Conditions Linked to Depression

It is common to hear people say, “I’m so depressed,” from time to time, usually as a way of expressing feelings of sadness. However, clinical depression is much more than having a bad day or feeling down. There are many symptoms of depressive disorders, which are legitimate mental health conditions, with sadness being just one of them.

Out of the eight depressive disorders listed in the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5), perhaps the most complicated is depression due to a medical condition. This is because a large body of research shows a two-way connection between mental and physical health.

According to studies, “depressive disorders are significantly more common in the medically ill compared to the general population.” Depression can make health problems worse by leaving a person feeling too drained to take care of themselves, follow treatment plans, or stay active. Additionally, having an illness can trigger depression, although the reason for this is unknown^[1][2].

This two-way connection, where physical and mental health impact each other, is called a bidirectional relationship. Essentially, it means that people with depression are more at risk of health issues, and people with health issues are more at risk of depression. Treating the medical condition and depression at the same time often helps to break the cycle^[2].

Understanding Depression Due to Medical Conditions

“Depressive disorder due to another medical condition” is a mental health disorder where someone experiences ongoing sadness or a noticeable loss of interest and enjoyment in things that used to bring them happiness. This is believed to be caused by the physical effects of a medical condition on the body^[3].

The DSM-5 states that depressive disorders share common emotional symptoms, such as persistent feelings of sadness, anxiety, emptiness, hopelessness, or irritability. Depression also often causes feelings of guilt and worthlessness, as well as difficulty concentrating. In severe cases, thoughts of suicide may occur, which is why it is imperative to seek treatment quickly^[2][4].

Physical symptoms of depression, including fatigue and changes in sleep or appetite, make it hard to practice self-care. Some people may also experience aches, pains, or digestive issues. What sets apart medically induced depression from other depressive disorders are differences in how long the symptoms last, when they occur, and the presence of an underlying medical condition^[2][4].

How Common is the Link Between Depression and Health Conditions?

Research has found that people with severe or moderately severe depression are at least 1.5 times more likely to develop at least 1 of 29 different health conditions. It has also been shown that the highest health risks associated with depression are for developing issues related to hormones, internal organs, muscles, bones, circulation, and blood^[5].

This reveals that depression puts people at risk of developing physical complications, and additionally, the study also demonstrated a link between medical conditions causing the development of depression. This two-way connection between mental and physical health is a somewhat modern discovery, and further research is needed to reveal its exact mechanisms^[5].

While scientists have not yet revealed precisely how the link between depression and other health conditions works, several factors are thought to play a role. These include^[6]:

• Issues with the stress response system
• Inflammation
• Genetics
• Nerve function
• Brain chemicals such as serotonin
• Omega-3 imbalances
• Gut bacteria
• Certain molecules

Many diseases cause depression, and conversely, depression causes many health conditions. Below, you will find what scientists currently know about medical conditions, the potential causes of depression, and vice versa.

Cardiovascular Conditions and Depression

Research shows cardiovascular disease and depression often go hand in hand. A study conducted across Hong Kong found that long-term depression significantly raises the risk of developing cardiovascular disease. Among the 11,651 patients with depression who participated in the study, more than 10% were diagnosed with heart-related conditions^[6].

Evidence also suggests that people with depression are more likely to develop high blood pressure, have a higher risk of stroke, and be more prone to heart disease. Any serious illness is tragic, and these findings highlight the importance of early diagnosis and treatment of depression to reduce further emotional and physical harm^[6][7].

Chronic Pain and Depression

Chronic pain from health problems like arthritis or fibromyalgia is a significant factor in causing depression. It is known that when both depression and chronic pain occur together, the conditions can make each other worse. However, how they are connected is still not fully understood, which makes them harder to treat^[8].

A recent study has found that changes in the brain caused by pain and depression are similar, suggesting they may share some common physical causes. It is thought that both conditions cause the brain pathways to rewire themselves and form new connections that influence how depression and pain are processed, worsening both conditions^[8].

Endocrine Disorders and Depression

Endocrine disorders, like thyroid conditions, problems with adrenal glands, or diabetes, are linked to depression. It has been found that issues with specific hormone systems in the body, like the HPT and HPA axes, can lead to depression. The HPT and HPA axes control hormone production, which can affect a person’s mood when imbalanced^[9].

