All of us feel moody sometimes due to failures in life. This is because life is not a bed of roses, and is perfectly normal, but is it depression? We often hear people say, “Oh I feel depressed” or “I am depressed” when actually, they are just feeling down (feeling sad).

What is the difference? What are some symptoms to look out for?

Depression vs low mood

Andrew Solomon said

The opposite of depression is not happiness, but vitality. And it was vitality that seemed to seep away from me in that moment. Everything there was to do seemed like too much work. (Solomon, 2013)

This talk was about how depression affected him and his life, so is a good introduction to the subject. For an “official” definition, NICE (The UKs National Institute for Health and Care Excellence) states in a 64 page document outlining recognition and management of depression:

If you are suffering with depression, you don’t have to suffer in silence. You are definitely not alone and there are many different forms of treatment for depression. You can talk to your doctor, who can refer you for counselling and other support as needed.

Depression is a broad and heterogeneous diagnosis. Central to it is depressed mood and/or loss of pleasure in most activities. Severity of the disorder is determined by both the number and severity of symptoms, as well as the degree of functional impairment. A formal diagnosis using the ICD-10 classification system requires at least four out of ten depressive symptoms, whereas the DSM-IV system requires at least five out of nine for a diagnosis of major depression (referred to in this guideline as ‘depression’). Symptoms should be present for at least 2 weeks and each symptom should be present at sufficient severity for most of every day. Both diagnostic systems require at least one (DSM-IV) or two (ICD‑10) key symptoms (low mood,^[1] loss of interest and pleasure^[1] or loss of energy^[2]) to be present.

Increasingly, it is recognised that depressive symptoms below the DSM‑IV and ICD‑10 threshold criteria can be distressing and disabling if persistent. Therefore this updated guideline covers ‘subthreshold depressive symptoms’, which fall below the criteria for major depression, and are defined as at least one key symptom of depression but with insufficient other symptoms and/or functional impairment to meet the criteria for full diagnosis. Symptoms are considered persistent if they continue despite active monitoring and/or low-intensity intervention, or have been present for a considerable time, typically several months. (For a diagnosis of dysthymia, symptoms should be present for at least 2 years^[3].)

It should be noted that classificatory systems are agreed conventions that seek to define different severities of depression in order to guide diagnosis and treatment, and their value is determined by how useful they are in practice. After careful review of the diagnostic criteria and the evidence, the Guideline Development Group decided to adopt DSM-IV criteria for this update rather than ICD-10, which was used in the previous guideline (NICE clinical guideline 23). This is because DSM-IV is used in nearly all the evidence reviewed and it provides definitions for atypical symptoms and seasonal depression. Its definition of severity also makes it less likely that a diagnosis of depression will be based solely on symptom counting.

In practical terms, clinicians are not expected to switch to DSM-IV but should be aware that the threshold for mild depression is higher than ICD-10 (five symptoms instead of four) and that degree of functional impairment should be routinely assessed before making a diagnosis. Using DSM-IV enables the guideline to target better the use of specific interventions, such as antidepressants, for more severe degrees of depression.

[1] In both ICD-10 and DSM-IV.

[2] In ICD-10 only.

[3] Both DSM-IV and ICD-10 have the category of dysthymia, which consists of depressive symptoms that are subthreshold for major depression but that persist (by definition for more than 2 years). There appears to be no empirical evidence that dysthymia is distinct from subthreshold depressive symptoms apart from duration of symptoms, and the term ‘persistent subthreshold depressive symptoms’ is preferred in this guideline.

(NICE, 2009)

The type of depression will depend on diagnostic criteria (see Different types of Depression below). But basically, depression is not just feeling sad. When you are depressed, it is difficult to carry on with day-to-day life effectively for varying reasons. This is over a period of days or more.

There are many grey areas in the assessment of depression, just like there are with some other mental health problems. The main traditional diagnostic systems used are currently the Diagnostic and Statistical Manual of Mental Disorders – DSM-5 (American Psychiatric Association, 2013) and the International Statistical Classification of Diseases and Related Health Problems – ICD-11 (WHO, 2018). A formal diagnosis using the ICD-11 classification system is as follows:

A [single] depressive episode is characterized by a period of almost daily depressed mood or diminished interest in activities lasting at least two weeks accompanied by other symptoms such as difficulty concentrating, feelings of worthlessness or excessive or inappropriate guilt, hopelessness, recurrent thoughts of death or suicide, changes in appetite or sleep, psychomotor agitation or retardation, and reduced energy or fatigue (ICD-11 6A70).
Recurrent depressive disorder is characterized by a history or at least two depressive episodes separated by at least several months without significant mood disturbance (ICD-11 6A71).

