Mood Disorders: Definition, Types, Symptoms, Causes, Treatments

Mood disorders are a category of mental health conditions that affect an individual’s emotional state and overall well-being. They are marked by extreme and persistent changes in mood, which significantly impact daily functioning.

The pooled rates for the 1-year prevalence of major depressive disorder (MDD) at 4.1%, dysthymic disorder at 2.0%, and bipolar I disorder at 0.72% according to Waraich P. et al 2004 study titled “Prevalence and Incidence Studies of Mood Disorders published in Canadian Journal of Psychiatry.

The types of mood disorders are classified into two main categories: depressive disorders and bipolar disorders. Depressive disorders include major depressive disorder, persistent depressive disorder, and disruptive mood dysregulation disorder. Bipolar disorders, on the other hand, are characterized by extreme shifts between highs (mania) and lows (depression).

The main symptoms of mood disorders vary depending on the specific condition. Still, they include feelings of sadness or emptiness, loss of interest in previously enjoyed activities, changes in appetite or sleep patterns, difficulty concentrating or making decisions, and thoughts of suicide or self-harm.

The main causes of mood disorders are complex and include biological, psychological, and environmental factors. Researchers believe that imbalances in certain brain chemicals, such as serotonin and dopamine, play a role in the development of mood disorders.

Genetics, trauma, chronic stress, and major life changes also contribute to their onset. Genetic factors explain about 35–45% of the variance in major depressive disorder and 65–70% in bipolar disorder, according to Bonacina et al.’s 2023 research titled “The Genetic Side of the Mood,” published in the Genes journal.

Treatment for mood disorders involves a combination of medication, therapy, and lifestyle changes. Antidepressants or mood stabilizers are prescribed to help manage symptoms, while therapy provides individuals with coping strategies and support.

What Is a Mood Disorder?

Mood disorders are a group of mental health conditions characterized by persistent and extreme changes in mood. These disorders significantly affect an individual’s emotional state, causing disruptions in daily functioning and overall well-being.

In 2019, about 970 million people worldwide lived with a mental disorder, with anxiety and depressive disorders being prominent, according to Charlson et al., in the article titled New WHO Prevalence Estimates of Mental Disorders in Conflict Settings published in the Lancet Journal.

How Common Are Mood Disorders?

Mood disorders are common in that 9.7% of U.S. adults experience any mood disorder in a given year, with females being more affected (11.6%) than males (7.7%), according to Kessler RC et al.’s 2009 study, “Design and Field Procedures in the US National Comorbidity Survey Replication Adolescent Supplement,” published in the International Journal of Methods Psychiatry Research. 

It is estimated that 20% of adults in Los Angeles County are living with a mental health disorder, according to the Office of the Surgeon General (US) 2001 report titled “Culture, Race, and Ethnicity” published in the National Institute of Mental Health (US).

This shows that mood disorders are relatively common in the United States, affecting a significant portion of the population. This is why it is important to increase awareness and understanding about these disorders, as well as provide access to proper treatment and support for those who are struggling.

What Are the Types of Mood Disorders?

The types of mood disorders are depressive disorders and bipolar disorders. Under depressive disorders, there are major depression, seasonal affective disorder, persistent depressive disorder, disruptive mood dysregulation disorder, premenstrual dysphoric disorder, depression related to a medical condition, and depression related to substance or medicine use. On the other hand, on bipolar disorders, we have bipolar I disorder, bipolar II disorder, cyclothymia, bipolar disorder related to a medical condition, and bipolar disorder associated with the use of certain substances.

The types of mood disorders are listed below:

Depressive Disorders

Depressive disorders are common mental health conditions that involve a persistent low mood, loss of interest, and an inability to experience pleasure. These disorders differ from typical mood fluctuations and feelings about everyday life events. Depression impacts all aspects of life, including relationships, school, and work. The major types of depressive disorders or depression include major depressive disorder, persistent depressive disorder (dysthymia), postpartum depression, and seasonal affective disorder.

