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There are more than 65 million Hispanic and Latino people living in the U.S. – the second-largest racial or ethnic minority population in the country. Yet when it comes to heart and brain health, less may be understood about this population than any other.

Researchers say the reasons for this are complex, but two stand out: While often lumped together, people of Hispanic origin are not actually one group, but many. And for decades, nobody studied them.

In fact, until the 1980s, nobody even counted them – or collected comprehensive data about their health. Half a century later, many questions remain unanswered.

"For years, all we had was anecdotal evidence about health trends," said Dr. Lindsay Fernández-Rhodes, an associate professor of biobehavioral health at Penn State College of Health and Human Development in University Park, Pennsylvania. "Before you have the data to measure something, it may appear that it doesn't exist."

Defining the population: Hispanic or Latino?

Many people and entities, including the federal government, lump people of Hispanic and Latino origin together, but the two terms have different meanings.

Hispanic refers to people with ancestry from a country where Spanish is the primary language spoken, including Spain or any of the countries it colonized. Latino refers to people with origins anywhere in Latin America and the Caribbean. The Census Bureau uses the two terms to cover anyone whose family has origins in Cuba, Mexico, Puerto Rico, South or Central America or places from any "other Spanish culture or origin." People of Hispanic and Latino origins may be of any race.

This covers a broad range of cultures, geographic origins, languages, nutritional preferences and socioeconomic statuses, with differences in how people access the health care system. And all of these factors can affect a person's health, said Dr. Fátima Rodríguez, an associate professor of cardiovascular medicine at Stanford University School of Medicine in California.

"Studying all of these people together does not make sense," she said. "We're starting to recognize this is a highly diverse group of people, and the heterogeneity and diversity within the Hispanic population make it impossible to generalize to all of these groups. We need to consider how social determinants of health affect each group individually."

Early focus largely on people with Mexican heritage

Hispanic and Latino people have been part of the U.S. since before the nation's beginning, especially in Texas, California, Nevada, Utah, New Mexico and Arizona, which once belonged to Mexico. Because of the large numbers of Mexican American people living there, early studies of Hispanic cardiovascular health focused on this population.

Some of the first studies looked at people of Mexican descent living in and around San Antonio, Texas. During the 1970s, researchers were seeking clues about what was causing a decline in heart disease mortality rates in the U.S. They thought they'd find them by comparing health trends for people of differing cultural and economic backgrounds, so for white men and women to those for people with Spanish surnames. They theorized that because Hispanic people had lower socioeconomic status, they would have higher death rates than their more affluent white peers. They did not. Mexican American women, in particular, were seeing declines in heart disease death rates that puzzled researchers.

This was the first indication that Hispanic and Latino populations might have differences that merit investigation, but "it was not a representative sample of Hispanics and Latinos across the U.S.," said Dr. Larissa Avilés-Santa, director of clinical and health services research at the National Institutes of Minority Health and Health Disparities. Nonetheless, "we began to recognize that something was happening here."

Opening the door to research

Researchers couldn't look at national data for health trends among Hispanic people because there wasn't any.

It wasn't until 1980 that a question regarding Hispanic or Latino heritage was included on U.S. census forms. Once this demographic data was collected, it allowed researchers to construct studies such as the , or HHANES. It collected comprehensive data about the health and nutritional status and needs for three Hispanic subgroups: Mexican Americans in five Southwestern states; Cuban Americans in Dade County, Florida; and Puerto Ricans in New York City and the surrounding area.

The 1982 to 1984 survey was the first time the National Center for Health Statistics looked at a specific population. However, it covered only 76% of the Hispanic population living in the U.S. at the time. Researchers collected socioeconomic, health and demographic data and conducted physical and dental exams and a series of lab tests, creating what was then the largest and most comprehensive health database for this population in the U.S.

The medical data collected included the presence of chronic conditions such as diabetes, high blood pressure, heart disease and depression, along with information on insurance coverage, use of the health care system and exposure to environmental toxins such as lead.

"Really, what it took was recognizing from the census data that there was a growing demographic group that warranted study," Fernández-Rhodes said. "And that's when a fuller picture began to emerge."

The Hispanic paradox

As data began to surface, some puzzling questions arose.

In 1986, of two decades of studies on the health status of Hispanic people in the Southwest, most of whom were of Mexican origin, found an anomaly in health trend data between Hispanic and non-Hispanic populations that quickly became known as the "Hispanic paradox."

The researchers noted that Hispanic people, who faced socioeconomic disadvantages similar to Black people, nonetheless experienced better health, more in line with their white, non-Hispanic peers. Compared to non-Hispanic white people, Hispanic participants had similar infant mortality rates, life expectancy and death rates for cardiovascular disease and cancer.

Subsequent studies found even lower heart disease mortality rates for Hispanic populations than their non-Hispanic white peers. In contrast, studies consistently found Hispanic people in the U.S. had higher rates of diabetes and other cardiovascular risk factors, such as metabolic syndrome, obesity and a sedentary lifestyle.

"There was a striking epidemiological observation that this population that had adverse socioeconomic factors also had higher rates of several cardiovascular risk factors, but lower mortality rates from heart disease than the non-Hispanic population," Rodríguez said.