The DSM-5 system requires match in at least five out of nine criteria for a diagnosis of major depression, although there are moves to improve the diagnostic procedures for mental disorders through systems such as HiTOP (Stony Brook Medicine, 2017; Kotov, et al., 2017). However, one thing I think we can all agree on is that there are two different categories of depression.

• Endogenous
  Depression resulting from internal, possibly biological influences, as a result of possible genetic factors, or reactions to chemical/hormonal imbalances; and
• Exogenous
  Depression resulting from external influences in a person’s life, such as grief, loss or trauma.

Different types of depression

There are several types of depression.

• Unipolar Depression
  The sufferer feels melancholic with no experience of any highs. DSM-5 states that the criteria for diagnosis are the same as other forms of depression, however, the diagnosis is to be recorded with the specifier “with melancholic features” (p. 185).
• Bipolar Disorder (BPD)
  There are Bipolar I and Bipolar II disorders, both with severity levels of mild moderate and severe, and DSM-5 considers BPD to be a bridge between schizophrenia spectrum and other psychotic disorders in terms of symptoms, family history, and genetics; so, DSM-5 has a separated Bipolar Disorders from depressive disorders (p. 123).
  Suicide risk for Bipolar Disorders is 15 times greater than the general population, and may account for 25% of all completed suicides (p. 131), with a prevalence rate of 36.3% of attempts for Bipolar I and 32.4% for Bipolar II and in terms of genetics, the risk of suicide seems to be 6½ times higher among first-degree relatives (a person’s parent, sibling, or child) of those diagnosed with Bipolar II compared to Bipolar I (p. 138)
• Major Depression (Major Depressive Disorder in DSM-5 (p. 160))
  Looking at DSM-5, diagnosis requires five (or more) of the diagnostic criteria to be present most of the day, nearly every day, during the same 2-week period.
  Sufferers will feel down and uninterested in any activity external to them, and they are generally less motivated to deal with their basic needs. Suicidal behaviour has a possibility of existing at all times and most completed suicides are not preceded by unsuccessful attempts, with an increased risk of completion within men, and those who are single or living alone (p. 167).
• Mild Depression
  This sounds to be a separate disorder, with the sufferer still able to engage in life but finding their activities harder to do. However, looking at DSM-5, the criteria to look for are the same as Major Depressive Disorder, with few, if any, symptoms in excess of those required to make a diagnosis of Major Depressive Disorder (p. 162 & 188).
• Atypical Depression
  DSM-5 classifies this as the same as all other depressive disorders, but must have a specifier of “with atypical features”. DSM-5 goes on to say that Atypical Depression, compared to the past, does not connote an uncommon or unusual clinical problem as the term might imply. The levels of hypersomnia required are defined as at least 10 hours of sleep per day including daytime napping (or at least 2 hours more than when not depressed) (p. 186).
• Persistent Depressive Disorder (previously Dysthymia)
  Looking at DSM-5, this is a diagnosis which would be given when depression in any form is suffered for most of the day, for more days than not, over the last 2 years (p. 168). Sufferers may not be aware of the condition and just see it as part of life, whilst feeling unimportant, dissatisfied and scared.
• Psychotic Depression
  DSM-5 states that the criteria is the same as other forms of depression, however, the diagnosis is to be recorded with the specifier
  • “with psychotic features”
    (delusions and/hallucinations are present, of which some are mood-congruent, and some are mood-incongruent),
  • “with mood-congruent psychotic features”
    (the content of all delusions/hallucinations are consistent with the typical depressive themes of personal inadequacy, guilt, nihilism…) or
  • “with mood-incongruent psychotic features”
    (the content of all delusions/hallucinations are not consistent with the typical depressive themes of personal inadequacy, guilt, nihilism…) (p. 185).
• Seasonal Affective Disorder (SAD)
  This is depression which affects the sufferer during certain seasons. In most cases, SAD affects people during the autumn and winter months where daylight hours are less, but less commonly, there can be affects during the summer months due to heat and/or humidity or body image issues etc. (WebMD, 2017) DSM-5 requires this to be recorded the same as any other depression, but with the specifier “with seasonal pattern” (p. 187). This enables you to not diminish the severity of the depression since it is just seasonal.
• Postnatal Depression
  DSM-5 requires this to be recorded the same as any other depression, but with the specifier “with peripartum onset” (p. 186). This enables you to not diminish the severity of the depression since it is a result of giving birth to a child.
• Premenstrual Dysphoric Disorder
  There is a set of criteria laid out from page 171, with a requirement that the criteria must be met for most menstrual cycles that occurred in the preceding year and in most menstrual cycles, at least five symptoms must
  • be present in the final week before the onset of menses
  • start to improve within a few days after the onset of menses; and
  • become minimal or absent in the week post-menses

DSM-5 also talks about a depressive disorder which is specific to 7-18 year olds only, with onset before 10 years old, and that is Disruptive Mood Dysregulation Disorder (pp. 156-160).