Major Depression

Major Depressive Disorder (MDD), also known as clinical depression, is a mood disorder characterized by a persistent feeling of sadness and loss of interest or pleasure in normally enjoyable activities for at least two weeks. Major depression is a common condition, with an estimated 5% of adults globally affected, according to Bains N et al. ‘s 2023 study titled “Major Depressive Disorder,” published in the StatPearls Journal. MDD is triggered by a combination of genetic, environmental, and psychological factors, including family history, significant life changes, childhood trauma, chronic health problems, and substance use disorders.

Seasonal Affective Disorder

Seasonal affective disorder is characterized by recurring depressive symptoms that appear and disappear with the changing seasons. In the U.S., approximately 5% of adults experience SAD, with symptoms lasting around 40% of the year. SAD usually begins in the fall or winter and goes away in the spring or summer, according to Melrose, S et al. ‘s 2015 study, “Seasonal Affective Disorder,” published in the Journal of Depression Research and Treatment. The onset of seasonal affective disorder is triggered by decreased natural light during winter.

Persistent Depressive Disorder

Persistent depressive disorder is a chronic form of depression characterized by a persistently low or sad mood lasting for at least two years in adults or one year in children and adolescents. During this period, individuals experience a depressed mood for most of the day, more days than not, accompanied by at least two of the following symptoms: poor appetite or overeating.

Persistent depressive disorder affects approximately 1.5% to 2.5% of U.S. adults, according to Parker, G., & Malhi, G. S et al. 2018 study titled “Persistent Depression” was published in the Canadian Journal of Psychiatry. The onset of PDD is during adolescence, and it persists for many years or even decades.

Disruptive Mood Dysregulation Disorder

Disruptive Mood Dysregulation Disorder (DMDD) is a mental health condition in children and adolescents characterized by persistent irritability or anger and frequent temper outbursts that are disproportionate to the situation. Children with DMDD are at risk for developing anxiety and depressive disorders later in life. To qualify for a diagnosis of Disruptive Mood Dysregulation Disorder, a child must exhibit key. 

Premenstrual Dysphoric Disorder

Premenstrual Dysphoric Disorder (PMDD) is a severe mood disorder, recognized as a distinct condition in the DSM-5, and a disabling extension of premenstrual syndrome (PMS). Premenstrual Dysphoric Disorder is characterized by significant cognitive-affective and physical symptoms in a week or two before menses, with symptoms resolving a few days after the period starts. It affects up to 3-8% of menstruating women, according to Rapkin AJ et al. 2013 titled, “Treatment of Premenstrual Dysphoric Disorder” published in the Journal of Women’s Health.

Depression Related to a Medical Condition

Depressive Disorder Due to Another Medical Condition is a mood disorder characterized by a prominent and persistent period of depressed mood. The risk factors of this condition include stroke, multiple sclerosis, Huntington’s disease, Parkinson’s disease, hypothyroidism, Cushing’s disease, and traumatic brain injury. The common features of depressive disorders include sadness, emptiness, or irritable mood, accompanied by somatic and cognitive changes.

Meta-analyses and reviews indicate a high point prevalence of MDD in Parkinson’s disease (38%), epilepsy (22.9%), migraine (up to 47.9%), multiple sclerosis (30.5%), mild cognitive impairment (32%), and Alzheimer’s disease (41%), according to Berk, M., et al 2023 research titled, “Comorbidity Between Major Depressive Disorder and Physical Diseases” published in the Journal of World Psychiatry.

Depression Related to Substance or Medicine Use

Substance-induced depression is a mood disorder characterized by a prominent and persistent depressed mood that develops during or soon after substance intoxication or withdrawal or after exposure to a medication. A substance use disorder (SUD involves the uncontrolled use of a substance despite harmful consequences, leading to impaired daily functioning and changes in brain function. 

Depression affects how you feel, think, and act, with symptoms ranging from mild to severe, including persistent sadness, loss of interest, changes in appetite and sleep, fatigue, feelings of worthlessness, difficulty concentrating, and thoughts of death or suicide. 

