7.4 Physical disease and psychiatric presentation in later life

How physical and psychiatric illness interact

• Physical disease can act on the brain directly (stroke, endocrine illness), through its treatment (corticosteroids, dopaminergic drugs), or through loss, pain and dependence.

• Depression in turn worsens nutrition, mobility, adherence and self-care.

• Normal sadness about illness varies with circumstances and allows enjoyment, but no single pattern excludes depression, so assess persistence, anhedonia, guilt and suicidality.

Normal ageing

• Renally excreted drugs accumulate in older people because glomerular filtration declines.

Blood results that mislead

• A normal serum creatinine can hide a reduced filtration rate, because less muscle produces less creatinine.

• Low albumin lowers measured total calcium (pseudohypocalcaemia) and raised albumin raises it, because much plasma calcium is albumin bound while ionised calcium stays normal.

Prescribing hazards in older people

• Polypharmacy, the cumulative effect of many regular medicines, causes falls and gait disturbance.

• Antidepressants are the psychotropic class most strongly linked to falls, and selective serotonin reuptake inhibitors (SSRIs) raise falls risk about as much as tricyclics, despite their cardiac and anticholinergic advantages.

• SSRIs raise upper gastrointestinal bleeding risk by depleting platelet serotonin and impairing aggregation, adding to the risk from aspirin, non-steroidal anti-inflammatory drugs (NSAIDs) and anticoagulants.

• Ginkgo biloba raises bleeding risk additively, so people taking an anticoagulant or antiplatelet drug should avoid it.

• Aminophylline, theophylline and acetazolamide reduce proximal tubular sodium reabsorption, which increases lithium excretion and lowers the serum level.

• Thiazides, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers and NSAIDs raise the serum lithium level.

• Older age is a strong, dose-independent risk factor for tardive dyskinesia, raising its incidence five- to six-fold compared with younger adults on the same antipsychotic.

• Benzodiazepines can cause paradoxical disinhibition in older adults, with excitement, hostility, vivid dreams and sexual disinhibition alongside sedation.

Antipsychotics, stroke and the heart

• Antipsychotics in older adults roughly double the rate of stroke and other cerebrovascular events (rate ratio about 1.7, confidence interval about 1.6 to 1.9), with a similar excess for typical and atypical drugs.

• Douglas and Smeeth (2008) found a rate ratio of about 2.3 for atypicals.

• In dementia, antipsychotics raise stroke risk two- to threefold, an absolute risk near 1%, with the excess concentrated early in treatment.

• In dementia trials, stroke risk with risperidone and olanzapine was about three times that with placebo.

• UK regulatory warnings on excess mortality and stroke in dementia now cover all first- and second-generation antipsychotics, not only the two drugs first named in 2004.

• The National Institute for Health and Care Excellence (NICE) advises short-term, low-dose haloperidol for agitation in delirium when distress or risk to others persists after de-escalation fails, provided the QTc is normal and there is no parkinsonism.

• Benzodiazepines are kept for withdrawal delirium.

Psychiatric effects of medicines for physical illness

• Ask about suicidal thoughts with any antiepileptic.

• Oxybutynin is antimuscarinic and crosses the blood-brain barrier readily, so it harms people with existing cognitive impairment most.

Parkinson's disease

• Depression, anxiety, apathy and psychosis are common, and anxiety or low mood may precede the motor diagnosis or worsen in "off" periods.

• Apathy is reduced initiation and motivation, sometimes without sadness or guilt, so assess for coexisting depression.

• Dementia risk rises with age and with duration of Parkinson's disease.

Impulse control disorders

• Dopamine agonists acting at D2 and D3 receptors, such as pramipexole, are the drugs most strongly linked to impulse control disorders, in Parkinson's disease and in restless legs syndrome.

• They act by stimulating the mesolimbic reward pathway, and risk rises with dose.

• Levodopa has a weaker, dose-related association.

• The behaviours are gambling, hypersexuality, compulsive buying and binge eating, affecting about one in six to one in five agonist-treated patients.

• Punding is repetitive, non-goal-directed activity.

• Ask before treatment and at each review, with collateral history, because patients may not see the link or may not disclose it.

• Reduce the agonist gradually under specialist guidance, because abrupt withdrawal can cause a severe withdrawal syndrome.

Psychosis and other levodopa effects

• Visual experiences range from sensed presence or movement at the edge of vision to formed hallucinations and delusions.

• Assess new symptoms for delirium, and review provoking drugs with a Parkinson's specialist; well-tolerated hallucinations may need no drug.

• NICE suggests considering quetiapine where there is no cognitive impairment, and offering clozapine with its monitoring when standard treatment fails.

• Avoid conventional antipsychotics and risperidone, which worsen motor function.

Stroke

Post-stroke depression

• Routine SSRI treatment after stroke lowers the incidence of new depression but raises fracture risk and does not improve motor or functional recovery.

• In placebo-controlled prevention trials, escitalopram, sertraline, fluoxetine and mirtazapine reduced post-stroke depression, but mianserin did not.

• SSRIs, serotonin and noradrenaline reuptake inhibitors and serotonergic tricyclics all block the platelet serotonin transporter.

• With warfarin, fluvoxamine and fluoxetine inhibit its clearing enzymes, carbamazepine induces them, and amitriptyline is also less suitable.

Emotionalism

• Pseudobulbar affect is brief, stereotyped, uncontrollable laughing or crying that does not match the felt mood, arising from neurological disease.

• Post-stroke emotionalism is brief, poorly controlled crying or laughing that can coexist with depression.

• An SSRI is the first-line drug for emotionalism, with trial support; treat when it causes distress or limits rehabilitation.

• Stroke may also cause executive dysfunction, apathy, rigidity or disinhibition, judged against premorbid behaviour.

Acute neurological presentations

• Unenhanced computed tomography (CT) of the head is the first test for suspected subarachnoid haemorrhage, being fast and nearly fully sensitive in the first hours.

• Lumbar puncture is kept for a normal CT with persisting suspicion.

The forehead is spared in upper motor neuron weakness because the upper face has bilateral cortical supply.

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Sensory impairment

• Hearing and visual loss can mimic cognitive failure or suspiciousness, so check aids and adapt communication before interpreting test scores.

• Charles Bonnet syndrome is formed visual hallucinations, often of people, animals or patterns, arising from sight loss in clear consciousness, with insight kept and no cognitive or psychiatric disorder.

• Preserved insight alone does not exclude delirium or Lewy body disease.

• Manage it with explanation, better vision and reassurance; antipsychotics have little evidence and their risks usually outweigh benefit.

Reversible contributors to dementia

A treatable cause more often overlaps with neurological disease than fully explains it.

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• Other causes include hyperparathyroidism, hypercalcaemia, uraemia, hepatic encephalopathy, neurosyphilis, human immunodeficiency virus (HIV) disease and autoimmune or limbic encephalitis.

• A rapid course, early gait or sphincter change, focal signs, systemic symptoms or a link to a drug or injury should widen the work-up.