Depression And Neurotransmitters: The Connection

Medically reviewed by Nikki Ciletti, M.Ed, LPC

Updated October 9, 2024by BetterHelp Editorial Team

Depression, or major depressive disorder (MDD), is a common mental illness that’s estimated to affect around 5% of adults worldwide. Researchers haven’t isolated a single cause of depression that’s applicable in every case. Instead, it’s thought to be caused by any of various combinations of factors such as environment, stressful experiences, genetics, and balances of certain brain chemicals. To find out how brain chemicals in particular may lead to a person developing major depression, see below for recent research and information on the topic.

Facing mental health challenges?

Get support from a compassionate therapist

Depression, defined

Depression is a type of mood disorder that can affect virtually anyone of any age, gender, race, or background. Signs of this mental illness can appear after a person has gone through a difficult life experience, such as a divorce or the loss of a loved one, or seemingly without a clear external cause. Symptoms of major depressive disorder usually include:

A loss of interest in activities once enjoyed
Persistent feelings of sadness
Feelings of hopelessness and/or worthlessness
Significant changes in appetite
Significant changes in sleep patterns
Irritability
Social isolation
Fatigue
Excessive crying
Thoughts of self-harm and/or suicide

If you or someone you know is experiencing suicidal thoughts or behaviors, seek help immediately. The National Suicide Prevention Lifeline can be reached 24/7 by dialing 988.

Note that signs of depression in children and teens may differ somewhat from those seen in adults. If you or your child are experiencing symptoms of a mental illness like major depressive disorder, it’s generally recommended that you seek the support of a qualified healthcare professional.

The potential link between neurotransmitters and depression

Our emotions are the result of biological reactions to external stimuli. Our bodies react to things that happen on a chemical level, and those reactions can affect our emotions. Key components of this process are chemicals called neurotransmitters. Responsible for conveying signals between nerve cells, neurotransmitters influence many processes, such as the development of our emotions. That’s why emotions often come with recognizable, physical symptoms, like an increased heart rate when we’re scared or an increased body temperature when we’re angry.

Serotonin seems to be an important neurotransmitter when it comes to the biology of depression. It appears to impact mood and to control a number of physical functions, including sleep patterns and digestion. A key theory on the cause of depression states that this may be why depression—which some theorize is caused by an issue with serotonin levels—can leave a person with persistent feelings of sadness and hopelessness in addition to physical symptoms like significant changes in appetite and/or sleeping patterns.

The theory that a serotonin imbalance can cause depression is still accepted by many. However, it is important to note that there’s been increased debate on this theory more recently as new research emerges.

Some studies have failed to find a link between serotonin and incidences of depression. Research on other potential causes is ongoing.

What causes low serotonin levels?

Researchers are still aiming to understand exactly what might cause low levels of serotonin, but various theories have gained significant support. One is that not getting enough sunshine could result in lower levels of these neurotransmitters. Another is that exercise can trigger the release of certain brain chemicals, including serotonin, so those that live sedentary lifestyles may be at risk of low levels of this neurotransmitter and therefore of depression. Research findings that suggest that frequent exercise can be an effective treatment for the condition in some cases would seem to support this theory.

Lifestyle factors may not be the only ones that could cause lower levels of serotonin than may be healthy. Some people may have genetic abnormalities or health conditions that could cause issues with the release and reception of this chemical. For example, some individuals seem to simply not produce enough serotonin, while others might lack adequate receptors to receive the molecules and put them to use. Still others may use serotonin too slowly, meaning that the rest gets absorbed through other channels before it can be used to positively affect mood.

Getty/Vadym Pastukh

Medication for serotonin levels

The theory that depression may be caused by issues with serotonin levels has led to the now relatively common prescription of selective serotonin reuptake inhibitors (SSRIs) for those with this mental illness. These medications aren’t designed to simply increase serotonin levels in the body, since serotonin receptors can gradually become immune to the molecule if bombarded by it. Instead, they’re meant to help make the most of the serotonin that is available already by preventing the body from absorbing the chemical before the brain has a chance to use it.

