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9 Conditions That Mimic Depression But Aren’t

Common symptoms like fatigue, irritability or trouble sleeping may make people appear depressed

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If you or a loved one feels sad or excessively tired or is having sleep problems, you may assume depression is to blame. But experts say many conditions mimic depression — and doctors can get it wrong.

In fact, about 26 to 45 percent of patients referred for “depression” do not meet the diagnostic criteria for the illness, according to an article in Current Psychiatry. One analysis of 118 studies found that general practitioners correctly identified depression in only 47 percent of cases, and that they often diagnose it in people who don’t have it.

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The challenge for physicians is that there is no single, definitive test for depression, says psychiatrist Jonathan E. Alpert, M.D., chair of the Council on Research at the American Psychiatric Association.

“We can’t send someone for a blood test or an MRI to make the diagnosis of depression,” says Alpert, who is also chair of psychiatry and behavioral sciences at Montefiore Medical Center and the Albert Einstein College of Medicine.

Instead, to get a depression diagnosis, guidelines call for patients to have at least five of nine specific symptoms (see box) for more than two weeks. Health care providers should also rule out other conditions, Alpert says.

Experts say it’s especially important to consider other possible diagnoses in older adults. While it’s certainly true that people over 50 can experience depression, most people first experience the condition in early life. In addition, older adults are more likely to have atypical symptoms or other conditions that can cause depression or be mistaken for it.

“It’s often challenging to diagnose depression because the symptoms may overlap with chronic medical conditions, early dementia, hearing and vision loss, and medication side effects,” says Meredith Gilliam, M.D., a geriatrician and medical director of the University of North Carolina Geriatrics Clinic in Chapel Hill. “It takes time and patience for family and clinicians to work through what is really going on.”

The biggest danger of a misdiagnosis is that you might have a serious condition — cancer or dementia, for example — that would benefit from early treatment. 

Here are some of the most common conditions that can mimic or cause depression:

1. A thyroid disorder

Thyroid issues are a common disorder that can be mistaken for depression, says Joseph Lai, a general practitioner at Novant Health in Charlotte, North Carolina.

The thyroid is a butterfly-shaped gland that regulates important body functions, like your heart rate and energy level. The risk of a thyroid problem increases as you age.

“The thyroid is one of those little organs that has its fingers in everything,” Lai says. “If not working properly, it can definitely mimic depression.”

A thyroid problem can cause fatigue, feelings of sadness and irritability — all symptoms that overlap with depression.

However, weight gain or swelling, intolerance to cold and extreme fatigue can point to an underactive thyroid rather than depression, Alpert says. Someone who is depressed may feel unmotivated or uninterested in doing things, while someone with an underactive thyroid may feel like they just don’t have the energy, he says.

Overactive parathyroid glands, a different thyroid disorder that creates high calcium levels in the blood, can also cause depression-like symptoms.

About 20 million Americans have some form of thyroid disease, and as many as 60 percent don’t know it, according to the American Thyroid Association. If you suspect a thyroid problem, consider asking a health care professional to test for it.

2. Diabetes

About 38 million people in the United States have diabetes, including an estimated 25 percent of adults over age 65. Remarkably, 1 in 5 people with diabetes don’t know they have it, the Centers for Disease Control and Prevention (CDC) says.

Diabetes can make you feel tired and irritable and contribute to unexplained weight loss — all potential symptoms of depression.

One clue that diabetes may be causing your symptoms is if you also experience excessive thirst or hunger, Alpert says. Frequent urination is another classic diabetes symptom. A simple blood glucose test can determine if you have the disease.


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3. Vitamin deficiency

Sometimes, a nutrient deficiency can cause depression-like symptoms. Two common nutrients that many older adults don’t get enough of are vitamin D and vitamin B12.

About 35 percent of U.S. adults don’t get enough vitamin D, according to the Cleveland Clinic. Symptoms of a deficiency include a lack of energy, pain and weakness that can resemble depression, Lai says. The easiest way to get more vitamin D is to spend time outside, because your body turns sunlight into vitamin D.

Vitamin B12 plays an essential role in nerve function, and a shortfall is associated with depression, dementia and decreased cognitive function.

Older adults are at greater risk of vitamin deficiencies, Lai says, so he always checks nutrient levels before diagnosing depression. If you have a shortfall, your health care provider may recommend a supplement.

4. Cancer

Many symptoms attributed to depression — loss of appetite, weight loss and fatigue, for example — can also be early signs of cancer, Alpert says.

