"Long before it's in the papers"
February 16, 2011

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Remote community evades scourges of aging

Feb. 16, 2011
Courtesy of the University of Southern California
and World Science staff

A re­mote Ec­ua­do­re­an com­mun­ity of peo­ple who share a dwarf­ism gene al­so al­most nev­er ex­pe­ri­ence can­cer, di­a­be­tes or strokes, com­mon scourges of ag­ing, a study has found.

In­deed, the re­search­ers dis­cov­ered, it seems the only rea­son this popula­t­ion does­n't en­joy un­usu­ally long life­spans is that it suf­fers a high rate of ac­ci­dents and sub­stance abuse. That aside, the sci­en­tists added, the muta­t­ion may of­fer clues to treat­ments or di­ets that could pro­tect the rest of us from ag­ing-re­lat­ed dis­eases.

The peo­ple “ap­pear to be rel­a­tively hap­py and nor­mal,“ yet “there are a lot of strange causes of death, in­clud­ing many that are alcohol-re­lat­ed,“ not­ed cell bi­ol­o­gist Val­ter Longo of the Uni­vers­ity of South­ern Cal­i­for­nia, one of the re­search­ers. The 22-year study none­the­less sug­gests growth-stunting muta­t­ions al­so may stunt two of hu­man­ity's worst dis­eases, he added.

The re­search­ers, led by Longo and Ec­ua­do­ri­an en­do­cri­nol­ogist Jaime Guevara-Aguirre, fol­lowed a re­mote com­mun­ity on the slopes of the An­des moun­tains. Many of its mem­bers have Laron syn­drome, a de­fi­cien­cy in a gene that pre­vents the body from us­ing growth hor­mone. The sci­en­tists fol­lowed about 100 such peo­ple and 1,600 rel­a­tives of nor­mal height.

Over 22 years, the team doc­u­mented no cases of di­a­be­tes and one non-lethal case of can­cer in Laron's sub­jects. The find­ings are pub­lished in the re­search jour­nal Sci­ence Transla­t­ional Med­i­cine. Among rel­a­tives liv­ing in the same towns dur­ing the same time pe­ri­od, 5 per­cent were di­ag­nosed with di­a­be­tes and 17 per­cent with can­cer.

Longo and his team con­clud­ed that growth hor­mone ac­ti­vity has many down­sides, at least for adults past their grow­ing years. “The growth hor­mone receptor-de­fi­cient peo­ple don't get two of the ma­jor dis­eases of ag­ing. They al­so have a very low in­ci­dence of stroke, but the num­ber of deaths from stroke is too small to de­ter­mine wheth­er it's sig­nif­i­cant,” Longo said.

He added that, out of caution, any treat­ment for pre­ven­tive re­duc­tion of growth hor­mone would have to show few­er and milder side ef­fects than drugs used against a con­firmed dis­ease. And any pre­ven­tive treat­ment would tar­get only adults with abnor­mally high growth hor­mone ac­ti­vity.

An­i­mal stud­ies pro­vide ev­i­dence for the health ben­e­fits of block­ing growth hor­mone, Longo and col­leagues not­ed. Groups led by John Kopchick of Ohio Uni­vers­ity and An­drzej Bartke of South­ern Il­li­nois Uni­vers­ity achieved a rec­ord 40 per­cent life­span ex­ten­sion with growth fac­tor de­fi­cient mice in stud­ies pub­lished in 2000 and 1996, re­spec­tive­ly. Lat­er, the re­search­ers linked growth fac­tor de­fi­cien­cy to re­duced tu­mor risk.

The U.S. Food and Drug Ad­ministra­t­ion has al­ready ap­proved drugs that block growth hor­mone ac­ti­vity in hu­mans. These are used to treat ac­ro­meg­a­ly, a con­di­tion re­lat­ed to gi­gantism.

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A remote Ecuadorean community of people who share a dwarfism gene also almost never experience cancer, diabetes or strokes, common scourges of aging, a study has found. Indeed, the researchers discovered, it seems the only reason this population doesn't enjoy unusually long lifespans is that it suffers a high rate of accidents and substance abuse. That aside, the scientists added, the mutation may offer clues to treatments or diets that could protect the rest of us from aging-related diseases. The people “appear to be relatively happy and normal,“ yet “there are a lot of strange causes of death, including many that are alcohol-related,“ noted cell biologist Valter Longo of the University of Southern California, one of the researchers. The 22-year study nonetheless suggests growth-stunting mutations also may stunt two of humanity's worst diseases, he added. The researchers, led by Longo and Ecuadorian endocrinologist Jaime Guevara-Aguirre, followed a remote community on the slopes of the Andes mountains. The community includes many members with Laron syndrome, a deficiency in a gene that prevents the body from using growth hormone. The scientists followed about 100 such people and 1,600 relatives of normal height. Over 22 years, the team documented no cases of diabetes and one non-lethal case of cancer in Laron's subjects. The findings are published in the research journal Science Translational Medicine. Among relatives living in the same towns during the same time period, 5 percent were diagnosed with diabetes and 17 percent with cancer. Longo and his team concluded that growth hormone activity has many downsides, at least for adults past their growing years. “The growth hormone receptor-deficient people don't get two of the major diseases of aging. They also have a very low incidence of stroke, but the number of deaths from stroke is too small to determine whether it's significant,“ Longo said. Longo said that any treatment for preventive reduction of growth hormone would have to show fewer and milder side effects than drugs used against a confirmed disease. And any preventive treatment would target only adults with abnormally high growth hormone activity. Animal studies provide evidence for the health benefits of blocking growth hormone, Longo and colleagues noted. Groups led by John Kopchick of Ohio University and Andrzej Bartke of Southern Illinois University achieved a record 40 percent lifespan extension with growth factor deficient mice in studies published in 2000 and 1996, respectively. Later, the researchers linked growth factor deficiency to reduced tumor risk. The Food and Drug Administration has already approved drugs that block growth hormone activity in humans. These are used to treat acromegaly, a condition related to gigantism.