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A chemical imbalance happens when there is too much or too little of any substance in the body that helps it function normally. While it can apply to an imbalance of any of these substances in any area of the body, the term is usually used to refer to imbalances in the brain.
This article discusses chemical imbalances in the brain, some of their symptoms, and what can cause them. It also explores the various treatments for chemical imbalances.
What Is a Chemical Imbalance?
A chemical imbalance occurs when the substances that help the body function the way it should become out of balance. Either too much or too little of these substances can cause a chemical imbalance that affects the body’s ability to function normally.
These chemical imbalances are often linked to health conditions. For example, a hormonal imbalance occurs with polycystic ovary syndrome (PCOS), which in turn puts a person at risk for other conditions such as type 2 diabetes and infertility.
Too much or too little of these substances anywhere in the body is considered a chemical imbalance. However, the term “chemical imbalance” is usually associated with chemical imbalances in the brain and their potential effect on mental health and related conditions.
Chemical Imbalances in the Brain
The chemicals in the brain that help facilitate communication between nerve cells are called neurotransmitters. Any disruption in the complicated process of nerve cell communication has the potential to affect the production and/or function of neurotransmitters and, by extension, a person’s mental health.
Some of the main neurotransmitters include:
- • Serotonin
- • Dopamine
- • Norepinephrine
- • Acetylcholine
- • GABA (gamma-aminobutyric acid)
- • Glutamate
These neurotransmitters help with many functions including:
- • Sleep
- • Appetite
- • Mood
- • Arousal
- • Behavior
- • Cognition
- • Pleasure
- • Early brain development
- • Memory
- • Learning
- • Stress response (“fight or flight”)
Dysfunction of these neurotransmitters has been linked to conditions such as:
- • Schizophrenia
- • Depression
- • Bipolar disorder
- • Parkinson’s disease
- • Anxiety disorders
Linked does not mean causative. It can reflect the effects of the underlying primary condition.
While it is common to hear that depression and some other mental health conditions such as anxiety disorders are caused by a chemical imbalance, most mental health experts believe the causes of mental health conditions are more complex than the term implies.3
The balance of chemicals in the brain is thought to be one influence on depression and anxiety disorders, along with a combination of factors such as:
- • Faulty mood regulation by the brain
- • Genetics
- • Environmental factors like stressful life events
- • Medications
- • Medical problems
Can Stress Cause a Chemical Imbalance?
In addition to affecting the balance of neurotransmitters, stress can affect chemical balances in multiple systems of the body including:
- • The nervous system
- • The digestive system
- • The endocrine (hormones) system
- • The cardiovascular system
- • The reproductive system
Mental Illness and Chemical Imbalances
Neurotransmitter levels that are too high or too low can contribute to various mental health conditions, but a "chemical imbalance" may be too simplistic as an explanation for these conditions.
Depression
The idea that depression is caused by a serotonin deficiency was popular in advertisements for antidepressant medications during the early 2000s, and many mental health professionals reiterated this explanation to their patients.
There was little evidence to make this definitive conclusion. Rather, while there is evidence that shows antidepressants like selective serotonin reuptake inhibitors (SSRIs) can be effective in the treatment of depression, the exact reason for how this improvement happens isn’t known.
“Chemical imbalance” and “serotonin deficiency” were used as a metaphor for the more complex workings of the brain and factors involved with depression. This erroneously led many people to believe that treating depression with antidepressants was like treating hypothyroidism with thyroid medications or type 1 diabetes with insulin—a simple matter of replenishing low serotonin.
More recent advertising highlights that the medication affects neurotransmitters instead of correcting an imbalance. This reflects the complexity and nuance involved in treating depression and how treatments for mental health conditions are not one-size-fits-all.
It’s suggested that there is no “optimal” amount of neurotransmitters, so it would be difficult to define an imbalance. In addition, medications that are not SSRIs have also been shown to alleviate depression symptoms. This implies that depression is more than a simple chemical imbalance.
While brain chemicals play a part in depression, things like nerve cell connections, nerve cell growth, and the functioning of nerve circuits also contribute to depression.
Addiction
Illicit drugs can cause changes in the reward processing center of the brain. They do so by interacting with naturally occurring chemicals such as dopamine, a neurotransmitter that is responsible for sending pleasure signals to the brain.
Drugs that create a sensation of euphoria cause a flood of dopamine, and over time, this causes the brain to become less efficient at producing, transmitting, and absorbing dopamine without the drug. When dopamine levels in the brain become abnormally low, the person using the drug becomes dependent on it.