The HPT axis is related to the thyroid and affects a number of thyroid conditions, such as underactive or overactive thyroid. The thyroid is a gland that helps control energy levels, metabolism, and mood, and if it is not working correctly, it can lead to fatigue, weight changes, and mood issues like depression^[9].

The HPA axis involves the adrenal glands controlling the body’s stress response. This includes the production of cortisol, a hormone that helps regulate blood sugar levels and mood. In people with diabetes (particularly type 2), the HPA system is out of balance, leading to anxiety, fatigue, and depression.

Neurological Conditions and Depression

Research has shown that the chances of having depression are significantly higher in people with neurological conditions compared to the general population. Among these conditions, migraine, traumatic brain injury, stroke, dystonia, and epilepsy are associated with the strongest links to depression^[10].

Depression is also common for people with Alzheimer’s disease or dementia, multiple sclerosis, Parkinson’s disease, and spina bifida. The connection is thought to be the result of a few factors. These include changes in brain makeup, the stress of living with a neurological condition, and the physical impact of these conditions on daily functioning^[10].

Respiratory Conditions and Depression

Scientific evidence to support the link between depression and respiratory conditions is limited. That said, one study has found that people with major depression are 2.4 times more likely to develop asthma, and those with moderate depression are 2.6 times more likely to develop chronic obstructive pulmonary disease (COPD) compared to those without depression^[11].

On the other hand, some studies suggest the connection between respiratory conditions and mental health symptoms, like depression, is only weakly related. Whatever the case may be, the connection between depression and other medical conditions has been proven, and scientists are working on finding out more^[12].

Gastrointestinal Disorders and Depression

As scientists learn more about the mind-body link, the connection between the brain and the digestive system has become more widely studied, and (like other medical conditions connected to depression) gut health has been found to have a two-way connection with mental health.

One study found that people with gastrointestinal (GI) symptoms were nearly five times more likely to experience severe depression compared to those without GI symptoms. Two of the most common gastrointestinal disorders that connect with mental health problems are inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS)^[13].

Interestingly, research has shown that a history (or current experience) of abuse or trauma is frequently linked to GI disorders. The connection between abuse and GI illness is thought to be related to stress affecting the brain and gut, leading to immune system changes and issues with the central nervous system’s ability to manage signals from the body^[14].

Cancer and Depression

Depression is common in cancer patients, affecting over 10% of people with cancer. While feelings of fear, disappointment, and sadness are a natural response to a cancer diagnosis, significant distress and low mood can sometimes overwhelm a patient’s ability to cope, leading to major depressive disorder. ^[15]

Depression worsens the quality of life and sadly increases the risk of death in cancer patients. Research shows even mild depression can raise a person’s mortality risk by 25%, while major depression may increase it by up to 39%. Cancer patients with depression also face a higher risk of suicide compared to the general population^[15].

For this reason, it is essential to identify depression in cancer patients and seek treatment as soon as possible. Depending on the nature of the cancer diagnosis, different options are available. A little later on, you will find more information on treating depression due to a medical condition.

Diagnosing Depression in the Context of Medical Conditions

It is relatively easy to pinpoint symptoms of depression, such as persistent sadness and a loss of interest in activities that used to bring joy. However, diagnosing depression linked to a medical condition can be difficult. This is because depression can lead to physical illness, and physical illness can lead to depression, so doctors need to determine which came first.

According to the DSM-5, to make the diagnosis, health professionals need to confirm the presence of a medical condition, and that it is directly linked to mood changes through physical mechanisms. This requires a detailed evaluation of many factors. Criteria that help make the connection include^[4]:

• Symptoms of depression that interfere with day-to-day functioning
• A clear timeline showing that the mood changes began or worsened alongside the medical condition
• Evidence from scientific studies showing that specific medical conditions can directly lead to mood symptoms
• Unusual features that don’t match typical depressive disorders, like starting at an uncommon age or not having a family history of depression
• When other causes for depression, such as medication side effects, alternative mental health issues, or delirium, are eliminated from the equation

Treating Depression Due to a Medical Condition

There is hope for those with serious medical conditions because depression is treatable. Treatment options include therapy, medication, or ideally both. A collaborative care approach, where mental and physical health providers work together in one location, has been shown to enhance overall health in people suffering from co-morbid depression^[2].

Psychiatrists, psychologists, and doctors can help create a treatment plan tailored to a specific medical condition, ensuring no harmful interactions between medications. There is evidence to suggest that alternatives to medication, like psychotherapy, brain stimulation therapy, or light therapy, are also effective^[2].