About 5% of adults globally suffer from depression, according to Baig-Ward et al.’s 2023 study titled “The Individual and Societal Burden of Treatment,” published in The Psychiatric Clinics of North America Journal. Alcohol and drug use worsen the course of a depressive disorder by aggravating the symptoms of depression and increasing the likelihood of hospitalization.

Bipolar Disorders

Bipolar disorder, formerly known as manic depression, is a mental illness characterized by extreme shifts in mood, energy, thinking, and behavior, with the most common types being Bipolar I and Bipolar II. People with bipolar disorders experience periods of intense highs (mania or hypomania) and lows (depression), which can significantly affect their daily lives. During a manic episode, a person feels elevated or irritable mood, increased energy levels, racing thoughts, impulsive behavior, and decreased need for sleep.

Bipolar I Disorder

Bipolar I disorder is a mental health condition characterized by extreme shifts in mood and energy, from high (mania) to low (depression). To be diagnosed with Bipolar I, a person must experience at least one manic episode, which lasts a week or more, where they feel abnormally elevated or irritable with high energy and include abnormal behaviors. Bipolar I and II are the most commonly diagnosed subtypes of bipolar disorders, with bipolar I being more severe in terms of manic symptoms. 

Approximately 1% of the U.S. population has bipolar disorder. Still, many of those cases are undiagnosed or misdiagnosed, according to Singh, T. et al. ‘s 2006 study titled “Misdiagnosis of Bipolar Disorder” published in the Journal of Psychiatry.

 The disorder manifests in early adulthood after symptoms have persisted for several years. The main symptoms of Bipolar I include impulsivity decreased need for sleep, inflated self-esteem, and talkativeness during manic episodes.

Bipolar II Disorder

Bipolar II disorder is characterized by recurrent episodes of major depression and hypomania but without any history of full manic episodes. Hypomania involves an elevated or irritable mood, increased energy, and other symptoms like grandiosity, decreased need for sleep, rapid speech, racing thoughts, distractibility, and impulsive behavior. Bipolar II disorder is more common than Bipolar I disorder, with a lifetime community prevalence of around 5%, according to Benazzi F et al 2007 study titled, “Bipolar II Disorder” published in the CNS Drugs. The onset occurs in the teens or early 20s.

Cyclothymia

Cyclothymia, also known as cyclothymic disorder, is a milder form of bipolar disorder characterized by numerous periods of hypomanic and depressive symptoms that do not meet the criteria for full hypomanic or depressive episodes. To be diagnosed with cyclothymia, adults must experience these mood fluctuations for at least two years, while children and teenagers must experience them for at least one year. 

More than one-third (34.4%) of the total nonfatal burden in people with MDD was due to comorbid physical diseases, such as respiratory diseases, pain-related conditions, cardiovascular diseases, and gastrointestinal disorders, according to Berk, M., et al 2023 study titled, “Comorbidity Between Major Depressive Disorder and Physical Diseases” published in the Journal of World Psychiatry.

Bipolar Related to a Medical Condition

Bipolar disorder related to a medical condition is characterized by symptoms of mania, hypomania, or depression that are directly caused by a specific medical illness. The onset and triggering conditions are directly related to the underlying medical condition, such as Cushing’s disease, multiple sclerosis, stroke, or traumatic brain injury. The duration of the bipolar symptoms depends on the course and treatment of the underlying medical condition. 

In 2013, there were 48.8 million cases of bipolar disorder globally, a 49.1% increase from 32.7 million in 1990, due to population increase and aging, according to Ferrari AJ, et al 2013 study titled, “The Prevalence and Burden of Bipolar Disorder” published in the Journal of Bipolar Disord. 

Bipolar Related to the Use of Certain Substances

Bipolar disorder related to the use of certain substances is characterized by symptoms of mania, hypomania, or depression that are directly caused by the effects of drugs, alcohol, or medications. The symptoms include elevated mood, increased energy, racing thoughts, impulsivity, or irritability, as well as depressed mood, loss of interest, fatigue, and changes in sleep or appetite. 