Other Mental Health Issues
Other mental health issues are associated with neurotransmitters and other substances in the brain that are either too high or too low. Some of these include:
- Anxiety disorder: Anxiety disorder is thought to stem from an elevation or drop in certain neurotransmitters including dopamine, serotonin, norepinephrine, and gamma-aminobutyric acid (GABA).
- Schizophrenia: Chemicals implicated in schizophrenia include glutamate and dopamine. Some researchers also believe schizophrenia may be related to an imbalance of cytokines, proteins that are expressed in the brain and function as chemical messengers to help the body respond to infection.
- Bipolar disorder: Bipolar disorder has been associated with changes in the regulation of the neurotransmitters noradrenaline, serotonin, and dopamine.
- Mood swings: Mood swings can occur when serotonin levels in the brain change quickly. Because the hormones estrogen and progesterone help control serotonin production, many women will experience mood swings as their hormones fluctuate during the menstrual cycle or during menopause.
Chemical Imbalance in the Brain Symptoms
Symptoms of a chemical imbalance in the brain are associated with several psychiatric diagnoses.
Depression
There are several forms of depression, each with its own unique list of symptoms. Some of the most common types of depression include:
- Major depression. This type is a chronic state of depression that causes debilitating depression, loss of interest in activities, trouble sleeping, and feelings of worthlessness.
- Persistent depressive disorder. This type describes chronic low mood that persists over at least two years. It is less intense than major depression.
- Bipolar disorder. People with bipolar disorder experience episodes of depression and separate "manic" episodes of high energy.
- Seasonal affective disorder (SAD). People with this condition feel depressed in the fall and winter.
- Perinatal depression. This type occurs in females during pregnancy or in the first 12 months after giving birth.
- Premenstrual dysphoric disorder (PMDD). This type of depression affects only females and occurs between ovulation and menstruation.
Some of the more general symptoms of depression include:
- • Persistent sad, anxious, or “empty” mood
- • Feeling hopeless, negative, pessimistic
- • Irritability
- • Feelings of guilt, worthlessness, or helplessness
- • Loss of interest or pleasure in hobbies and activities (particularly ones you used to enjoy)
- • Decreased energy
- • Fatigue
- • Trouble concentrating, remembering, or making decisions
- • Sleep difficulties
- • Changes in weight or appetite
- • Thoughts of death or suicide, or suicide attempts
- • Unexplained physical symptoms, like aches, pains, headaches, and digestive problems
Anxiety Disorders
As with depression, there are several types of anxiety disorders that are best explored individually. Some of the major types include:
- Generalized anxiety disorder: Generalized anxiety disorder causes persistent feelings of anxiety that are strong enough to interfere with day-to-day activities and general well-being.
- Panic disorder: People with this type of anxiety disorder experience frequent panic attacks.
- Social anxiety disorder: Social anxiety disorder is associated with feelings of anxiety and intense fear of judgment during social interactions.
- Separation anxiety disorder: People with this condition experience fear when separated from family or close friends. This condition primarily affects children, but adults can experience it too.
- Phobia: People with phobias have an intense fear of certain things or situations that can be so strong that it interferes with daily life.
- Agoraphobia: Agoraphobia symptoms include intense fear and anxiety when venturing outside of the home. Crowds, public transportation, and open or enclosed places can trigger symptoms.
Some general symptoms of anxiety disorders include:
- • Feeling panic, fear, and uneasiness
- • Uncontrollable, obsessive thoughts
- • Repeated thoughts or flashbacks of traumatic experiences
- • Sleep difficulties
- • Difficulty sitting still
- • Nightmares
- • Unexplained physical symptoms such as cold or sweaty hands, dry mouth, muscle tension, or numbness/tingling in hands or feet
- • Heart palpitations
- • Nausea
- • Shortness of breath
Schizophrenia
Schizophrenia has been strongly linked to a chemical imbalance in the brain. Symptoms of schizophrenia include:
- • Delusions: False beliefs that are not based on reality
- • Hallucinations: Experiencing sensations, particularly seeing or hearing things, that are not real
- • Disorganized speech and behavior
- • Lack of emotion/flat affect: Emotions don’t show outwardly
- • Paranoia: Feeling like someone or something is out to get you
- • Withdrawal from others
Causes of Chemical Imbalances in the Brain
There are some things that may cause neurotransmitters to function improperly:
- • Receptors may be oversensitive or insensitive to a specific neurotransmitter, causing them to respond too much or too little to the release of the neurotransmitter.
- • If the originating cell pumps out too little of a neurotransmitter, the message may be weakened.