Note that SSRIs are typically not recommended as a standalone treatment for depression. Instead, they’re often intended to help a person manage their symptoms enough to be receptive to other types of treatment, such as talk therapy—which is the first-line treatment for depression in most cases. Keep in mind as well that while SSRIs can be very helpful for some people, they’re not necessarily right for everyone in every situation. Some individuals may not be able to take them due to interactions with other medications, while others may experience undesirable side effects from them. Still others may prefer to explore non-pharmacological treatment options first before turning to a treatment like SSRIs. If you’re curious about starting, stopping, or changing medication for depression, it’s always recommended that you talk to your doctor first to avoid potentially dangerous effects.

Facing mental health challenges?

Get support from a compassionate therapist

Other treatments for depression

As mentioned, talk therapy is usually the first suggested treatment for depression. Cognitive behavioral therapy (CBT) is one of the most common modalities, because it aims to help clients learn how to recognize and then shift distorted thought patterns that may be causing distress. Your doctor, psychiatrist, or therapist may also recommend certain lifestyle changes that could help you manage your symptoms. Exercise, as mentioned above, seems to be effective in decreasing symptoms of depression for many. Eating nutritious foods may help too, as may getting enough sleep and cultivating strong social connections.

Therapy for depression

If you’re interested in speaking to a therapist about your depression symptoms or engaging in talk therapy, you can typically choose between online and in-person care. For those who have a busy schedule or simply prefer attending sessions from the comfort of home, online therapy can be a more convenient way to receive this type of treatment. With a platform like BetterHelp, you can get matched with a licensed therapist who you can meet with via phone, video call, and/or in-app messaging to address the challenges you may be facing. Research suggests that online therapy can help reduce depression symptoms in many cases, so it may be worth considering if this format is more comfortable for you.

Takeaway

Research about what exactly causes depression is ongoing. Most experts have come to believe that it’s typically some combination of genetics, environment, experiences, and/or brain chemistry. The theory about brain chemistry has to do with serotonin levels, which is why SSRIs are sometimes prescribed for those experiencing this mental illness. If you’re living with symptoms of depression, it’s typically recommended that you meet with your doctor or therapist for evaluation and treatment advice.

Frequently asked questions

Read more below for answers to questions commonly asked about this topic.

How do neurotransmitters contribute to depression?

While a variety of psychological, environmental, and biological factors can contribute to depression, certain neurotransmitters may be associated with the disorder. Three neurotransmitters that have the potential to contribute to depression are norepinephrine, dopamine, and serotonin.

Norepinephrine: Norepinephrine is connected to various functions like energy levels, emotional control, memory, and attention. Low levels of this neurotransmitter may contribute to the frequency or severity of depressive symptoms.
Dopamine: Processes like concentration and motivation are connected to dopamine. Without an appropriate level of specific brain chemicals like dopamine, these functions may be disrupted, which can exacerbate depression.
Serotonin: Serotonin is responsible for a variety of roles within the body, such as mood modulation, digestion, and healthy sleep. The disruption of these processes can worsen depressive symptoms.

What 3 neurotransmitters are linked to depression?

Research suggests that the three neurotransmitters most closely linked with depression are dopamine, serotonin, and norepinephrine. Of these three neurotransmitters, one of the most studied in relation to depression is serotonin. Reduced levels of tryptophan, which is instrumental in the synthesis of serotonin, may lead to a higher risk of developing generalized depression. Dopamine, on the other hand, may relate more closely to specific symptoms like anhedonia, or the inability to feel pleasure, while norepinephrine may be related to difficulties with memory or energy.

What neurotransmitter is released during depression?

Some research theories suggest that a depletion of neurotransmitters like norepinephrine, dopamine, and serotonin may be related to depression. Other neurotransmitters may also play a role in depression, such as gamma-aminobutyric acid (GABA) and acetylcholine. While often discussed in relation to anxiety, the GABA neurotransmitter is known for its ability to calm the mind and body. Like other vital neurotransmitters, people experiencing depression may have lower GABA levels than is necessary to maintain certain bodily functions. Acetylcholine, on the other hand, is associated with memory and learning functions. Because these are often impacted by depression, researchers believe that those experiencing depression may also have lower acetylcholine levels.

What neurotransmitters are involved in anxiety and depression?