In addition, the latest research shows many cancer patients experience depression even before their cancer is diagnosed, leading researchers to consider depression as a possible early signal that a disease process is at work in the body. 

For example, in a 2016 Swedish study that included 300,000 cancer patients and more than 3 million cancer-free patients, researchers found that the cancer patients were more likely to be diagnosed with psychiatric disorders in the 10 months before their cancer was diagnosed compared to those who were cancer-free.

The link between depression and cancer is particularly strong with pancreatic cancer, Alpert says. Two review studies have found that between 33 percent and 45 percent of pancreatic cancer patients reported psychiatric symptoms before their medical symptoms.

Symptoms of Depression

Talk to your doctor if you have any of the following symptoms of depression:

  1. Feeling sad or having a depressed mood
  2. Loss of interest or pleasure in activities once enjoyed
  3. Changes in appetite/weight loss or gain unrelated to dieting
  4. Trouble sleeping or sleeping too much
  5. Loss of energy or increased fatigue
  6. Increase in purposeless physical activity (inability to sit still, pacing, hand-wringing) or slowed movements or speech (these actions must be severe enough to be observable by others)
  7. Feeling worthless or guilty
  8. Difficulty thinking, concentrating or making decisions
  9. Thoughts of death or suicide

5. Dementia

The early signs of dementia include detachment and a loss of interest in activities, which can look a lot like depression.

“I can think of situations where a person was presumed to have depression because they stopped going to activities like dinner with friends, didn't speak much in group conversations, or lost interest in watching movies or other activities that require concentration,” Gilliam says.

Over time, she says, it would become apparent that dementia was the culprit as the person’s memory and processing problems became more evident.

The biggest way to distinguish between the two conditions is the forgetfulness that comes with dementia, experts say. Someone with depression also typically won’t get disoriented or lost in familiar places the way someone with dementia will.

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6. Parkinson’s disease

Parkinson’s disease causes chemical changes in the brain, such as the loss of dopamine neurons, that lead to a loss of motivation, engagement and interest, Alpert says. “That overlaps very much with what we see in depression,” he says.

Sometimes, depression and apathy appear in Parkinson’s patients even before motor symptoms, such as stiffness and tremors, become prominent, he says.

Parkinson’s is usually diagnosed through a neurological exam. Providers will look for tremors, stiffness, rigidity, slowness of movement, balance problems and a loss of facial expression.

People who are diagnosed with Parkinson’s are at high risk of depression. Studies show as many as half of Parkinson’s patients will experience some form of depression.

7. Anemia

If you have anemia, you don’t have enough healthy red blood cells to deliver oxygen to your body tissues. You may feel tired and weak and have trouble concentrating, problems that are also symptoms of depression.

Your risk of anemia increases with age, and it is especially prevalent in people over age 65, according to the CDC. Iron deficiency is the most common cause of anemia, but it can also be caused by bleeding in the intestinal tract, a malignancy or a folic acid or B12 deficiency. 

In addition to weakness and fatigue, anemia may cause cold hands and feet, dizziness and shortness of breath — symptoms not associated with depression. Anemia can be detected through a simple blood test. 

8. Medication side effects

More than 200 drugs have been linked to feelings of sadness, depression and suicidal thoughts. In fact, about a third of Americans are taking a prescription medication that could potentially cause depression or increase suicide risk, according to a study published in the journal JAMA.

Common ones include steroids, sleep or antianxiety medications, anti-seizure drugs and opioid pain medications.

When someone has depression symptoms, “we’re always wondering, did this coincide with starting a new medication,” Alpert says, adding that it can take weeks or months after you start a new medication for a side effect like depression to emerge.

If you suspect your medication is causing your low mood, it’s important not to stop the medication on your own. Instead, talk to your health care provider about your concerns, Alpert says. If the medication is important for your condition, he or she might want to keep you on the medication and treat your depression with an antidepressant.

9. Prolonged grief

It’s normal to grieve after losing a loved one. However, if you experience intense grief that hinders your normal routine for more than a year after the loss, what you think is depression may actually be prolonged grief disorder.

Prolonged grief disorder is a relatively new psychiatric diagnosis characterized by constant yearning for someone who has died and difficulty accepting the reality of the loss. 

Although prolonged grief may look like depression, Alpert says, there are specific, evidence-based psychotherapies that can target it and help you feel like yourself again.

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