Depression is a pervasive and debilitating mental health disorder that affects more than 300 million people, making it the leading cause of disability worldwide. This disease arises from multifaceted interaction of social, psychological, and biological risk factors, including major life events, poor nutrition habits, and substance abuse. This week, we delve into the impact of serious illness and loneliness on depression. See last week’s post here.
Serious or Chronic Illness
Depression is both a result of intense suffering and a contributor to intense suffering, so it is not surprising that people with a serious medical condition are more likely to suffer from depression, and that the reverse is also true — those who have depression are at a higher risk of developing physical illnesses.
Diseases commonly associated with depression include cancer, coronary heart disease, diabetes, epilepsy, stroke, multiple sclerosis, HIV/AIDS, Alzheimer’s disease, and Parkinson’s disease. In “garden variety” cases, the onset of depressive symptoms may follow a medical diagnosis (i.e., illness-related anxiety and stress) but subside as the patient begins to accept the situation or the original condition is treated. In other instances, symptoms may persist, which then puts patients at a higher risk for other medical conditions. For example:
After diagnosis, 40% of cancer patients report developing significant symptoms of distress including intense worry, panic attacks, and depression.
People who have diabetes or rheumatoid arthritis are six times more likely to develop depression than those without.
Patients with major depression and bipolar disorder are dying prematurely due to medical illnesses when compared to patients without — evidence suggests up to five to 10 years earlier.
People with chronic medical conditions have been found to be two to three times more likely to suffer from depression compared with primary care patients of the same age and gender. For example, depression rates in primary care patients are between 5% and 10%, whereas the prevalence of depression in patients with coronary heart disease is between 15% and 23%.
There are a few theories around the mechanisms behind this bi-directional relationship. When chronic illness leads to depression, it may be because having to manage depressive symptoms makes it difficult for patients to care for their co-occurring illness, and they may neglect to seek care, take prescribed medication, eat well, and exercise. Other potential mechanisms are based on how some diseases — such as Parkinson’s disease and stroke — can physically change the brain, often in ways that play a direct role in depression.
When it comes to depression leading to chronic illness, scientists have found several changes in the way biological systems function in depressed patients, including increased inflammation, changes in heart rate and blood circulation, and abnormalities in stress hormones — all of which are precursors to physical and psychological diseases. These findings may be particularly relevant to older populations, given that 48% of individuals aged 65 and older live with chronic conditions and functional limitations (compared to 9% of those under 65).
Lack of Healthy Social Relationships
Humans are social creatures that need healthy social environments to thrive and to survive, which is why meaningful social relationships are essential for mental and physical well-being. When this need is not met, people may suffer from feelings of loneliness and isolation — both of which are prevalent social problems and major risk factors for depression. This problem is particularly prevalent in older populations. According to a poll conducted by Age UK, 2 million people over the age of 75 live alone in the UK, and approximately half say they go more than a month without speaking to friends, family, or acquaintances. In the US, an AARP-sponsored poll conducted by the University of Michigan found that nearly a third of senior are lonely.
Lonely people suffer from more depressive symptoms than those with healthy social lives, as they have been reported to be generally less happy, less satisfied, and more pessimistic. At any given time, up to 32% of people age 55 and over report feeling lonely, and anywhere from 5% to 7% report feeling significant or persistent loneliness. Research has also found that loneliness tends to be more pervasive in societies in which social media usage is high, and in most cases, has replaced more traditional, fulfilling forms of social interaction — suggesting that in-person social contact is essential for mental health. This is especially true for the most significant users of social media — adolescents and young adults — as they develop social skills that they will carry into adulthood.
A lack of healthy socialization adversely influences the brain and body in ways distinct enough to be measured over time. Studies tracking these effects have found that:
People who identify as lonely exhibit increased levels of stress hormones and higher blood pressure, which forces the heart muscle to work harder and subjects blood vessels to damage via blood flow turbulence.
Loneliness decreases the quality and effectiveness of sleep. Those who report being lonely tend to wake up more often during the night and spend less time truly sleeping than their non-lonely counterparts.
Feeling socially isolated activates neurobiological mechanisms that may take a toll on health and well-being in the long-term — such as larger morning rises in cortisol, increased levels of inflammation throughout the body, and altered gene expression.
Beyond all of the above, a lack of healthy relationships and/or loneliness has been linked to other psychiatric disorders including substance abuse, personality disorders, and Alzheimer’s disease, as well as other physical disorders including diabetes, coronary heart disease, and hypertension — all of which have also been associated with an increased risk for depression and can contribute to early morbidity and mortality. This has important implications for older populations. According to a poll conducted by Age UK, 2 million people over the age of 75 live alone in the UK, and approximately half say they go more than a month without speaking to friends, family, or acquaintances. In the United States, an AARP-sponsored poll conducted by the University of Michigan found that nearly a third of seniors are lonely.