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What is the most common mood disorder in the US?

Mood disorders are a category of mental health conditions that affect how a person regulates their emotions. Mood disorders involve persistent feelings of sadness or periods of extremely elevated mood that impair functioning. The most common mood disorders in the United States are major depressive disorder and bipolar disorder.

Major depressive disorder, also known as clinical depression, is characterized by persistent feelings of sadness, emptiness, hopelessness, and loss of interest in previously enjoyable activities. It affects different aspects of a person’s life including their mood, thoughts, behavior, physical health, and ability to function in daily activities.

Bipolar disorder, formerly known as manic depression, causes dramatic shifts in mood, energy, activity levels, concentration, and the ability to think clearly. People with bipolar disorder alternate between depressive episodes and manic or hypomanic episodes.

Prevalence of Mood Disorders

Mood disorders are among the most common mental illnesses in the United States. According to the National Institute of Mental Health (NIMH), in 2019 there were an estimated 21.0 million adults aged 18 or older in the United States with at least one major depressive episode in the past year. This represented 8.4% of all U.S. adults.

The NIMH reports that 7.8% of U.S. adults had at least one major depressive episode with severe impairment in 2019. Severe impairment is when symptoms interfere with a person’s ability to manage daily life activities such as working, studying, eating, and maintaining relationships.

Bipolar disorder affects approximately 4.4% of U.S. adults per year based on diagnostic criteria from the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5). An estimated 2.8% of U.S. adults have bipolar I disorder and 1.5% have bipolar II disorder in a given year.

Here is a summary of the prevalence of mood disorders among U.S. adults annually:

Mood Disorder Prevalence
Major depressive disorder 21.0 million (8.4%)
Severe major depressive disorder 7.8%
Bipolar I disorder 2.8%
Bipolar II disorder 1.5%

Based on these statistics, major depressive disorder is clearly the most prevalent mood disorder experienced by adults in the United States annually. About 1 in 12 Americans suffer from clinical depression each year.

Gender Differences

Research shows that mood disorders affect certain groups at higher rates. Specifically, studies find significant gender differences in the prevalence of depressive and bipolar disorders.

Women have much higher rates of major depressive disorder compared to men. According to 2019 NIMH data, 10.5% of adult females had at least one major depressive episode in the past year compared to only 6.1% of males.

The prevalence of severe, impairing depression is also greater in women. In 2019, 8.7% of women 18 and older had major depression with severe impairment versus 6.8% of men.

Studies indicate that females are about twice as likely as males to develop depressive disorders. Possible reasons for the higher rate in women include hormonal fluctuations related to menstruation, pregnancy, miscarriage, postpartum periods, and menopause. Women may also be more impacted by stressful life events, trauma, disappointing life experiences, poor body image, and low self-esteem.

In contrast, bipolar disorder affects men and women at similar rates overall based on population data. However, there are differences in the type of bipolar disorder experienced. Bipolar I disorder, which involves full manic episodes, is slightly more common in males. Bipolar II disorder, characterized by hypomania instead of full mania, is more prevalent among women.

Here is a summary of gender differences in mood disorder prevalence:

Mood Disorder Females Males
Major depressive disorder 10.5% 6.1%
Severe major depressive disorder 8.7% 6.8%
Bipolar I disorder Equal rates Slightly higher
Bipolar II disorder Slightly higher Equal rates

Age of Onset

Mood disorders frequently develop during adolescence and young adulthood. The median age of onset is 32 years old for major depressive disorder and 25 years old for bipolar disorders. However, mood disorders can begin at any age.

Studies indicate that 50% of all lifetime cases of mental illness begin by age 14 and 75% begin by age 24. Early diagnosis and treatment is important since adolescent mood disorders increase the risk of problems like substance abuse and suicide during the teen years.

The typical age of onset for major depression ranges from the 20s to 30s, although it impacts all age groups. Bipolar disorder onset also peaks between ages 15 and 24. However, there is often a substantial delay between symptom onset and diagnosis of bipolar disorder due to factors like incorrect diagnoses and reluctance to seek treatment early. The average gap between onset of bipolar symptoms and diagnosis is 5 to 10 years.

Late onset mood disorders that develop after age 50 may have different characteristics and risk factors like cognitive deficits and neurological conditions. However, most older adults with mood disorders experienced recurrent episodes earlier in life.

