Every once in a while I’m overcome with the motivation to do some public education — ultimately, I do want that to be a large part of my career, but for now by blog will have to do. This week, I thought I’d mimic a bit of the curriculum from one of my current classes and have a quick chat about the different diagnoses that you might come across — specifically in the depression category.

I’m a big fan of research. When I’ve been diagnosed over the years, I’ve done a lot of research into what each diagnosis means and how it might affect me. I’m hoping that this post might be a resource for someone in a similar position.

Please note that this information is based on the current and previous Diagnostic and Statistical Manual for Mental Disorders (DSM-5 & DSM-4) and is not exhaustive, containing only the most common diagnoses.

(And here’s a bit of a table of contents if you’re inclined.)

• Major Depressive Disorder (MDD)
  • Seasonal Affective Disorder (SAD)
  • Peripartum (Postpartum) Depression
• Persistent Depressive Disorder (PDD)

Major Depressive Disorder (MDD)

This is largely the disorder that is referred to when we talk about depression or ‘clinical depression.’ MDD is a disorder where major depressive episodes are recurrent or last for more than two weeks.

Let’s go through the DSM-5’s diagnostic criteria. The first major criteria evaluates what we consider to be the ‘main symptoms’ of depression:

1. Five (or more) of the following symptoms have been present during the same 2-week period and represent a change from previous functioning; at least one of the symptoms is either (1) depressed mood or (2) loss of interest or pleasure.

   Note: Do not include symptoms that are clearly attributable to another medical condition.

   1. Depressed mood most of the day, nearly every day, as indicated by either subjective report (e.g., feels sad, empty, hopeless) or observation made by others (e.g., appears tearful). (Note: In children and adolescents, can be irritable mood.)
   2. Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day (as indicated by either subjective account or observation.)
   3. Significant weight loss when not dieting or weight gain (e.g., a change of more than 5% of body weight in a month), or decrease or increase in appetite nearly every day. (Note: In children, consider failure to make expected weight gain.)
   4. Insomnia or hypersomnia nearly every day.
   5. Psychomotor agitation or retardation nearly every day (observable by others, not merely subjective feelings of restlessness or being slowed down).
   6. Fatigue or loss of energy nearly every day.
   7. Feelings of worthlessness or excessive or inappropriate guilt (which may be delusional) nearly every day (not merely self-reproach or guilt about being sick).
   8. Diminished ability to think or concentrate, or indecisiveness, nearly every day (either by subjective account or as observed by others).
   9. Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide.
2. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
3. The episode is not attributable to the physiological effects of a substance or to another medical condition.

An important part of the discussion around MDD includes defining a major depressive episode. A major depressive episode is defined as fulfilling the criteria A through C of MDD (the information quoted above); major depressive episodes can be present in a variety of disorders or present without the presence of a disorder.

An important part of the diagnosis of MDD in the DSM-5 is ruling out the possibility of other intermediating factors causing a depressive episode. This is outlined in a note in the criteria:

Responses to a significant loss (e.g., bereavement, financial ruin, losses from a natural disaster, a serious medical illness or disability) may include the feelings of intense sadness, rumination about the loss, insomnia, poor appetite, and weight loss noted in Criterion A, which may resemble a depressive episode. Although such symptoms may be understandable or considered appropriate to the loss, the presence of a major depressive episode in addition to the normal response to a significant loss should also be carefully considered. This decision inevitably requires the exercise of clinical judgment based on the individual’s history and the cultural norms for the expression of distress in the contest of loss.

Finally, the diagnostic criteria seeks to distinguish MDD from other potential disorders where a major depressive episode may be present:

4. The occurrence of the major depressive episode is not better explained by schizoaffective disorder, schizophrenia, schizophreniform disorder, delusional disorder, or other specified and unspecified schizophrenia spectrum and other psychotic disorders.
5. There has never been a manic episode or a hypomanic episode.

   Note: This exclusion does not apply if all of the manic-like or hypomanic-like episodes are substance-induced or are attributable to the physiological effects of another medical condition.

Seasonal Affective Disorder (SAD)

In the DSM-5, SAD is actually labeled as ‘major depressive disorder with seasonal pattern,’ though it is more commonly known as seasonal affective disorder. As a subset of MDD, the diagnostic criteria for SAD are identical but with episodes recurring during the winter months when there is less sunshine. Learn more about SAD from the American Psychiatric Association, who create the DSM.

Peripartum (Postpartum) Depression

Another subset of MDD is peripartum depression, commonly known as postpartum depression — it is classified in the DSM-5 as major depressive disorder with peripartum onset. The peripartum qualifier is used when the onset of MDD or of an episode is during pregnancy or within four weeks of giving birth. The American Psychiatric Association has a page with more information on postpartum depression.

Persistent Depressive Disorder (PDD)

Previously called ‘dysthymic disorder’ or ‘chronic major depressive disorder,’ PDD is a constant state of low mood which does not go away for at least two years. The DSM-5 criteria follow:

1. Depressed mood for most of the day, for more days than not, as indicated by either subjective account or observation by others, for at least 2 years.

   Note: In children and adolescents, mood can be irritable and duration must be at least 1 year.

2. Presence, while depressed, of two (or more) of the following:
   1. Poor appetite or overeating.
   2. Insomnia or hypersomnia.
   3. Low energy or fatigue.
   4. Low self-esteem.
   5. Poor concentration or difficulty making decisions.
   6. Feelings of hopelessness.
3. During the 2-year period (1 year for children or adolescents) of the disturbance, the individual has never been without the symptoms in Criteria A and B for more than 2 months at a time.
4. Criteria for a major depressive disorder may be continuously present for 2 years.
5. There has never been a manic episode or a hypomanic episode, and criteria have never been met for cyclothymic disorder.
6. The disturbance is not better explained by a persistent schizoaffective disorder, schizophrenia, delusional disorder, or other specified or unspecified schizophrenia spectrum and other psychotic disorder.
7. The symptoms are not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication) or another medical condition (e.g., hypothyroidism).
8. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.

A note about the possible comorbidity of MDD is included in the criteria as well:

Because the criteria for a major depressive episode include four symptoms that are absent from the symptom list for persistent depressive disorder (dysthymia), a very limited number of individuals will have depressive symptoms that have persisted longer than 2 years but will not meet criteria for persistent depressive disorder. If full criteria for a major depressive episode have been met at some point during the current episode of illness, they should be given a diagnosis of major depressive disorder. Otherwise, a diagnosis of other specified depressive disorder or unspecified depressive disorder is warranted.

Though PDD is occasionally thought of as a ‘less severe’ form of depression than MDD, both are incredibly distressing and can be very disruptive.

I’m thinking that I might continue on doing posts like these every once in a while, working through different categories of mental illness; anxiety disorders, personality disorders, psychotic disorders, and bipolar disorders come to mind. If there’s anything else that you want to see, leave a comment and let me know!

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