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A cancer patient pushes his drip stand as he walks down the hallway of the Beijing Cancer Hospital on July 12, 2011.

The health problems that attract the world’s attention tend to be infectious diseases, like the respiratory illness COVID-19, which infected more than 160 million people around the world by May 2021. But some of the deadliest killers are no longer those that pass from person to person. A full 74 percent of the world’s deaths are the result of diseases such as cancer or diabetes that aren’t transmitted between people. These are called noncommunicable diseases (NCDs).

NCDs are a growing problem. In 2000, just four out of the top ten causes of death worldwide were noncommunicable. By 2019, that number had grown to seven out of ten.

Global Prevalence of Noncommunicable Diseases

When you look at graphs showing all NCDs lumped together, the trend becomes apparent: rates of NCDs are on the rise. But when you begin to parse the data, other trends emerge, and it’s possible to see how differently these diseases affect various communities.

To better understand the effects, let’s isolate the data on three of the deadliest NCDs: heart disease, dementia, and lung cancer. Each disease can show a different aspect of measuring, preventing, and treating NCDs.

Access to Health Care Matters

The most common type of heart disease is ischemic heart disease, which is related to problems with the arteries that bring blood to the heart. It’s the number one cause of death around the world and often caused by other conditions such as high blood pressure, high cholesterol, diabetes, and obesity. The disease can also result from lifestyle characteristics such as a lack of physical activity or smoking. It’s also shaped by something called the social determinants of health—factors like where people live, what they do for work, and how much they make. In the United States, systemic racism has influenced many of these factors, resulting in lower-quality health care for many people of color.

Health researchers use a measure called the Socio-Demographic Index (SDI) to evaluate a country’s level of development. Countries are given a grade that shows their level of development based on factors such as overall income and education. High SDI countries include the United States, the Czech Republic, and South Korea; low SDI countries include Chad, Nepal, and Papua New Guinea. The SDI is unique in that it doesn’t use overall health as a factor in its analysis. This exclusion makes the SDI a useful tool for health researchers because with health taken out of the picture, they can compare different countries and find out which factors help good health outcomes and which ones hinder them.

This is important to understand, for example, when looking at the mortality rates for heart disease. Separating the countries by their SDI rankings makes it clear that heart disease mortality rates are mostly decreasing in high SDI countries but have increased in the lower SDI countries.

Deaths From Ischemic Heart Disease

So what does this mean? People in wealthy countries tend to have better access to health care, which makes dealing with chronic diseases easier, so deaths from chronic diseases are decreasing there. People in wealthy countries are also more likely to have access to preventive health care and thus be aware of risk factors such as high blood pressure or cholesterol, which can be managed before they can cause heart disease.

Middle SDI countries, such as Brazil, and low-middle SDI countries, such as Myanmar, aren’t there yet. As these countries develop, their citizens become exposed to unhealthy lifestyle changes—think more sedentary office jobs or access to cheap fast-food options—that often accompany a country’s development. These lifestyle changes amplify the conditions that contribute to an increased risk of heart disease. And because access to health care tends to be more limited in these countries, the risk is magnified.

Age as a Challenge

Dementia is defined as the loss of or reduction in brain functions such as memory, decision-making, and even language. It occurs when healthy nerve cells in the brain deteriorate, lose connections with other brain cells, and die.

The average age for the onset of dementia in the United States is eighty-four years. Although dementia is estimated to cause 2.4 million deaths globally each year, mortality isn’t the most useful way of measuring dementia’s effects. A more interesting way to understand the impact of something like dementia is to look at Years Lived With Disability (YLDs).

As life expectancies increase around the world, the rates of YLDs are also rising for dementia in all countries.

YLDs for Alzheimer’s Disease and Other Dementias

So what does this mean? Simply put, it means people with dementia are receiving care for longer periods of time than they used to.

Longer lifespans are generally a good thing. However, longer lifespans also mean more people with dementia who need long-term care, which is harder to access in low SDI countries that tend to have less-developed health infrastructure.

Additionally, more than 60 percent of global dementia cases may go undetected, meaning dementia rates could be much higher than estimates reveal—and that those living with undiagnosed dementia aren’t getting the care they need.

The Effect of Gender

Lung cancer is the growth of malignant tumors in the lungs. It is the deadliest cancer, causing 1.8 million deaths in 2020. Although nonsmokers also get lung cancer, at least 80 percent of lung cancer deaths are associated with firsthand tobacco smoke.

Deaths From Tracheal, Bronchial, and Lung Cancer

Lung cancer death rates are much higher for men than for women due to higher smoking rates. Globally, around 35 percent of all men smoke, compared to about 6 percent of women.

As trends such as vaping emerge, new cases of lung cancer and other lung injuries could arise. While some of these cases have already been documented, others could take longer to appear. 

From Data to Your Day-to-Day Life

As lifespans extend, noncommunicable diseases pose a new kind of challenge to the progress made in global health. While NCDs are on the rise globally, data shows that not every disease affects everyone in the same way. People’s level of risk of heart disease, dementia, and lung cancer depends on who they are, where they live, and the choices they make.   

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