Mood disorders, also known as affective disorders, are mental health conditions that are characterized by persistent feelings of sadness, irritability, or fluctuations in mood. Mood disorders can significantly impact a person’s thoughts, behaviors, activity levels, and overall quality of life. According to the National Institute of Mental Health, mood disorders are among the most common mental illnesses in the U.S., affecting around 10.4 million American adults each year.[1] The 5 most prevalent mood disorders are major depressive disorder, persistent depressive disorder, bipolar disorder, seasonal affective disorder, and premenstrual dysphoric disorder.
Major Depressive Disorder
Major depressive disorder (MDD), commonly known as clinical depression, is arguably the most widely diagnosed mood disorder. It is defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) as a condition characterized by one or more major depressive episodes lasting at least 2 weeks.[2] Symptoms include:
– Depressed mood for most of the day
– Markedly diminished interest or pleasure in activities
– Significant weight loss or gain
– Fatigue or loss of energy
– Feelings of worthlessness or excessive guilt
– Diminished ability to think or concentrate
– Recurrent thoughts of death or suicide
The exact causes of major depression are still being investigated, but research suggests that biological, psychological, and social factors can all contribute to its development. Genetics, changes in brain chemistry, childhood trauma, grief, social isolation, and substance abuse are just some of the potential risk factors.[3]
Major depressive disorder is very common, with around 7.6% of U.S. adults experiencing at least one major depressive episode in the past year. It affects women at nearly twice the rate of men.[1] Without treatment, episodes typically last 6 months or longer. MDD is highly treatable through medications like SSRIs, psychotherapy like cognitive behavioral therapy (CBT), or a combination approach.
Persistent Depressive Disorder
Previously known as dysthymia, persistent depressive disorder (PDD) is a chronic, low-grade form of depression. It involves having a depressed mood for most of the day, for more days than not, for at least 2 years (1 year for children).[2] Other symptoms are similar to major depression but tend to be less severe. People with PDD may experience:
– Poor appetite or overeating
– Low energy or fatigue
– Low self-esteem
– Poor concentration or difficulty making decisions
– Feelings of hopelessness
PDD often develops early in life and can persist for many years if left untreated. Up to 80% of people with PDD go on to experience episodes of major depression as well.[4] PDD affects around 1.5% of U.S. adults per year.[1] As with MDD, a combination of biological, psychological, and environmental factors likely contribute to PDD. Treatment usually involves antidepressant medication and psychotherapy.
Bipolar Disorder
Bipolar disorder is characterized by dramatic, alternating episodes of mania and depression. According to DSM-5 criteria, a manic episode involves an abnormally elevated, expansive mood lasting at least 1 week.[2] Symptoms of mania include:
– Inflated self-esteem or grandiosity
– Decreased need for sleep
– Extremely talkative and fast speech
– Racing thoughts or flight of ideas
– Increase in goal-directed activity
– Excessive involvement in risky behaviors
Manic episodes represent the “up” phase of bipolar disorder. They alternate with major depressive episodes, which represent the “down” phase. Bipolar disorder affects around 2.8% of U.S. adults per year.[1] Genetics and brain structure changes play key roles in its development. Treatment often involves mood stabilizing medications like lithium, anticonvulsants, antipsychotics, and/or psychotherapy.
Seasonal Affective Disorder
Seasonal affective disorder (SAD) is a type of depression that follows a seasonal pattern, typically occurring in fall and winter. SAD is associated with the reduced daylight hours of those seasons. Its key symptoms include:[5]
– Depressed mood
– Lethargy and fatigue
– Increased appetite and weight gain
– Cravings for carbohydrates
– Oversleeping
– Social withdrawal
Up to 10% of U.S. adults experience winter-pattern SAD, while a smaller percentage have summer-pattern SAD. Women are affected at higher rates than men. The exact causes are unknown but likely involve serotonin dysregulation and circadian rhythm disruptions due to less sun exposure. Light therapy, Vitamin D, antidepressants, and psychotherapy can help treat SAD.
Premenstrual Dysphoric Disorder
Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome (PMS) estimated to affect 2-5% of menstruating women.[6] PMDD involves severe mood and physical symptoms during the late luteal phase of the menstrual cycle, which improve after menstruation begins. Symptoms include:
– Marked mood swings
– Irritability or anger
– Depressed mood
– Anxiety
– Difficulty concentrating
– Fatigue
– Change in appetite
– Joint or muscle pain
– Breast tenderness
While the exact causes of PMDD are unclear, research suggests it may relate to sensitivity in some women to normal fluctuations in hormones like progesterone and estrogen levels throughout the menstrual cycle. Treatment may involve SSRIs, birth control pills, or other medications to stabilize hormones.
Conclusion
Major depressive disorder, persistent depressive disorder, bipolar disorder, seasonal affective disorder, and premenstrual dysphoric disorder are among the most prevalent mood disorders. While their symptoms and patterns vary, they share common features like persistent sadness, irritability, fatigue, changes in appetite, and other debilitating symptoms. Mood disorders often result from a complex interplay of biological, psychological, and environmental factors. Thankfully, through medications, psychotherapy, light therapy, and other treatments, most mood disorders can be effectively managed. Identifying mood disorders early and seeking professional treatment leads to the best outcomes.
References
[1] National Institute of Mental Health. (2022). Mental illness. https://www.nimh.nih.gov/health/statistics/mental-illness
[2] American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596
[3] Harvard Health Publishing. (2022). What causes depression? https://www.health.harvard.edu/mind-and-mood/what-causes-depression
[4] National Institute of Mental Health. (2022). Persistent depressive disorder. https://www.nimh.nih.gov/health/statistics/persistent-depressive-disorder
[5] Mayo Clinic. (2022). Seasonal affective disorder. https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/symptoms-causes/syc-20364651
[6] Penn Medicine. (2022). Premenstrual dysphoric disorder (PMDD). https://www.pennmedicine.org/updates/blogs/health-and-wellness/2017/march/premenstrual-dysphoric-disorder-pmdd