The duration of the bipolar symptoms depends on the duration of substance use and the individual’s response to withdrawal or cessation of the substance. Between 40% and 70% of people with bipolar disorder have a history of substance use disorder, according to Ostacher MJ et al. ‘s 2006 study titled “Update on Bipolar Disorder and Substance Abuse” published in the Journal of Clinical Psychiatry.

What Are the Symptoms of Mood Disorders?

The main symptoms of mood disorders are categorized into two, that is under depressive disorder and bipolar disorder symptoms depressive disorder symptoms and bipolar disorder symptoms.

The symptoms of mood disorders are discussed below.

Depressive Disorder Symptoms 

The common symptoms of depressive disorder are given below:

• Sadness or emptiness
• Anxiety
• Hopelessness
• Helplessness
• Worthlessness
• Guilt
• Pessimism
• Irritability or frustration
• Negativity
• Anger

Bipolar Disorder Symptoms 

The common bipolar disorder symptoms are given below:

• Elation or joy
• Being on a natural high
• Higher levels of self-esteem than usual
• Invincibility
• Impulsivity
• Irritability
• Sadness
• Anxiety
• Excessive emotional sensitivity
• Hopelessness    

What Are the Causes of Mood Disorders?

The causes of mood disorders are biological factors, genetic factors, medical health conditions, environmental factors, and immune system issues. An imbalance of brain chemicals, coupled with genetic predispositions, stressful life events, and certain medical conditions, contributes to the development of these disorders.

Genes contribute 31-42% to major depressive disorder (MDD), according to Suktas, A. et al. ‘s 2024 study titled, “Genetic Polymorphism Involved in Major Depressive Disorder” in a Journal titled, “BMC Psychiatry.

The common causes of mood disorders are given below:

• Biological factors: Imbalances in brain chemicals, such as serotonin, norepinephrine, and dopamine, impact mood regulation.
• Genetic factors: A family history of mood disorders increases the risk of developing these conditions, suggesting a genetic component. A Swedish study found that the risk of bipolar disorder was 7.9, 3.3, and 1.6 times higher for first-, second-, and third-degree relatives, respectively, according to Coombes, B. J. et al.’s 2021 study titled “Genetic Contributions to Bipolar Disorder” published in the Journal of Psychological Medicine.
• Medical health conditions: Certain medical conditions, such as multiple sclerosis, dementia, and Parkinson’s disease, are associated with a higher likelihood of mood disorders. The lifetime prevalence estimates for mood measures are: major depressive episode (8.6%), major depressive episode with severity (7.7%), dysthymia (6.2%), major depressive episode with severity and dysthymia (3.4%), any bipolar disorder (1.6%), and any mood disorder (11.5%), according to Jonas BS et al 2003 study titled, “Prevalence of Mood Disorders in a National Sample of Young American Adults” published in the Social Psychiatry and Psychiatric Epidemiology.
• Environmental factors: Traumatic events, stressful life events, and childhood abuse increase the risk of developing mood disorders.
• Immune system issues: Immune system issues involve problems or dysregulation within the immune system.
• Sleep Deprivation: Lack of sleep has been linked to mood swings. A 2020 meta-analysis showed that sleep loss has a moderate effect on increasing negative mood states and a significant effect on decreasing positive mood, especially in younger people, according to Tomaso, C. Cet et al. ‘s (2020) study titled “The Effect of Sleep Deprivation and Restriction on Mood, Emotion, and Emotion Regulation” published in the Sleep Journal.

Who Is at Risk for Mood Disorders?

Anyone is at risk of experiencing mood disorders, regardless of age, with symptoms potentially emerging in the late teens to mid-20s. A study found that common risk factors for mood and anxiety disorders include being young, having a lower household income, being unmarried, experiencing more tremendous stress, and having poorer mental health, according to Meng X, et al 2012 research titled,  “Common and Unique Risk Factors and Comorbidity for 12-month Mood and Anxiety Disorders Among Canadians” published in the Canadian Journal of Psychiatry. 

Children with a family history of mood disorders, particularly depression or bipolar disorder, are at a higher risk, suggesting a genetic component. 

