Depression

Overview

•Diagnosis requires ≥5 symptoms, present most of the day, nearly every day, for ≥2 weeks - at least one core symptom must be present

•Core symptoms (at least one required): low mood (often worse in morning); anhedonia

•Additional symptoms: fatigue, sleep disturbance (classically early morning waking), psychomotor change, appetite change, poor concentration/indecisiveness, feelings of worthlessness/guilt, recurrent thoughts of death/suicidal ideation

Investigations

•Exclude organic causes: TFTs (hypothyroidism), FBC (anaemia), U&E, glucose, B12/folate, LFTs

•Severity scoring: PHQ-9 (scored out of 27) - guides management pathway

•PHQ-9 ≤15 = 'less severe'; PHQ-9 >15 = 'more severe'

Management

Step 1 · Mild / subthreshold depression
1Active monitoring with follow-up normally within 2 weeks
2Consider guided self-help (IAPT referral)
3Avoid routine antidepressants (unless history of moderate/severe depression or symptoms >2 years)
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Step 2 · Mild-to-moderate depression (PHQ-9 ≤15)
1Psychological intervention (CBT via IAPT self-referral)
2Consider antidepressant if psychological therapy declined or ineffective, or chronic physical health problem complicates care
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Step 3 · Moderate-to-severe depression (PHQ-9 >15)
1Offer antidepressant + high-intensity psychological intervention (CBT) - most clinically and cost-effective combination
2First episode: prescribe generic SSRI - sertraline preferred first-line (lower drug interaction profile, including in chronic physical illness)
3Recurrent episode: prescribe antidepressant previously well tolerated/responded to
4Continue antidepressants for at least 6 months after remission; taper gradually to avoid discontinuation syndrome
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Children/young people (CAMHS-initiated)
Fluoxetine preferred in under-18s - initiated by CAMHS psychiatrist only
Age 18-25 starting antidepressants
Increased risk of impulsivity and suicidal ideation - arrange follow-up within 1 week of initiation (vs 2-4 weeks for >25). Warn patient and family explicitly.

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Sertraline is the preferred first-line SSRI - not venlafaxine (SNRI, more dangerous in overdose - reserve as alternative). Lithium and duloxetine are not first-line for a new diagnosis of depression.

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Refer to secondary care (psychiatry) if: high suicide risk, psychotic symptoms, suspected bipolar disorder, or severe depression unresponsive to treatment. Always ask about previous episodes of elevated mood before diagnosing unipolar depression - antidepressants alone can precipitate mania in bipolar disorder.

Depression vs pseudodementia in the elderly

Depression in older adults can closely mimic dementia ('pseudodementia') - distinguishing them is directly examinable.

Depression (pseudodementia) vs Alzheimer's disease
FeatureDepressionAlzheimer's disease
MMSE responses'I don't know' - lacks effortTries hard but answers incorrectly
Symptom durationWeeks to monthsGradual onset over years
Psychosocial triggerOften present (bereavement, retirement)Absent
Biological featuresPresent (early morning waking, appetite loss)Not prominent
MMSE scoreOften ≥23 (relatively preserved)Usually lower at diagnosis
Response to treatmentImproves with antidepressantsCognitive decline continues

Feature	Depression	Alzheimer's disease
MMSE responses	'I don't know' - lacks effort	Tries hard but answers incorrectly
Symptom duration	Weeks to months	Gradual onset over years
Psychosocial trigger	Often present (bereavement, retirement)	Absent
Biological features	Present (early morning waking, appetite loss)	Not prominent
MMSE score	Often ≥23 (relatively preserved)	Usually lower at diagnosis
Response to treatment	Improves with antidepressants	Cognitive decline continues

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MMSE scores: 24-30 = no cognitive impairment; 18-23 = mild cognitive impairment; 0-17 = severe cognitive impairment. A score ≥23-24 with 'I don't know' responses and clear psychosocial stressors strongly points to depression over dementia.