7.5.7 Mood disorders in older people

Depression in later life

Epidemiology

Depression is not a normal part of ageing, and the diagnostic criteria are the same as in younger adults.

• About 10 to 15% of people aged 65 and over in the community have clinically significant depression, most of it below the threshold for major depressive disorder.

Clinical picture

• Risk factors include previous depression, bereavement, loneliness, pain, disability, financial strain and medicines such as corticosteroids and opioids.

• Older people may report anxiety, sleep disturbance, pain or fatigue more readily than sadness, so ask about anhedonia, hopelessness and function.

• Depression that begins in later life shows more prominent psychomotor change, either slowing or agitation, than depression that began earlier.

• Depressive pseudodementia is a historical term for depression dominated by poor concentration and memory; it neither proves reversibility nor excludes neurodegeneration.

Cognition and imaging

• Current depressive severity predicts cognitive performance in major depressive disorder better than age at onset or past severity.

• Structural imaging in late-onset depression shows tissue loss and small vessel damage, with ventricular enlargement rather than shrinkage.

Vascular depression

• Vascular depression (Alexopoulos) is depression of first onset after 65 in someone with vascular risk factors.

• Apathy and slowing outweigh sadness, guilt is slight, and executive dysfunction is present.

• MRI shows periventricular and deep white matter hyperintensities.

• The Alexopoulos hypothesis holds that subcortical ischaemic damage to frontal-subcortical circuits causes it.

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Psychotic depression

• Psychotic depression in later life brings mood-congruent delusions of poverty or guilt: a fixed belief of being ruined and deserving punishment.

• Cotard's syndrome is the nihilistic belief that the person or their organs no longer exist.

• Treat with an antipsychotic alongside the antidepressant, or with ECT.

Differential diagnosis

• In bereavement, briefly hearing the dead partner's voice is common and not psychotic, and a wish to join the partner differs from suicidal intent.

• Delirium is told apart by acute change and altered attention and arousal.

• Apathy reduces motivation and emotional engagement, sometimes without sadness.

• Physical causes include thyroid disease, hypercalcaemia, anaemia, Parkinson's disease, stroke, subdural haematoma and malignancy.

• New depressive symptoms in established dementia call for a search for a physical cause, with bloods and urinalysis, before any antidepressant or therapy.

• Ask about previous mania or hypomania before prescribing.

Diogenes syndrome

• Diogenes syndrome is severe self-neglect, domestic squalor, hoarding and withdrawal, with no shame and refusal of help.

• It often affects people of good intellect with aloof, independent personalities.

• About half have no other major psychiatric disorder, and it is not an ICD-11 diagnosis.

Assessment

• The Geriatric Depression Scale puts less weight on somatic symptoms than the Patient Health Questionnaire (PHQ-9); a GDS-15 score of about 5 or more prompts fuller assessment.

• Ask directly about suicidal thoughts, intent, plans and access to means, because older men have high suicide rates and highly lethal attempts.

Antidepressant response

• Late-life depression responds less well to antidepressants than depression in younger adults.

• The shortfall is concentrated in vascular depression and the depression-executive dysfunction syndrome.

• No response at 4 weeks warrants a check of diagnosis, adherence, dose and contributors before switching or augmenting.

Choosing an antidepressant

Selective serotonin reuptake inhibitors (SSRIs) are first-line: they match tricyclic efficacy, and fewer people stop them because of adverse effects, though they carry bleeding and hyponatraemia risks.

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• Tricyclics and monoamine oxidase inhibitors lack sertraline's cardiac neutrality.

• Tertiary amine tricyclics (amitriptyline, clomipramine, dosulepin, trimipramine) carry more anticholinergic burden than nortriptyline, and all tricyclics are dangerous in overdose.

• Agomelatine is well tolerated by older adults and does not cause hyponatraemia, but it is hepatotoxic, so check liver function at baseline and at set intervals.

• Over 65, the maximum daily dose is citalopram 20 mg and escitalopram 10 mg because of QT prolongation.

Other treatments

• Offer cognitive behavioural therapy, interpersonal therapy or behavioural activation, adapted for sensory or mild cognitive difficulties; age alone should not restrict access.

• Consider ECT for severe depression needing rapid response, such as life-threatening refusal of food or fluid, or after other treatments fail; older adults often respond well.

Course and relapse prevention

• Continue antidepressants for at least about 12 months after remission in older adults, against 6 months in working-age adults.

• Full recovery from earlier depressive episodes predicts a better long-term course.

Bipolar disorder in later life

Onset and causes

• Most older people with bipolar disorder developed it earlier in life, but a first episode can occur after 60.

• A first manic episode in later life is secondary until proven otherwise.

• Look for cerebrovascular disease, neurodegeneration, thyroid disease, corticosteroids, dopaminergic drugs, alcohol and stimulants.

• Post-stroke mania often involves right-sided brain networks.

Presentation

• Irritability, mixed symptoms and persecutory ideas are often more prominent than elation.

• Cognitive impairment can accompany episodes and persist between them.

Differential diagnosis

Lithium maintenance

• The target serum level in people aged 65 and over is 0.4 to 0.6 mmol/L, lower than the 0.6 to 0.8 mmol/L used in working-age adults.

• The target is lower because older people clear lithium less well through the kidneys and are more sensitive to its neurotoxicity.

• People usually start on 200 mg at night, and levels are taken 12 hours after the dose at least every three months.

• Toxicity shows as new confusion, coarse tremor, ataxia, vomiting or falls, and can occur without a dose change during dehydration or infection.

• Thiazides, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and non-steroidal anti-inflammatory drugs raise lithium levels.

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Acute mania

• Risperidone, olanzapine or quetiapine may be chosen according to frailty, cardiac risk and movement effects.

• Haloperidol is contraindicated in Parkinson's disease and dementia with Lewy bodies.

• Electroconvulsive therapy is an option for prolonged, severe or life-threatening mania; frailty calls for anaesthetic assessment, not automatic exclusion.