Dopamine's Role in Mental Illness

What Is Dopamine?

Dopamine is a neurotransmitter (a chemical released by nerve cells) that plays an important and diverse role in how your brain functions. Often called "the feel-good hormone," dopamine is involved in reward, motivation, and addiction. This chemical messenger is also involved in the coordination of body movements.

The Role of Dopamine

Dopamine transmits chemical messages between neurons (brain and nerve cells) by binding to dopamine receptors. The action is similar to a key slipping into a lock.

Dopamine has a variety of functions and impacts multiple areas of the brain, including:

• Amygdala, which plays an important role in processing.
• Hippocampus, which is important for memory.
• Insular cortex (also called the insula), which is important for homeostasis, or how your body maintains a proper temperature, signals that you’re hungry, regulates heartbeat and breathing, and generally keeps things running properly.
• Motor cortex, which deals with movement.
• Prefrontal cortex, which is important for problem-solving, complex thinking, memory, intelligence, and language.

Bodily Functions

Dopamine plays a role in many important physical functions in your body, including:

• Blood vessel function
• Cognitive functions involving attention, learning, and working (short-term) memory
• Control of nausea and vomiting
• Heart rate
• Kidney function
• Lactation
• Pain processing
• Sleep and dreaming
• Voluntary movement

Mental Health

Dopamine has an important role in mental function and emotional response, including impulse control and mood regulation. There are a number of dopamine-related mental health conditions, including:

• Addiction
• Attention-deficit hyperactivity disorder
• Binge-eating disorder
• Bipolar disorder
• Depression
• Obsessive-compulsive disorder
• Schizophrenia

Motivation and Reward

In addition to movement, emotion, memory, and thinking, dopamine neurons are involved in motivation and reward. This is why certain substances of abuse, especially cocaine and nicotine, are addictive. These substances stimulate the dopamine-mediated reward system in the brain. 

Dopamine rewards you whenever you engage in a beneficial behavior and motivates you to repeat the behavior. However, engaging in vices like alcohol or recreational drugs also causes dopamine to be released into the brain. This is why the chemical messenger has been closely linked to addiction.

High vs. Low Dopamine

Having high or low dopamine activity can impact your health in a variety of ways, depending on the region of the brain where dopamine activity is excessive or inadequate.

Symptoms of high dopamine activity include:

• Aggression
• Anxiety
• Excess energy or mania
• Hallucinations
• High sex drive
• Increased feelings of stress
• Insomnia
• Improved focus and learning ability

Symptoms of low dopamine activity include:

• Chronic back pain
• Persistent constipation
• Weight fluctuations
• Dysphagia or difficulty swallowing
• Sleep disorders
• Fatigue
• Attention difficulties
• Reduced sex drive
• Hallucinations and delusions
• Aspiration pneumonia
• Low moods

There are a variety of factors that can cause fluctuations in dopamine levels, including:

• Drug misuse
• Obesity
• Saturated fat
• Sleep deprivation
• Stress

Mental Illness

Besides Parkinson's disease, a number of psychiatric illnesses have been linked to dopamine dysregulation like schizophrenia, attention-deficit hyperactivity disorder, bipolar disorder, and depression. The manner in which dopamine has affected these psychiatric illnesses is unique.

Depression

Low levels of dopamine have been found to form the basis of the symptoms associated with major depressive disorders, including lack of interest and motivation.

Attention-Deficit Hyperactivity Disorder

In attention-deficit hyperactivity disorder (ADHD), impairment in the dopamine system causes poor attention. This is why stimulants, like Ritalin (methylphenidate) or Adderall (amphetamine), which increase dopamine levels in the brain, help improve attention and alertness.

Borderline Personality Disorder

Some researchers believe that dopamine dysfunction may be involved in the development of borderline personality disorder (BPD). This mainly stems from studies that support dopamine's role in thinking, regulating emotions, and impulse control, all of which are impaired in people with BPD. Also, antipsychotic medications seem to reduce some BPD symptoms, especially those of anger and cognitive problems (like paranoid thinking).

That being said, other experts argue that the manner in which antipsychotics benefit patients with BPD is through non-dopamine pathways. Overall, it's hard to say at this time how critical dopamine is in the development or course of BPD. More research will be helpful in elucidating this connection. 

Schizophrenia

In schizophrenia, the dopamine system is overactive. This is why medications that block dopamine receptors in the brain (called antipsychotics) are used in its treatment. 

Other neurotransmitters, including GABA and glutamate, have been found to be important in the psychiatric disorder as well.

Binge-Eating Disorder

One study suggested that a heightened sensitivity to reward, which could manifest as a strong dopamine signal in the brain, could be a contributing factor to BED.

Certain medications that impact dopamine function are sometimes used to treat BED.

A Word From Verywell

Only a medical professional can diagnose a dopamine-related disorder, so if you think that you or someone you love is experiencing low or high levels of dopamine, it's important to schedule a visit with a qualified health care provider.

The dopamine system is an intricate, fascinating system that participates in a number of different neurological and mental functions. By further examining dopamine's role in the brain, scientists will hopefully gain the information they need to develop more targeted dopamine medications—so people with dopamine-mediated illnesses, like schizophrenia, can get well and avoid undesirable side effects.