Puzzled over the paradox, researchers turned their attention to investigating what might be protecting the Hispanic population and whether those protections could be broadly applied. Theories emerged suggesting that people who immigrated to the U.S. were healthier than those who stayed behind, that people who became sick in the U.S. returned to their countries of origin and that the paradox applied only to people born outside the U.S. and not to those in subsequent generations.

But the Hispanic paradox began to unravel once researchers started digging deeper into the differences among the ethnic subgroups and looking at health trends among their offspring.

A 'landmark' study

In 2008, researchers began collecting health data from a target population of 16,000 Latino adults in Miami, San Diego, Chicago and the Bronx borough of New York City. Participants were of Cuban, Puerto Rican, Dominican, Mexican and Central and South American descent.

Called the , or HCHS/SOL, it was the largest, most comprehensive long-term study of Latino health and disease in the U.S. It aimed to determine the role acculturation played in the prevalence and development of disease and identify factors that may be protective or harmful to the health of these populations.

HCHS/SOL "was a landmark study that intentionally focused on four regions of the U.S. that would capture a number of Hispanic heritages and reflect the diversity seen in the national population," Fernández-Rhodes said. "Initially, the conclusion had been that this was a healthy population. But it turned out that wasn't always true."

Overall, the data showed that in these four large U.S. Hispanic communities, people had the same or higher risk for heart disease and stroke as their non-Hispanic white peers, but there were major differences among Latino ethnic groups.

One of the first analyses to use HCHS/SOL data, published in the in 2012, found 80% of Hispanic men and 71% of Hispanic women overall had at least one cardiovascular risk factor, but those factors differed by age, sex and ethnic group. For example, Puerto Rican women had the highest rates of obesity at nearly 51%, compared to 31% of South American women and 27% of South American men. Central American men had the greatest prevalence of high cholesterol at nearly 55%, compared to 31% of South American women. But 1 in 4 Puerto Rican men and women had three or more risk factors, more than any other group.

The study in JAMA also revealed differences that appeared to be driven by acculturation. Significantly higher rates of cardiovascular risk factors were found among people who were born in the U.S., lived here for 10 or more years and preferred English.

"As Hispanic populations acculturate or assimilate into the U.S., they may become less physically active and eat more processed food," Rodríguez said. "Their health may paradoxically get worse, even if their socioeconomic status gets better."

Studies over the past two decades have shed more light on the complexities of cardiovascular health within Hispanic populations, but a wealth of questions remain. For example, a 2022 analysis of 20 years of death certificates found consistently lower death rates for cardiovascular disease for Hispanic adults but a growing rate of stroke-related death for Hispanic men and older Hispanic adults. The research, published in the , also showed death rates for heart failure were increasing quickly among younger Hispanic adults. In fact, heart failure deaths among Hispanic men accelerated faster than they did among white men across all ages.

The COVID-19 pandemic also raised questions about the paradox when it became apparent that Hispanic adults were dying at higher rates than their white peers. But while COVID-19 cut life expectancy across races and ethnicities, Hispanic adults continue to live slightly longer than all other groups except Asian people.

The Hispanic paradox is "still a mystery," said Avilés-Santa, a former director of HCHS/SOL. Though the concept is controversial, "there is some truth to it. Life expectancy measurements are consistently longer for Hispanic than white people, especially for Hispanic or Latina women."

Knowledge gaps remain

Identification of the Hispanic paradox had other unintended consequences, Fernández-Rhodes said. It left the impression that there was less need to study cardiovascular health in Hispanic populations because they weren't dying from heart disease at the same rate as their white peers.

"In particular, they have been left behind by many genetic studies," said Fernández-Rhodes, whose own research at Penn State focuses on this area.

She's also concerned that large groups of Hispanic people are still being missed by researchers who use data from health insurance claims since this population has the highest uninsured rate in the U.S. "If we rely on data collected as part of clinical care – and not everyone has health insurance or has more barriers to care, such as not having someone who can translate for them or they can't pay the out-of-pocket expenses – this is a major limitation."

People who have insurance and regularly access the health care system "are people with higher socioeconomic status," Fernández-Rhodes said. "That means cardiovascular prevention and treatment data culled from these databanks may be biased."

Looking ahead

Rodríguez said more investigation is needed into how risk factors change over time and with subsequent generations, as well as more studies on tailoring interventions to individual Hispanic subgroups.

Hispanic populations remain among the fastest growing in the U.S., second only to Asian people. And, as with Asian populations, the diversity of subgroups changes over time.

"Solutions that might work for one population may not work for others," Rodríguez said.

The knowledge gained from HCHS/SOL about differences among subgroups should be applied to developing targeted interventions, Avilés-Santa said. "We need to not just look at the differences, but what they really mean. They open the door to many questions that could influence the field of precision medicine and others."

And while there is no shortage of questions, there also aren't enough researchers trying to answer them, Avilés-Santa said.

"We need more investigators who are daring to ask very important questions, who are daring to think outside the box and engage and honor and respect the Hispanic and Latino community," she said. "We need people who understand why these questions are important. I think the key players that are needed are people who are inspired to ask those questions."

Chief among those questions is how to prevent cardiovascular risk factors as early as childhood so that Hispanic people can lower their high rates of obesity, diabetes and other heart and stroke risk factors, Avilés-Santa said.

"If we are living longer than other groups, we may as well start preventing health problems earlier, so we can fully enjoy those extra years that we have."