Major depressive disorder

• Overview:

  • Depression is a mood (affective) disorder characterised by persistent low mood, low energy and loss of interest/enjoyment in everyday activities (anhedonia)
  • Unipolar depression
  • Usually runs a relapsing and remitting course
  • Common - prevalence in UK around 4.5%
• Aetiology:

  • Is multifactorial with a combination of risk factors from biological, psychological and social categories
  • These factors can be predisposing, precipitating and perpetuating
  • Biological - family history, physical health problems and comorbid substance misuse
  • Psychological - personality traits, childhood trauma
  • Social - lack of social support, poor socioeconomic status, separated/divorced
• Protective factors:

  • Current employment
  • Good social support
  • Marital status - being married
• Biological risk factors:

  • Genetics - family history
  • Personality - dependent, anxious
  • Physical illness
  • Biochemical theories/monoamine deficiency - serotonin imbalance
  • Neuroendocrine - hypothalamic-pituitary-adrenal axis
  • Co-morbid substance misuse
  • Medications - beta-blockers and steroids
  • History of other mental illness
• Psychological risk factors:

  • Traumatic life events/childhood experiences
  • Environmental factors e.g. support
  • Low self esteem and negative automated thoughts e.g. helplessness, worthlessness
  • Lack of education
• NICE guidelines suggest using the DSM-V criteria to diagnose depressive disorders
• Diagnosis:

  • Presence of 5 of the following symptoms, for at least 2 weeks, one of which should be low mood or loss of interest/pleasure:
  • Low mood
  • Loss of interest or pleasure
  • Significant weight change
  • Insomnia or hypersomnia
  • Psychomotor agitation (restlessness) or retardation (slowed down actions)
  • Fatigue
  • Diminished concentration
  • Recurrent thoughts of death or suicide
• Psychotic symptoms:

  • If psychotic symptoms of depression are present, they are usually mood-congruent (match their thoughts and feelings)
  • Delusions - often revolving around guilt and personal inadequacy
  • Hallucinations - can be auditory, olfactory or visual
  • Mood-incongruent delusions or hallucinations that are non consistent with typical depressive themes are often associated with other psychiatric illness such as schizophrenia
• It is important to conduct a risk assessment, including: 

  • Risk to self: self-harm, suicide or neglect (commonest in depression)
  • Risk to others: when depression presents with psychotic features, such as command hallucinations, they may be at risk of harming others
  • Risk from others: patients with depressive symptoms may be more vulnerable to abuse, criminal acts or neglect
• Organic illness differentials:

  • Hypothyroidism
  • Cushing's disease or syndrome
  • Vitamin B12 deficiency
• Investigations:

  • Patient-health-questionnaire-9 (PHQ-9) for screening and severity of depression, or HADS
  • FBC - anaemia
  • TFTs
  • Vitamin B12 and folate
  • HbA1c
  • Serum cortisol
  • Imaging may be performed in patients with atypical features and signs indicative of an organic pathology e.g. sudden loss of memory and personality change
• Depression may then be classified in one of three categories of severity

  • Mild: few or no extra symptoms beyond the five to meet the diagnostic criteria
  • Moderate: symptoms and impairment between mild and severe
  • Severe: most or all the symptoms causing marked functional impairment with or without psychotic features
• Subthreshold depressive symptoms:

  • Subthreshold depressive symptoms: describes patients with a number of depressive symptoms (see above) not meeting the criteria described above.
  • Persistent subthreshold depressive symptoms: describes subthreshold depressive symptoms that persist for two years or more.
• Mild depression management:

  • Low-intensity psychological therapy and group CBT
  • Antidepressants should not be routinely offered unless there is a past history of moderate/severe depression, mild depression for 2 years or mild depression still present after other interventions
  • Sleep hygiene advice
  • Early follow up within 1-2 weeks
• Moderate-severe depression:

  • High-intensity psychological therapy
  • Antidepressant - first line SSRI
  • Severe depressive episode with psychotic symptoms - augmented with antipsychotic
  • ECT should be considered in severe cases where the patient has a strong preference, rapid treatment needed in cases of life-threatening depression, or multiple other treatments have failed
  • Sleep hygiene advice
  • Early follow up within 1-2 weeks
• Patients under 30 started on an SSRI or SNRI should be followed up within a week due to increased risk of suicide and self harm
• TCAs and venlafaxine should be avoided in patients with suicide risk or history of overdose due to risk of death from overdose
• Complications of depression:

  • Suicide - 4 times higher risk
  • Substance misuse
  • Persistent symptoms
  • Recurrence of depressive episodes
  • Antidepressant side effects - sexual dysfunction, risk of self harm, weight gain, hyponatraemia and agitation
• Recurrent depressive disorder is when the patient has had at least 2 depressive episodes
• PHQ-9:

  • 5-9 mild depression
  • 10-14 moderate depression
  • 15-19 moderately severe depression
  • 20-27 severe depression
• Hospital Anxiety and Depression Scale (HADS)

  • 8-10 mild depression
  • 11-14 moderate depression
  • 15-21 severe depression