Here is an overview of the typical age of onset for mood disorders:

Mood Disorder Median Age of Onset
Major depressive disorder 32 years old
Bipolar disorder 25 years old

In summary, although mood disorders can begin at any age, the peak years of onset are during adolescence and young adulthood. This makes early intervention and treatment extremely important.

Comorbidity with Other Disorders

It is common for mood disorders to occur alongside other mental and physical health conditions. This comorbidity can make mood disorders more difficult to diagnose and treat.

Anxiety disorders frequently co-occur with both depression and bipolar disorder. Up to 60% of people with bipolar disorder also have an anxiety disorder like generalized anxiety disorder, panic disorder, or a phobia. Around 50% of individuals with major depression also have an anxiety disorder.

Substance use disorders are another common co-occurring illness. About 20% to 50% of individuals with bipolar disorder also have a substance use disorder. And approximately 20% of people with major depression have alcohol dependence or abuse. Self-medication with drugs or alcohol can exacerbate mood disorder symptoms.

Attention-deficit/hyperactivity disorder (ADHD) often coexists with both depressive and bipolar disorders as well. Around 9.5% of youth with depression also have ADHD. Up to 20% of adults with bipolar disorder have co-occurring ADHD. Difficulty concentrating is a shared symptom which can complicate diagnosis.

Other mental health conditions associated with mood disorders include eating disorders like bulimia nervosa and borderline personality disorder marked by instability in emotions, behavior, self-image, and relationships.

Here is an overview of some of the most common conditions that co-occur with mood disorders:

Co-occurring Condition Major Depression Bipolar Disorder
Anxiety disorders 50% Up to 60%
Substance use disorders 20% 20-50%
ADHD 9.5% in youth Up to 20% in adults

In terms of physical health conditions, mood disorders have been linked with increased risk for conditions like heart disease, stroke, diabetes, obesity, and headaches. Sleep disorders are also more common among people with clinical depression and bipolar disorder.

Overall, co-occurring mental and physical disorders are the rule rather than the exception with mood disorders. Screening for other conditions is an important part of accurate diagnosis and effective treatment.

Causes and Risk Factors

Mood disorders do not have a single cause but instead result from a complex interaction of biological, psychological, and social-environmental factors.

Biologically, mood disorders have been linked to changes in brain chemistry and structure. Neurotransmitter imbalances in the regulation of serotonin, dopamine and norepinephrine play a key role. Hormonal influences from the stress response system are also involved. Genetics contribute as mood disorders run in families.

Psychological trauma and stress, especially early in life, can increase vulnerability. Adverse childhood experiences like abuse, neglect, family conflict, and exposure to violence are associated with dramatically elevated risks for depressive and bipolar disorders later in life. Ongoing stressful life events can trigger episodes in adulthood as well.

Cognitive and personality style impacts risk too. Negative thought patterns, poor coping abilities, and low self-esteem are linked to both major depression and bipolar disorder. But an overly optimistic outlook may also contribute to bipolar disorder.

Social and environmental factors like childhood poverty, discrimination, social isolation, and lack of support networks have been tied to greater risk for mood disorders. Cultural influences that stigmatize mental illness and certain lifestyles may prevent people from accessing treatment.

Here are some of the main risk factors that can influence a person’s likelihood of developing a mood disorder:

Type of Risk Factor Examples
Biological Family history, genetics, brain chemistry imbalances, hormonal changes
Psychological Trauma, high stress, negative thought patterns, low self-esteem
Social/Environmental Adverse childhood experiences, poverty, discrimination, social isolation

Identifying individual risk factors can help providers screen for and diagnose mood disorders early. A holistic treatment approach considers biological, psychological, and social components.


Mental health professionals use the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) to diagnose mood disorders based on symptoms, duration, and level of impairment.

For major depressive disorder, at least five of the following symptoms must be present most of the day, nearly every day for a minimum of two weeks:

– Depressed mood
– Markedly diminished interest or pleasure in activities
– Significant weight loss or gain
– Sleep disturbances
– Fatigue or loss of energy
– Feelings of worthlessness or guilt
– Diminished ability to think or concentrate
– Recurrent thoughts of death or suicide

The symptoms must cause significant distress or impairment in daily functioning without being attributable to another condition. There are specifiers for factors like severity and psychotic features like hallucinations or delusions.