Environmental factors also play a significant role; stressful life events such as job loss, divorce, or the death of a loved one trigger or worsen mood disorders. Socioeconomic factors such as low household income and being unmarried increase the risk of mood and anxiety disorders.

How Are Mood Disorders Diagnosed?

Mood disorders are diagnosed by a psychiatrist or clinical psychologist who will complete a comprehensive health history and psychiatric evaluation. The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) is the standard used by clinicians and researchers to diagnose and classify mental disorders.

As part of the diagnostic process, a psychiatrist performs a physical exam to look for signs of illness and to rule out physiological causes for symptoms, such as thyroid disease or vitamin deficiency. They will review your symptoms, medical and family histories, and history of alcohol or drug use. 

Your psychiatrist will want to know about your past episodes of a mood disorder: How long were past episodes, how long did you go in between episodes, how intense were these episodes, and whether any of these episodes were affected by the use of street drugs or medicines? The psychiatrist will conduct an interview or survey, asking questions about your symptoms, sleeping and eating habits, and other behaviors.

What Are the Treatments for Mood Disorders?

The treatments for mood disorders are partial hospitalization program (PHP), Intensive outpatient program (IOP), and psychotherapy. These programs provide structured environments and therapeutic interventions tailored to individual needs, facilitating recovery and promoting stability.

The treatments for mood disorders are discussed below.

Partial Hospitalization Program (PHP)

A Partial Hospitalization Program (PHP) is a structured treatment approach designed for individuals requiring intensive care but not 24-hour hospitalization. It acts as a bridge between inpatient and outpatient care, providing a supportive environment for comprehensive treatment while allowing patients to maintain some independence. PHP is helpful for mood disorders because it offers a higher level of care than traditional outpatient therapy, helping individuals to stabilize their moods, manage their symptoms, and develop effective self-management strategies in a structured environment.

Intensive Outpatient Program (IOP)

An Intensive Outpatient Program (IOP) is a supportive transition between residential care and independent living. It provides a structured setting where individuals concentrate on recovery while continuing to manage their daily routines. IOP usually involves attending therapy sessions multiple days per week for a few hours each day, encompassing individual, group, and sometimes family therapy. IOP is particularly effective for individuals who do not require constant supervision but still need substantial support. It offers a balance of structure and flexibility that allows them to integrate treatment into their everyday lives.

Psychotherapy

Psychotherapy is a significant treatment option for mood disorders, with empirically supported treatments including cognitive behavioral therapy (CBT), interpersonal psychotherapy (IPT), and behavioral therapy. It involves various approaches, such as mental and behavioral therapies, interpersonal psychotherapy, and psychodynamic psychotherapy, tailored to address specific clinical issues. Psychotherapy is helpful for mood disorders because it allows individuals to work through their feelings and thoughts, manage their symptoms, and develop coping strategies.

What Medications Are Used to Treat Mood Disorders?

The medications used to treat mood disorders are antidepressants, mood stabilizers, and antipsychotics (neuroleptics). These medications work by correcting imbalances of chemicals in the brain to stabilize mood and prevent extreme mood swings.

Here’s how these medications help:

• Antidepressants: These medications increase serotonin levels in the brain to stabilize mood. They are mainly used to treat depression, which is the most common mood disorder. Examples include citalopram, fluoxetine, paroxetine, sertraline, and escitalopram.
• Mood stabilizers: These drugs treat and prevent highs (mania) and lows (depression). They reduce mood swings and prevent manic and depressive episodes. Examples include lithium, carbamazepine, lamotrigine, and valproic acid.
• Antipsychotics (neuroleptics): These medications treat mania or mixed episodes associated with bipolar disorder by targeting chemicals like dopamine and serotonin in the brain, preventing symptoms such as delusions and hallucinations.

What Are the Complications of Untreated Mood Disorders?

The complications of untreated mood disorders are difficulties in maintaining stable relationships, impulsivity and poor decision-making, and a person’s inability to hold down a job or complete educational goals, contributing to financial instability and decreased quality of life. 

