Chronic disease is a scourge of older age. About 85% of people ages 60 or older have at least one such condition, and 60% have at least two.
The numbers can climb even higher; some diseases seem to go hand in hand, so having one automatically increases your risk for developing another.
A vicious cycle
Some of the most common chronic conditions are very closely related, such as obesity, high blood pressure, type 2 diabetes, high cholesterol, and heart disease. Many of these conditions are risk factors for each other, creating a domino effect: If one is not controlled, it raises the risk of developing another.
For example, obesity can lead to type 2 diabetes or high blood pressure; those conditions damage blood vessel walls; that damage makes blood vessels more susceptible to cholesterol deposits (especially if you have high blood levels of cholesterol); plaque buildup on the blood vessel walls leads to blood vessel stiffness, narrowing, and blockages (atherosclerosis); and atherosclerosis leads to cardiovascular diseases such as heart attack or stroke. Other related problems include:
- Vision loss (from damaged blood vessels in the eyes).
- Erectile dysfunction in men.
- Narrowed blood vessels in the extremities (peripheral artery disease), which can result in amputations.
- Chronic kidney disease, which can lead to kidney failure.
Even if risk factors are well controlled, a study published online Nov. 20, 2020, in Circulation suggested that diabetes still raises the risk for cardiovascular disease by 21%.
"The reason for this excess cardiovascular risk isn't well understood, but we often don't diagnose diabetes until some time after it starts, so we don't have the opportunity to control risk factors from the beginning. Also, we only have a small number of patients with all of those risk factors controlled," says Dr. David M. Nathan, director of the Diabetes Center and Clinical Research Center at Massachusetts General Hospital.
Many other chronic conditions are linked to each other. One example: autoimmune conditions, in which your immune system mistakenly attacks your own body's tissues as if they were a foreign invader. These conditions include type 1 diabetes (an attack on cells that make insulin, the hormone that helps cells extract sugar from the blood), Hashimoto's disease (an attack on the thyroid gland), and rheumatoid arthritis (an attack on the linings of the joints).
"Autoimmune diseases tend to run in clusters. Once you have one, you're more vulnerable to others because your immune system has a basic defect," Dr. Nathan says. "For example, if you have Hashimoto's disease, you have a 14% chance of developing another autoimmune disease, far greater than people who don't have any autoimmune disease."
Here are some other examples of associations between chronic conditions.
Hearing loss and cognitive decline. "Hearing loss can decrease the ability to communicate. This can impair a person's social interactions, which may increase the risk of developing dementia. Some experts believe hearing loss might be changing the brain's structure, making it more susceptible to dementia," says Dr. Elliott Kozin, an otologist (hearing specialist) at Harvard-affiliated Massachusetts Eye and Ear.
Obesity and joint problems. In addition to obesity's role in cardiovascular disease and type 2 diabetes, obesity also puts a strain on your joints, hastening the wearing-away of cartilage (osteoarthritis).
Obstructive sleep apnea and high blood pressure. Obstructive sleep apnea is characterized by temporary pauses in breathing during sleep (apneas), which occur when the tongue or throat tissue blocks the airway. "During each apnea, oxygen levels drop and put stress on the heart. The apnea ends with a brief arousal from sleep, accompanied by a surge in stress hormones and an increase in heart rate and blood pressure. Over time, this permanently changes blood vessels and increases blood pressure," explains says Dr. Lawrence Epstein, a sleep specialist with Harvard-affiliated Brigham and Women's Hospital.
What you should do
If you have any chronic conditions, it's important to ask your doctor about the risk for associated diseases.
In some cases, you should get a health screening. "People with sleep apnea should be screened for high blood pressure. Likewise, doctors should ask people with high blood pressure questions to determine if they might have sleep apnea," Dr. Epstein says. If you have high blood pressure and your doctor hasn't asked you about sleep symptoms, you should bring it up.
"For type 1 or 2 diabetes, we'll check blood pressure, kidney function, and cholesterol levels," Dr. Nathan says. "You'll also need regular checks of your feet and eyes to detect early problems and prevent severe ones."
In other cases, additional screening isn't automatic. "Hearing loss diagnosed on routine hearing tests does not automatically warrant formal testing for dementia. However, if someone has developed new cognitive problems, then this type of testing should absolutely be explored," Dr. Kozin advises.
And in all cases, ask what you can do to reduce your risk for other chronic conditions. "You don't want to be surprised by complications," says Dr. Nathan, "especially if they could have been treated or prevented."