To diagnose bipolar I disorder, patients must meet the criteria for a manic episode defined by three or more of these symptoms for one week or longer:

– Inflated self-esteem or grandiosity
– Decreased need for sleep
– Increased talkativeness
– Racing thoughts
– Distractibility
– Increased activity driven by high energy
– High risk behavior such as overspending and sexual promiscuity

The mood disturbance must be severe enough to cause social and occupational impairment. A major depressive episode is usually present as well.

Bipolar II disorder involves meeting major depression criteria along with at least one hypomanic episode lasting four days or longer. Hypomania symptoms are similar to mania but less extreme. Bipolar disorders can also be categorized as cyclothymic, rapid cycling, or mixed state.

Proper diagnosis guides treatment decisions and helps avoid misdiagnosis of normal mood variations as bipolar disorder or dismissing major depression as regular sadness. Ongoing tracking of symptoms is important due to shifting symptom patterns over time.


Treatment for mood disorders aims to reduce symptoms, restore functioning, and prevent relapse. A combination of medications, psychotherapy, and lifestyle changes is often most effective.

For major depression, first-line medications usually include selective serotonin reuptake inhibitors (SSRIs) like fluoxetine, sertraline, citalopram, and paroxetine. Other options include serotonin-norepinephrine reuptake inhibitors (SNRIs), atypical antidepressants, tricyclic antidepressants, and monoamine oxidase inhibitors (MAOIs).

Medications commonly prescribed for bipolar disorder include lithium, anticonvulsants, atypical antipsychotics, and antidepressants combined with a mood stabilizer. Treatment is lifelong as this disorder is chronic, often requiring complex medication regimens to manage different phase symptoms.

Cognitive behavioral therapy (CBT) helps patients identify distorted thinking patterns and make behavioral changes. Interpersonal therapy focuses on improving communication and relationships. Other therapeutic approaches include dialectical behavior therapy and family psychoeducation.

Establishing regular sleep, exercise, nutrition, and social interaction routines helps maintain mood stability. Joining a support group provides community with others facing similar challenges. Reducing substance use and developing crisis management plans are also important.

Without treatment, both major depression and bipolar disorder tend to recur frequently and intensify over time with a high risk of self-harm behaviors. Ongoing treatment adherence and lifestyle balance helps manage symptoms long-term.

Prognosis and Outcomes

With appropriate treatment, many people with mood disorders can manage their symptoms and regain a good quality of life. However, mood disorders are frequently chronic conditions with periodic relapses.

For major depressive disorder, each episode carries about a 50% to 60% risk of recurrence over time. After two or three episodes, the risk may exceed 80%. Some experience chronic, unremitting depression.

Among people with bipolar disorder, 60% to 70% have another manic or major depressive episode within five years. The cycles may accelerate over time with progressive treatment resistance and cognitive decline. About 15% to 20% have chronic symptoms without optimal symptom control despite treatment.

Functional outcomes vary widely depending on symptom severity, treatment access, social supports, and comorbidities. Severe cases of mood disorders with suicidal thoughts, psychosis, or inability to care for oneself require intensive treatment, monitoring, and supports.

Mood disorders also increase mortality risk from suicide as well as indirect impacts like poor health habits and medication side effects. However, early recognition, evidenced-based care, therapeutic relationships, and self-management support can greatly improve long-term prognosis.


In summary, major depressive disorder is by far the most prevalent mood disorder experienced by American adults annually at a rate of about 8.4%. Women have significantly higher rates of depression compared to men.

Bipolar disorders affect approximately 4.4% of the U.S. population each year. Onset for both major depression and bipolar disorder peaks in adolescence and young adulthood. Co-occurring mental and physical health conditions are common.

Complex interactions between biological, psychological, and social factors contribute to mood disorder development. A combination of medication, psychotherapy, and healthy lifestyle changes is the most effective treatment approach.

While mood disorders are frequently chronic, active management of symptoms can help patients achieve functional recovery and improved quality of life. Ongoing treatment adherence, social support, and coping skills development are key for better long-term outcomes. Increased awareness, early intervention, evidence-based care, and reduced stigma can help people thrive while managing these challenging conditions.