Any given year, approximately 18.5% of adults in the United States, or 43.8 million people, will experience mental illness. This includes nearly 16 million adults in the United States who have suffered at least one episode of major depression in the past year. The World Health Organization estimates that worldwide, more than 300 million people suffer from some form of depression, making it the leading cause of disability in the world. Defined by the National Institute of Mental Health as a common but serious mood disorder, major depressive disorder (MDD) causes severe symptoms known to affect how a person thinks, feels, behaves, and functions in daily life. Several possible causes include genetic, biological, environmental, and psychological factors. Depression can be very difficult to diagnose and subtype due to its fluid nature and overlapping symptoms, as is the case with many mental illnesses. Nonetheless, mental health professionals have long tried to better define and understand depression’s subtypes in the hope that it would aid treatment efforts. Although it can be difficult to separate these different subtypes, clusters of symptoms have enabled the recognition of eight variations of major depressive disorder: postpartum, seasonal, catatonic, psychotic, anxious, mixed, melancholic, and atypical.
One of the most common subtypes of MDD, postpartum depression occurs in women after they give birth, and is believed to occur in approximately 15% of births (NIMH.gov). According to the DSM-V, the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders published by the American Psychiatric Association, symptoms must start within four weeks of giving birth in order for a major depressive episode to be considered postpartum depression. In the event symptoms begin during pregnancy, which is the case for roughly 50% of patients, the disorder is then referred to as “peripartum” depression (DSM-V). Significantly more severe than the usual “baby blues” that accompanies childbirth, postpartum depression poses serious challenges for new mothers, hampering their ability to care for themselves and their newborn. Commonly causing fatigue, insomnia, social withdrawal, and an irritable mood (all symptoms that most new mothers have mild forms of), patients may also fear that they are not good mothers and have difficulty bonding with their newborns. In severe cases, mothers may have thoughts of hurting themselves or their babies (mayoclinic.org). While there is no known specific cause for depression, the various subtypes are believed to have different causes. In the case of postpartum depression, while there is no single cause, it is very likely that the emotional and physical stress a pregnant woman experiences plays a role (mayoclinic.org).
Another widespread, relatively mild form of MDD is seasonal affective disorder, or SAD, a recurring mood disorder related to the changes in seasons. Characterized by episodes of depression that recur annually at around the same time of year, SAD affects more than 3 million people in the United States per year (mayoclinic.org). While SAD is traditionally related to the fall and winter months, the Mayo Clinic notes that although less common, SAD can cause depression in the spring and early summer. Interestingly, while both fall-onset and spring-onset SAD may cause symptoms typical of major depression, they also each present their own unique symptoms. In the case of fall and winter depression, symptoms may resemble the traits of a hibernating animal, such as social withdrawal, weight gain, increased sleep, low energy, and irritability. This starkly contrasts with the symptoms specific to spring and summer depression, which include insomnia, weight loss, anxiety, and a poor appetite. As for potential causes, lower levels of natural sunlight in the fall and winter may disrupt the body’s circadian rhythm as well as decrease serotonin and melatonin levels, potentially triggering depression. For these reasons phototherapy, or light therapy, may be an effective treatment for fall-onset SAD (mayoclinic.org). However, patients can take solace in the fact that seasonal affective disorder is just that: seasonal. Although it returns annually, it does not last continuously, unlike the next form of depression.
Rather than a subtype of MDD, the most chronic form of depression is actually a mild mood disorder known as persistent depressive disorder, or dysthymia. When compared to the subtypes of MDD, the biggest distinctions between these two disorders are the duration and relative severity of their symptoms. While the symptoms of MDD occur in major depressive episodes that on average last six months, dysthymia is a chronic depression whose symptoms continuously last at least two years, with some cases lasting a lifetime (Lavid, DSM-V). At the same time, dysthymia’s symptoms are typically not as severe as those of MDD. Patients with dysthymia may exhibit more moderate forms of common MDD symptoms, such as a loss of interest in previously enjoyed activities and feelings of hopelessness, sadness, guilt, and personal inadequacy (mayoclinic.org). It is also worth noting that contrary to popular belief, depression (including both MDD and dysthymia) does not necessarily always cause sadness, but may instead cause extreme apathy or emptiness. However, depression is directly associated with sadness for a reason, and there are two forms in particular that while less prevalent, both have the potential to cause extremely severe symptoms.
Not limited to causing mental symptoms, major depressive disorder can also cause severe physical symptoms, as shown by the rare subtype known as catatonic depression. Characterized by causing disturbances in motor behavior, catatonia may also cause a marked decrease in reactivity to the environment, decreased engagement and reactivity, or excessive and peculiar physical activity. In addition, patients may maintain rigid or bizarre postures, and repeat stereotyped movements like staring and grimacing. Like in all disorders, symptoms range from severe to mild, with stupor and mutism, which cause a complete lack of physical and verbal responses to external stimuli, respectively, representing the severe end of the spectrum (mayoclinic.org, DSM-V).