- • An overly efficient reuptake that reabsorbs too much before the molecules have the chance to bind to the receptors on other neurons can also weaken the message.
It is important to note that these factors apply to neurotransmitter disruption and do not necessarily cause a mental health condition in and of themselves.
It is also hypothesized that the mitochondria may play a part in the function of neurotransmitters and their role in depression.
Diagnosis
There is no reliable test for a chemical imbalance in the brain. Unlike some other chemicals in the body, neurotransmitters can’t be accurately measured.
Symptoms of mental health conditions such as anxiety or depression may indicate some problems with the way the brain—including the chemicals in the brain—is functioning.
The theory of chemical imbalance and its effect on mental health largely stems from the success in symptom reduction from medications when used to treat mental health conditions, but this link is far from clear-cut.
If conditions such as depression were conclusively caused by a chemical imbalance, antidepressants would work more quickly, as they impact levels of neurotransmitters relatively fast. However, they typically take several weeks to produce a noticeable effect.
Instead of making a diagnosis of a chemical imbalance in the brain, diagnoses of specific mental health conditions are made.
Treatments
Conditions that may be influenced by chemical imbalances in the brain might be treated with medications, psychotherapy, and lifestyle adjustments.
Medication
Antidepressants and other medications that affect brain chemistry are often prescribed to treat the conditions associated with a chemical imbalance. While these medications do help some people, they are not a cure-all.
Mental health disorders have multifaceted causes. While two people may share similar symptoms, they may have different pathologies and respond differently to treatment options.
Some medications prescribed to influence neurotransmitter function include:
Selective serotonin reuptake inhibitors (SSRIs)
SSRIs work by inhibiting the reuptake of serotonin. Examples include:
- • Celexa (citalopram)
- • Lexapro (escitalopram)
- • Luvox (fluvoxamine)
- • Paxil (paroxetine)
- • Prozac (fluoxetine)
- • Viibryd (vilazodone)
- • Zoloft (sertraline)
Serotonin and norepinephrine reuptake inhibitors (SNRIs)
SNRIs inhibit the reuptake of both norepinephrine and serotonin. Examples include:
- • Cymbalta (duloxetine)
- • Effexor (venlafaxine)
- • Fetzima (levomilnacipran)
- • Pristiq (desvenlafaxine)
- • Savella (milnacipran)
Tricyclic antidepressants (TCAs)
TCAs block the absorption of serotonin and norepinephrine and have several other impacts on neurotransmitters. Examples include:
- • Anafranil (clomipramine)
- • Asendin (amoxapine)
- • Elavil (amitriptyline)
- • Norpramin (desipramine)
- • Pamelor (nortriptyline)
- • Sinequan (doxepin)
- • Surmontil (trimipramine)
- • Tofranil (imipramine)
- • Vivactil (protriptyline)
Monoamine oxidase inhibitors (MAOIs)
MAOIs inhibit the action of an enzyme called monoamine oxidase, making more neurotransmitters available for use in mood regulation. Examples include:
- • Emsam (selegiline)
- • Marplan (isocarboxazid)
- • Nardil (phenelzine)
- • Parnate (tranylcypromine)
Atypical antidepressants
These are newer antidepressants that don’t fit into the above categories. Examples include:
- • Oleptro (trazodone) and Trintellix (vortioxetine): Serotonin antagonist and reuptake inhibitors (SARIs)
- • Remeron (mirtazapine): Impacts receptors of the stress hormone epinephrine (adrenaline) as well as impacting serotonin in the brain
- • Wellbutrin (bupropion): Dopamine and norepinephrine reuptake inhibitor
Antipsychotics
Antipsychotics are used to manage psychosis (a loss of contact with reality). Examples of first-generation (“typical”) antipsychotic medications include:
- • Chlorpromazine
- • Haloperidol
- • Perphenazine
- • Fluphenazine
Examples of second-generation (“atypical”) antipsychotic medications include:
- • Risperidone
- • Olanzapine
- • Quetiapine
- • Ziprasidone
- • Aripiprazole
- • Paliperidone
- • Lurasidone
Non-Pharmaceutical Treatment
Psychotherapy treatments such as cognitive behavioral therapy (CBT) can be effective for many mental health conditions. These therapies may affect the function of neurotransmitters by changing neural pathways and associations.
For some people, exercise is helpful in symptom relief for depression and anxiety, in part by stimulating chemicals in the brain that make your body (and, in turn, your mind) feel better.
Non-pharmaceutical treatments may be enough on their own to help some people with depression or anxiety but are often used in combination with medication.
