6 Biological Causes of Depression Symptoms

Imagine you’re experiencing chest pains. You aren’t sure of the underlying cause, but they’re starting to interfere with your daily life. You visit a cardiologist, and the diagnosis finally arrives: chest pains. Would you be satisfied with that answer?

This might sound ludicrous, but similar situations happen every day in the realm of mental health. According to the World Health Organization, an estimated 5% of the global population has depression. But when they seek help, instead of being thoroughly tested to find the root of their mental health problems, they’re too often told what they already know: They have depression.

Getting diagnosed with clinical depression is simply not good enough. Instead, it’s crucial to determine what exactly is causing it, so you can get the most effective treatment plan.

In this blog, you’ll discover 6 common depression causes and targeted treatment tips to help you feel better faster.

Getting diagnosed with clinical depression is simply not good enough. Instead, it’s crucial to determine what exactly is causing it, so you can get the most effective treatment plan. Click To Tweet


It’s important to think of depression as a symptom. Unless you know what’s causing your depression symptoms, you won’t get the targeted treatment you need.

Furthermore, treatment should never consist only of antidepressant medications. One randomized controlled trial reported that more than half of those who report depression don’t experience relief from their symptoms simply by taking prescription antidepressants.

And a significant number of people—about 1 in 3—don’t achieve remission even after four courses of antidepressant treatment. Treatment-resistant depression is all too common.

These are just a few reasons why it’s important for mental health professionals and patients alike to start seeing depression as a symptom, not a diagnosis.


If failing to properly diagnose and treat clinical depression is a too-common phenomenon, how can practitioners and patients improve?

First, avoid assuming that depression is a single or straightforward disorder. Brain-imaging studies using SPECT scans at Amen Clinics clearly show that there are several types of depression.

With so many possible contributing factors and causes of depression, it’s important to take a holistic view of each individual, as well as their environment. Depression is not only psychological. It can have biological roots, which are often overlooked by both traditional psychiatrists and mental health professionals.

Let’s review some of the most common biological risk factors for depression—and how to address them:

  1. Head injuries

Mild traumatic brain injuries (mTBIs) can interfere with your mental health, even if you never blacked out or were diagnosed with a concussion. A 2020 study published in Frontiers in Neurology found that people who receive a mild head injury are more than 3 times more likely to have depression, compared to those without these injuries.

Using SPECT brain imaging technology, which measures blood flow and activity, Amen Clinics has detected previous head trauma in roughly 40% of patients. Moreover, these clients are often completely unaware of the injury. So-called minor incidents, such as falling off a bike or being in a car accident, can cause a TBI—thus raising the risk for depression.

Treatment tips: When a TBI is influencing the onset of clinical depression, it’s important to heal the underlying injury.

Hyperbaric oxygen therapy (HBOT) may help accelerate the healing of brain trauma. One study reported that a single HBOT session helped increase blood flow in the brains of individuals with a mild to moderate TBI.

  1. Low thyroid levels

According to a 2022 review, hypothyroidism (an underactive thyroid) is a common underlying issue for those with treatment-resistant depression. That’s not surprising, since low thyroid activity impacts brain function and creates a sluggish feeling.

In fact, research has shown for decades that hypothyroidism is linked to depression. On brain SPECT scans, low thyroid levels tend to coincide with overall low activity in the brain—also seen in patients who complain of symptoms like brain fog and depression.

Treatment tips: Check your thyroid levels and optimize them if necessary. Natural strategies can help balance thyroid function, which also boosts mood.

Cut sugar out of your diet and consume more foods with high selenium levels, such as tuna, turkey, and Brazil nuts. Take a vitamin B-12 supplement for extra support.

  1. Inflammation

Unfortunately, many modern lifestyle choices—eating processed foods, drinking alcohol, or enduring constant stress—can lead to chronic inflammation in the body. Inflammation is a known risk factor for depression.

Inflammation has been called a “silent killer,” because it’s often undetected but leads to life-threatening physical ailments. Numerous studies have also linked high levels of inflammation with a long list of mental health issues, including mood disorders like depression and bipolar disorder, anxiety disorders, and more.

Treatment tips: Poor gut health is strongly associated with elevated levels of inflammation in the body. Take care of your gut by adding a high-quality probiotic supplement to your daily routine.

Certain nutritional supplements with anti-inflammatory properties—including omega-3 fatty acids and curcumin—have been found to decrease depression symptoms in those with chronic inflammation.

  1. Mold exposure

A home or workplace with toxic mold may trigger a host of issues, from depressive symptoms to memory loss and sleep disorders. And one large public health study, conducted among almost 6,000 adults by Brown University, found connections between depression and living in damp, moldy environments.

Meanwhile, humans are exposed to toxic elements every day that can damage the body and brain. Chemicals, fumes, pesticides, and other products may contribute to mood swings and psychological distress. Unfortunately, such cases are prone to misdiagnosis.

Treatment tips: Fix the source of the problem to promote better health. Stay away from moldy environments, install air purifiers, and take steps to eliminate mold. Discourage mold activity by preventing water leaks and fixing plumbing issues whenever they occur.

If mold has already caused toxicity in the brain, numerous treatments are available. These may include medications, binding agents, metabolic support supplements, and more.

  1. COVID

Years after the first COVID-19 outbreaks, experts are still examining its widespread effects. One important finding from Amen Clinics’ brain-imaging work is that post-COVID brains can show increased activity in the limbic system, also known as the brain’s emotional center. This pattern is associated with depression.

Many people remain unaware that infections like COVID are a major cause of mental health disorders, including depression. But a 2021 study in JAMA Network Open noted that, after being infected with COVID, more than half (52.4%) of patients met the criteria for major depressive disorder just several months later.

Treatment tips: To help ward off infections, strengthen your immune system. Consume immune-boosting foods like garlic and onion, plus nutritional supplements like vitamin D, and therapeutic mushrooms like lion’s mane and reishi.

In cases of long COVID, a holistic brain-body approach, from lifestyle changes to psychological strategies, can be effective in reducing symptoms. Meanwhile, studies have discovered potential in other treatments, such as infrared sauna therapy and HBOT, for accelerating post-COVID healing.

  1. Heart disease

The link between heart disease and depression is bidirectional: People with depression are more likely to develop heart disease and are more likely to die following a heart attack than those without depression. But research also shows that depression is 3 times more common in people who have already had a heart attack.

Treatment tips: Many Americans are unaware that heart disease is the leading cause of death in the U.S.—despite that being the case for over 100 years! If you have heart disease, be vigilant about monitoring your mental health.

If you don’t have heart disease, take steps now to prevent cardiovascular issues. Stick to a healthy diet and physical activity routine. Avoid smoking and drinking alcohol. Join a support group to create strong social bonds, which can have a positive impact on depression symptoms.


With so many possible causes and contributing factors, depression should never be viewed as a simple, straightforward mental health diagnosis. However, comprehensive testing, including functional brain scans such as SPECT, can help determine its root causes.

Pinpointing and then addressing these underlying issues are the first steps toward truly healing. With the proper diagnosis and treatment plan, depression transforms from a potentially debilitating disorder to a symptom that can be minimized and managed in healthy, holistic ways.

Depression and other mental health issues can’t wait. At Amen Clinics, we’re here for you. We offer in-clinic brain scanning and appointments, as well as mental telehealth, clinical evaluations, and therapy for adults, teens, children, and couples. Find out more by speaking to a specialist today at 888-288-9834 or visit our contact page here.

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