Although slightly more common than catatonic depression, psychotic depression is by no means any less complex or severe. Having two distinct forms, mood-congruent and mood-incongruent, psychotic depression is characterized by the patient suffering delusions and hallucinations (DSM-V). Whether or not the themes of these delusions and hallucinations match their depressed mood are what define each subtype. The content of the hallucinations of patients with mood-congruent psychotic depression is always based on depressed themes, such as personal inadequacy, guilt, disease, death, and deserved punishment. On the other hand, the delusions of patients with mood-incongruent psychotic depression do not involve those typical depressed themes, although they may suffer from a mix of themes (DSM-V). Currently, the best treatment for psychotic depression may very well be electroconvulsive therapy (ECT), or electroshock therapy (Marano).
Depression with anxious distress is the most common subtype of MDD, with estimates that it makes up about 40% of all cases (Marano). Known for it’s difficulty to treat, patients are less likely to respond to treatment, resulting in a longer average recovery time. Combine this with a younger average age (20.6 years vs 28.4 for all patients), and it is easy to see why anxious depression can cause major problems in patients’ social, work, or school lives. It is also worth noting that about 40% of patients experienced symptoms of anxiety before they experienced depression (Marano). The symptoms of depression with anxious distress include the “presence of at least two of the following symptoms on the majority of days during an episode”: feeling keyed up or tense, feeling unusually restless, difficulty concentrating because of worry, a fear that something awful may happen, and a feeling and/or fear that the individual might lose control of themselves (DSM-V, mayoclinic.org). Although some of these symptoms may not seem to “fit” the typical idea of depression, this is not the only subtype to have such symptoms.
One of the more difficult subtypes to properly diagnose is mixed depression, or a mixed affective state, a form of depression that also presents symptoms of mania. Along with typical symptoms of MDD, the DSM-V states that at least three of the following symptoms are present nearly every day and during the majority of days of an episode: an elevated or expansive mood, an inflated self-esteem, being more talkative than usual or feeling a pressure to keep talking, a flight of ideas or the subjective experience that one’s thoughts are racing, an increase in energy or goal-directed activity (either socially, at work or school, or sexually), an increased or excessive involvement in activities that have a high potential for painful consequence, and a decreased need for sleep (feeling rested despite sleeping less than usual). The difficulty to properly diagnose mixed depression stems from the fact that symptoms may closely resemble bipolar disorder. In fact, if all symptoms of mania are met, that is most likely what the disorder is. Now down to the final two subtypes, these stand on their own in terms of their symptoms and natures.
Arguably the most severe subtype of depression is melancholic depression, believed to have a completely biological cause and the subtype of MDD most often resulting in patients being hospitalized (Kennard, Marano). Before going further, it is important to remember the difficulty faced in judging the severity of depression, especially when relying on a patients experiences. Although few mean to, most patients with depression believe they are doing worse than they actually are, at least relatively, because they don’t have a scale to base their judgement off of besides themselves.
Characterized by a near-complete absence of the ability to feel pleasure, the symptoms of melancholic depression are undoubtedly severe. While patients may be able to experience about 20% – 40% of happiness for short periods at a time, they almost always have extreme anhedonia (DSM-V, Black Dog Institute). In addition, the DSM-V states that patients have “three (or more) of the following” symptoms: a distinct quality of depressed mood characterized by profound despair or apathy, depression that is regularly worse in the morning, early-morning awakening (at least 2 hours before usual) or insomnia, marked psychomotor agitation or retardation, significant anorexia, weight loss, or lack of appetite, and excessive or inappropriate guilt, potentially caused by replaying the same thought or experience repeatedly.
Finally, there is atypical depression, an extremely common subtype and one whose nature defies most ideas of classical depression. Making up an estimated 23% to 36% of all cases of major depressive disorder, atypical depression is believed to affect 10 million people in the United States alone (Marano). Significantly more common in women than men, atypical depression also tends to have an earlier age of onset and be more chronic than the average case of depression (DSM-V).
Atypical depression, true to its name, has symptoms that do not match the conventional, classical view of depression that other subtypes, notably melancholic depression, fit so well. Rather, the defining feature of atypical depression is mood reactivity, or the capacity for a patient to be cheered up when presented with positive events. This means that a patient with atypical depression can actually feel better, if only for a short time. Compare this to melancholic depression, where a patient cannot feel sustained happiness (if they are even able to feel happiness at all), and the unique nature of atypical depression is revealed. In addition to the aforementioned mood reactivity, the DSM-V states that patients must have two (or more) of the following symptoms present during the majority of days of their MDD episode: significant weight gain or increase in appetite, hypersomnia (sleeping at least 10 hours a day), leaden paralysis (heavy, leaden feeling in arms or legs), and a long-standing pattern of interpersonal rejection sensitivity that results in significant social or occupational impairment.
Although the boundaries between subtypes can often be fuzzy and overlap, psychologists aim to define them in the goal of better treatment. However difficult it may be, and whether or not there is any practical benefit to it yet, by analyzing symptoms and treatment reactions, eight variations of major depressive disorder have been recognized. From the recurring seasonal affective disorder to the highs and lows of mixed depression, and from the depths of melancholic depression to the reactive nature of atypical depression, these variations help doctors better understand depression, and that will always help patients.