Medically reviewed by Vicky Davis, FNP
Written by Our Editorial Team
Last updated 6/19/2022
Depression is a serious mood disorder that can affect people of all ages and backgrounds. It’s particularly common in women -- in fact, data from the 2020 National Survey on Drug Use and Health shows that 10.5 percent of US women had depressive symptoms in the prior year.
Most of the time, your mental health provider will diagnose depression by talking to you about your symptoms, performing a physical exam and, if appropriate, taking a blood sample to use for lab analysis.
However, new technologies are helping mental health providers to diagnose depression more accurately, and often prescribe more effective forms of treatment.
One of these technologies is positron emission tomography (PET) scanning. A PET scan is a type of imaging test that can compare brain activity, including in areas of the brain that can be affected by mental health disorders such as major depression.
When a PET scan, magnetic resonance imaging (MRI) scan or related imaging technology is used to assess brain activity in people with depression, it may be referred to as a depression brain scan.
Below, we’ve explained how this type of scanning works, as well as the information that it may be able to provide to mental health experts about the effects of depression on brain function.
We’ve also explained how brain scans may help with the accurate diagnosis and treatment of depression and other mental disorders, as well as the current state of research into scanning and imaging technologies for depression.
Depression is a common mood disorder that can have a significant impact on your wellbeing, including many aspects of your daily life.
Common signs and symptoms of depression in women include a persistent negative or empty mood, irritability with other people, a lack of interest in your hobbies and relationships, as well as a persistent feeling that your situation is hopeless or that you’re personally guilty.
These symptoms aren’t simply the result of a bad mood. Instead, experts believe that many of the symptoms of depression are related to changes in your brain caused by low levels of vital, naturally-occurring chemicals called neurotransmitters.
Neurotransmitters are natural chemicals that allow neurons -- nerve cells located in your brain and throughout your body -- to communicate.
Researchers have identified several neurotransmitters that are involved in the development of depression, including serotonin, norepinephrine, dopamine, glutamate and a neurotransmitter modulator referred to as brain-derived neurotrophic factor (BDNF).
These neurotransmitters have a significant effect on brain activity. For example, serotonin is a vital brain neurotransmitter that helps to regulate your mood, happiness, anxiety and stimulate the areas of your brain that control sleep and waking.
Norepinephrine is involved in stimulating areas of the brain responsible for attention, focus and memory. It also has a range of effects throughout the rest of your body, such as breaking down fat and increasing your heart rate.
In addition to affecting neurotransmitter levels -- or, as a result of its effects on neurotransmitter levels -- depression can affect the function of your brain.
For example, the prefrontal cortex -- a region at the front of your brain that’s responsible for your ability to express your personality, make decisions and plan complex mental behavior -- is often impaired in people with major depressive disorder.
Many medications for depression, including selective serotonin reuptake inhibitors (SSRIs) are designed to increase levels of neurotransmitters and change brain activity in a way that makes the core symptoms of depression less severe.
The term “brain scan” refers to several different imaging technologies that are used to examine the brain and assess certain aspects of brain function.
These include positron emission tomography (PET) scans, magnetic resonance imaging (MRI) scans and computed tomography (CT) scans.
Before we get into the specifics of each depression brain scan technique, it’s important to touch on why brain scanning may eventually become a key part of the clinical diagnosis of depression and effective treatment.
Currently, most people are diagnosed with depression following a psychiatric evaluation. This is a process that involves a depression screening -- a series of questions and tests to determine if you show clear, persistent depression symptoms.
As part of a depression test, your healthcare provider may ask you about the way you feel, your general moods, your sleep habits, daily activities and other aspects of your life.
They may also ask you to provide a blood sample. This allows them to identify if you have any physical health issues, such as thyroid disease or anemia, that can affect your quality of life and contribute to depression.
This assessment is typically performed by a psychiatrist. In fact, we provide an online psychiatry service, allowing you to connect with a provider and undergo an evaluation from the privacy and comfort of your own home.
If you meet the diagnostic criteria for depression, your healthcare provider may suggest that you take part in psychotherapy and use medication to treat your symptoms.
Psychotherapy and medication are effective. However, they don’t work right away for everyone with depression, and it’s far from uncommon for people to try several antidepressants or types of therapy before they find the ones that work best for their specific clinical symptoms.
In fact, more than 60 percent of people diagnosed with depression fail to completely respond to their first form of treatment.
Some people also have treatment-resistant depression -- a form of depression that may not get better with conventional treatments.
Treating this type of depression often requires a complex optimization of different medications, forms of therapy and even electroconvulsive therapy -- a form of treatment that involves direct brain stimulation using small electric currents.
The idea behind depression brain scans is that modern brain imaging technology could make it possible for mental health providers to identify the specific depression treatments that are most likely to produce a positive response for depressed people.
Put simply, by scanning the brain instead of relying on discussion and blood tests, experts may be able to reach a more effective diagnosis and treat depression faster.
Although brain scans aren’t used in current treatments for depression, imaging studies suggest that they may soon be of value for some types of depression.
For example, a study published in the journal JAMA Psychiatry in 2013 employed neuroimaging to identify biomarkers for depression treatment response.
The researchers studied 65 patients with depression, first by performing brain imaging, and then by assigning the study participants to complete 12 weeks of treatment with either the medication escitalopram (the generic form of Lexapro®) or cognitive behavior therapy (CBT).
Using the data collected from brain imaging, the researchers were able to identify correlations between activity in certain brain regions and treatment outcomes. A total of six different limbic and cortical regions were identified as part of the imaging process and study.
The researchers noted that further research of this type may help to guide initial treatments for people with certain types and subtypes of depression. Additionally, there may be other benefits brain scans can provide that aren’t yet fully understood.
Currently, there are several brain imaging techniques and technologies that may be useful for diagnosing and treating depression:
Positron emission tomography (PET) scan. This type of imagine test uses a small amount of a radioactive substance, referred to as a tracer, to detect blood flow to and from certain areas of the body, including the brain.
Magnetic resonance imaging (MRI) scan. This type of imaging test uses radio waves and magnets to create an image of the brain or other areas of your body. Some forms of MRI scan require the use of contrast dye to more clearly visualize certain areas.
Computed tomography (CT) scan. This type of scan uses x-rays to create pictures of your brain, skull, eye sockets and sinuses. It can detect brain defects and injuries, and may help to identify the cause of certain mood or behavioral disorders.
Currently, the approach of using a brain scan for depression diagnosis and treatment is still in the early phases of development. Trials are underway and researchers around the world have started to investigate it as a potential option for treating certain types of depression.
However, brain scanning isn’t yet a reliable approach for diagnosing depression or identifying a potentially effective form of treatment.
One reason for this is that we simply don’t have enough data yet to reach any firm conclusions about what brain imaging results truly mean. Many current studies are small in scale, and data is limited in both quantity and quality.
As a recent article in the journal Nature put it, brain-wide association studies, or BWAS, require samples with thousands of individuals in order to produce meaningful results.
Until these large studies are available, it’s difficult for experts in mental health to use brain scan technology to personalize depression treatment or improve treatment outcomes.
In other words, research into brain scanning is still ongoing, and it might be some time before a quick scan of your brain is all it takes to identify the optimal medication, therapeutic approach or other form of treatment for your depression symptoms.
Although widespread brain scanning for depression is likely years or decades away, options are available if you’re feeling depressed and need help.
Most of the time, depression can be successfully treated using antidepressants, psychotherapy or a combination of different approaches.
If you think you might have depression, you can access expert help with our selection of online mental health services, including depression and anxiety medications and online therapy with a professional counselor.