The risk of self-harm or suicide attempts is also significantly higher in individuals with untreated mood disorders, with some studies showing a suicide rate 10 to 30 times higher than that of the general population, according to Dome, P. et al. ‘s 2019 study titled “Suicide Risk in Bipolar Disorder” published in the Journal of Medicine.

Substance abuse is another common complication, as individuals turn to drugs or alcohol to self-medicate and cope with their symptoms. Untreated mood disorders contribute to a decline in overall physical health due to increased stress, poor sleep patterns, inconsistent eating habits, and a higher risk of developing chronic health problems such as high blood pressure, heart disease, and diabetes. 

Over time, the longer a mood disorder goes untreated, the more severe the symptoms become, potentially leading to more frequent mood episodes and a higher rate of lifetime mood instability.

Are Women More Affected by Mood Disorders than Men?

Yes, women are more affected by mood disorders compared to men. Women are twice as likely to be diagnosed with major depressive disorder (MDD) compared to men and experience more symptoms and higher symptom severity. Women also report more subjective distress and are more likely to have comorbid anxiety disorders with MDD, while men are more likely to have comorbid substance abuse disorders. This sex difference in MDD incidence is consistent across cultures and community-based epidemiological studies. 

Mood disorders such as unipolar depression, generalized anxiety disorder, social anxiety disorders, and post-traumatic stress disorder (PTSD) are more commonly diagnosed in women than in men. Women are diagnosed with major depressive disorder (MDD) twice as often as men and typically experience more symptoms and greater severity of symptoms, according to Seney, M. L.et al. ‘s 2014 study titled “Sex Differences in Mood Disorders” published in the Journal of Biology of Sex Differences.

Is Mood Disorder Considered a Mental Health Condition?

Yes, mood disorders are considered mental health conditions. They are characterized by disturbances in mood, which impact an individual’s emotional state and ability to function normally. Mood disorders encompass a range of conditions, including depressive disorders such as major depressive disorder and dysthymia, as well as bipolar disorders like bipolar I and II and cyclothymic disorder. 

These conditions are recognized in the Diagnostic and Statistical Manual of Mental Disorders (DSM) and the International Classification of Diseases (ICD), authoritative sources for diagnosing mental health conditions. Major depressive episode (MDE) has a lifetime prevalence of 8.6%, while dysthymia is at 6.2%, according to Jonas B. Set et al. ‘s 2003 study, “Prevalence of Mood Disorders in a National Sample of Young American Adults,” published in the Social Psychiatry and Psychiatric Epidemiology Journal.  

Is Depression a Mood Disorder?

Yes, depression is classified as a mood disorder because it affects an individual’s emotional state. Depression is one of the most common types of mood disorders and is characterized by persistent feelings of sadness, loss of interest in activities, and changes in appetite, sleep, and energy levels. 

Depression is diagnosed based on the presence of specific symptoms for at least two weeks, impacting daily life and relationships. Approximately 280 million people worldwide experience depression, making it a common mental health condition, according to a study by Carreira-Míguez et al. 2022 study titled “Behavioral Patterns of Depression Patients and Control Population” published in the International Journal of Environmental Research and Public Health.

Is Anxiety a Mood Disorder?

No, anxiety is not classified as a mood disorder. Anxiety disorders are distinct from mood disorders, which include conditions like depression and bipolar disorder. Anxiety disorders are characterized by excessive fear and worry, leading to significant distress or impairment in functioning. 

While anxiety coexists with mood disorders, they are categorized separately. For instance, generalized anxiety disorder involves persistent worry, whereas mood disorders primarily affect mood, sleep, and energy levels. Anxiety precedes or coexists with mood disorders, but it is not classified under the same category. 
Anxiety disorders are the most common mental health disorders, affecting up to 33.7% of the population at some point in their lifetime. In the U.S., an estimated 19.1% of adults experience an anxiety disorder in a given year, according to H Penninx et al.’s 2021 study titled “Anxiety Disorders”, published in the Lancet Journal.