A variety of neurotransmitters may be involved in anxiety and depression, including serotonin, dopamine, glutamate, norepinephrine, and acetylcholine. In addition, low levels of neurotransmitters like gamma-aminobutyric acid (GABA) can also contribute to the development of anxiety and depression, as well as the exacerbation of existing symptoms. GABA works with other neurotransmitters like glutamate (which has a variety of roles, including modulating cerebral blood flow) and serotonin to transmit messages between nerve cells in order to control certain bodily functions. These chemical messengers play a key role in relieving feelings of anxiety, ensuring healthy sleep, and reducing chronic stress levels.

What neurotransmitters cause stress?

The category of neurotransmitters most closely related to physical and psychological stress are known as catecholamines, which include epinephrine (also known as adrenaline), norepinephrine (noradrenaline), and dopamine. Other chemicals like the stress hormone cortisol also play a significant role in the body’s stress response. Sometimes referred to as “fight-or-flight”, this response is traditionally used as a way for your body to react in life-or-death situations. However, the body may activate this response as a reaction to non-threatening stressful life events as well, which can be harmful to your health.

How does dopamine affect depression?

Dopamine may affect depression and other mood disorders due to its association with mood management. Low levels of dopamine may cause or worsen specific depressive symptoms, including:

Chronic fatigue
Low levels of motivation
A lack of interest in previously enjoyable activities
Feelings of guilt or shame

Sleep disturbances
Unhealthy coping mechanisms like substance misuse
Difficulty concentrating
Impulsive behavior

It’s important to note that there may not be a way to reliably measure the levels of dopamine in an individual’s brain. However, clinical psychiatry may have methods to address the ways that low dopamine and depression affect a person’s mind, while a medical doctor may be able to help treat their physical symptoms.

What neurotransmitters cause mental disorders?

While specific neurotransmitters may not directly cause depression, they may affect certain brain regions or cause a change in symptom severity. Several neurotransmitter categories may be linked to depression, including:

Monoamines like norepinephrine, serotonin, and dopamine
Amino acids like phenylalanine, tryptophan, tyrosine, and kynurenine
Acetylcholine, including both receptor types: nicotinic and muscarinic
Purines like adenine and guanine
Exosomes
Neuropeptides
Steroids

However, further research may need to be conducted to conclusively determine the precise association these neurotransmitters have with depression. It's also important to note that there may not be ways for doctors to test for levels of these neurotransmitters, which may make it more difficult to determine what connection they have to the development of depression.

Which neurotransmitter is responsible for happiness and anxiety?

While a number of factors can affect whether someone experiences happiness or anxiety, two key neurotransmitters (serotonin and dopamine) may be closely linked to these processes. Serotonin and dopamine play vital roles in managing mood, with high levels of dopamine being associated with positive mood and high levels of serotonin being linked to more feelings of happiness, optimism, and satisfaction. However, some individuals (like those with depression) may not be able to produce healthy levels of these neurotransmitters. This may be helped by certain treatments like selective serotonin reuptake inhibitors, which are commonly used to treat depression. However, these medications may not be appropriate for some forms of depression, such as psychotic depression and atypical depression.

How do neurotransmitters affect emotions?

The category of neurotransmitters that may affect emotions most significantly are monoamines, including norepinephrine, dopamine, and serotonin. These neurotransmitters are involved in a number of processes, including the reward system, emotions like fear, and the body’s stress response. While high levels of these chemicals may result in positive feelings, an optimistic outlook, consistent happiness, and a more satisfied mindset, low levels can have a variety of negative effects. These effects may include difficulty sleeping (including both falling asleep and staying asleep), a lack of interest or pleasure in previously enjoyable activities, mood swings, and poor impulse control.

Which hormone is responsible for depression?

While hormones may not be directly responsible for clinical depression, a decrease in certain hormones could result in a depressive episode. Two hormones that fall under this category are estrogen and testosterone, which both can impact the frequency and severity of depressive symptoms. Low levels of testosterone can not only lead to depressive episodes, but may also increase feelings of anxiety, lower sex drive, and lead to chronic fatigue. Low levels of estrogen can have similar effects, in addition to symptoms like hot flashes, erratic periods, and tender breasts.

Depression is treatable, and you're not alone

Talk to a compassionate counselor

The information on this page is not intended to be a substitution for diagnosis, treatment, or informed professional advice. You should not take any action or avoid taking any action without consulting with a qualified mental health professional. For more information, please read our terms of use.

You don't have to face depression aloneGet started

Top Categories

See all categories