Finding the right treatment may take time, but significant improvement in mental and physical health is possible. If you or your loved one is struggling with depression due to a medical condition, it’s a good idea to talk to a doctor for guidance and referrals to qualified mental health professionals.

Treating Cardiovascular Conditions and Depression

Treating depression alongside heart disease often involves adding antidepressants to heart health treatments. Traditional Chinese medicine (TCM) also shows promise in managing both conditions^[6].

This is because it targets multiple health issues while causing fewer side effects. TCM may help by reducing inflammation and boosting brain chemicals linked to mood improvement^[6].

Treating Chronic Pain and Depression

Treating depression alongside chronic pain often involves a combination of medication, therapy, and lifestyle interventions. Medication targeting specific brain signal systems can help relieve both pain and depression, though their use requires careful monitoring due to potential side effects^[8].

Therapy, such as cognitive behavioral therapy, plays a crucial role in addressing the emotional and psychological factors contributing to pain and depression. Emerging treatments, including those targeting specific protein (BDNF) and dopamine receptors, offer promising options due to their ability to rewire neural connections^[8].

Treating Endocrine Disorders and Depression

There is emerging research suggesting that thyroid hormones can play an essential role in treating depression. One hormone, LT3, can speed up and improve the effects of antidepressants, especially for people who don’t respond to typical treatments. Another hormone, LT4, has been shown to help manage hard-to-treat (also known as intractable) depression^[16].

Brain scans have shown that LT4 helps by improving activity in areas of the brain involved in mood regulation. While it’s well-known that depression linked to thyroid conditions usually improves once thyroid levels are normalized, the use of thyroid hormones alone (without standard psychiatric medications) has been studied very little^[16].

Treating Neurological Conditions and Depression

A study conducted in 2023 states that treating depression in neurological diseases often involves a mix of approaches, such as medication, cognitive-behavioral therapy (CBT), physical activity/exercise-based interventions, or even electroconvulsive therapy (ECT). Attention should be given to less common symptoms, like cognitive decline, which may also indicate depression^[17]. These symptoms may require independent evaluation to rule out other conditions, which is vital before beginning treatment.

While the effectiveness of antidepressants is well-established for major depression, their success in milder cases linked to conditions like Alzheimer’s, Parkinson’s, or strokes is less certain. Alongside medication, treatments like therapy are essential for managing moderate to severe depression^[17].

Treating Respiratory Conditions and Depression

A recent study reviewed the effects of various psychological and lifestyle treatments on depression and anxiety in people with COPD. It found treatments combining psychological methods with exercise (known as multicomponent pulmonary rehabilitation) were the most effective in reducing both depression and anxiety^[18].

Like treatment suggestions for other medical conditions with depression, interventions like cognitive behavioral therapy, relaxation techniques, and self-management education were found to have an impact. When treatments included both psychological techniques and exercise, the improvements in symptoms were more significant^[18].

Treating Gastrointestinal Disorders and Depression

Advances in understanding the mind-gut connection have led to new approaches in managing mental health and digestive issues, with treatments like psychobiotics showing promise in improving both gut and mental health^[19].

Psychobiotics refer to a class of probiotics, which are live microorganisms believed to positively affect mental health by influencing the gut-brain axis. One study found that after using the probiotic for two months, depression symptoms improved significantly^[19].

Treating Cancer and Depression

Depression in cancer patients can be treated with antidepressants, though some may interfere with specific cancer treatments, and others may offer faster relief for terminal patients. Careful monitoring is essential to manage drug interactions^[15].

Relaxation techniques, cognitive-behavioral therapy (CBT), psychoeducation, and exercise therapy can also reduce depression in cancer sufferers and improve their quality of life. For more information on treating cancer and depression^[15].

Key Takeaways

Studies show that depressive disorders are more common in those with medical illnesses than in the general population. Depression can worsen health problems by leaving individuals too exhausted to care for themselves, follow treatments, or stay active. Conversely, having a health condition can trigger depression, though the exact reason is unclear.

This relationship, where physical and mental health affect each other, is a growing body of research, and scientists are uncovering more and more potential causes. It has been found that treating both chronic illness and depression together can help break this cycle, although treatment varies depending on the condition.

If you or a loved one are suffering from medical conditions that cause depression, it is essential to seek treatment as soon as possible.