prob­lems,” said Ev­ans. He al­so sum­ma­rized his find­ings and made pol­i­cy rec­om­menda­t­ions be­fore the plan­ning com­mit­tee of the Rob­ert W. John­son Founda­t­ion Com­mis­sion to Build a Health­i­er Amer­i­ca on Oct. 17 at the Brook­ings In­sti­tu­tion in Wash­ing­ton, D.C.

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Scientists have known for years that poor people have worse health and shorter lives than the rich. Now, researchers have identified what they say are key mechanisms in 13-year-olds that may help explain how low socio-economic status degrades health. The longer 13-year-olds have lived in poverty, the less efficient their bodies become in handling environmental demands, the investigators found. This “may be related to the fact that children who grow up in poverty have a steeper life trajectory of premature health problems than other children,” regardless of later successes in life, said Gary Evans of the College of Human Ecology at Cornell University in New York. The study, co-authored by Evans and Cornell graduate student Pilyoung Kim, appears in the November issue of the research journal Psychological Science. “Muted responses of stress regulatory mechanisms, which are part of the cardiovascular system, not only compromise the ability of the adolescents’ bodies to respond to such stressors as noise, poor housing and family turmoil but also indicate they are suffering from more stress-induced physiological strain on their organs and tissues,” said Evans. “It’s very costly to society that low-income children end up getting sick prematurely and die younger.” Many studies have found that childhood poverty affects long-term morbidity, or frequency of illnesses and diseases, and mortality. But why is unknown. Evans and Kim assessed markers of stress regulatory systems by measuring overnight levels of a stress hormone, cortisol, and blood pressure reactivity and recovery after a stressor—being asked unexpectedly to do mental math problems. The tests were conducted in 217 low- and middle-income white adolescents at age 9 and again at 13 in rural New York. The researchers assessed cumulative physical and social risk exposure by measuring crowding, noise and housing quality in conjunction with maternal and youth reports of family turmoil, separation from family and exposure to violence. “The study provides yet another piece of evidence that poverty and other chronic risk factors induce physiological changes that appear to be related to long-term health problems,” said Evans. He also summarized his findings and made policy recommendations before the planning committee of the Robert W. Johnson Foundation Commission to Build a Healthier America on Oct. 17 at the Brookings Institution in Washington, D.C.