14th February 2025

Dementia

Dementia

Overview of dementia

Dementia describes a syndrome of cognitive and functional symptoms, rather than a specific disease. Mild cognitive impairment (MCI) refers to cognitive impairment not yet impacting functional status. Patients with MCI are over five times more likely to develop dementia than those without.

Presentation and diagnosis of dementia

As well as hearing the patient’s own account, a collateral history is essential. Timeline is important: gradual onset points to a degenerative cause whereas sudden onset points to vascular or other acute causes.

Cognitive symptoms may include deficits in memory, attention or language, e.g. word-finding difficulties. Functional symptoms are generally described as a reduced ability to carry out activities of daily living (ADL).

Differential diagnosis

There is a wide differential diagnosis in dementia. This includes medical conditions that affect organs or systems other than the brain, sometimes referred to as organic causes. This is a misnomer originating in mind-body dualism, as clearly the brain is an organ.

Over 10% of dementia presentations are caused by reversible conditions; a careful approach to history, physical examination and investigations is essential to look for these. In particular, acute or subacute presentation (days to months) should raise suspicion for medical conditions originating outside the brain, including:

• Infection: neurosyphilis, tuberculous meningitis, HSV encephalitis, Lyme disease, CJD
• Inflammation: multiple sclerosis, systemic lupus erythematosus, sarcoidosis, Sjögren’s, limbic encephalitis
• Endocrine: thyroid, pituitary disease, parathyroid disease, Cushing’s
• Metabolic and nutritional: B12 or folate deficiency, uraemia, Wilson’s disease, porphyria
• Traumatic: subdural haematoma, traumatic brain injury
• Toxicity: alcohol, heavy metals, carbon monoxide sequelae, lithium
• Iatrogenic

Neurological and psychiatric differentials include:

• Alzheimer’s disease, vascular dementia, dementia with Lewy bodies, frontotemporal dementia, Korsakoff’s
• Pseudodementia: cognitive and functional deficit due to mental illness such as depression or schizophrenia
• Delirium
• Stroke, normal pressure hydrocephalus (classic triad is urinary incontinence, gait and cognitive disturbance)

Common neuropsychiatric causes of dementia

The dementia subtypes below are common and ordered by prevalence. Mixed dementia refers to dementia caused by two or more underlying aetiologies.

Table 3 Common causes of dementia with key features of the history and examination

Investigations in dementia

Bedside blood tests and imaging are needed to rule out organic causes (see Investigations in delirium).

Cognitive screening tests such as MMSE (Mini Mental State Examination) or ACE (Addenbrooke’s Cognitive Examination) should be completed before specialist referral.

Management of dementia

Non-pharmacological intervention

Management in the early stages of dementia is mainly education for the patient and their relatives or carers, in relation to what can be expected as the condition progresses and the support available.

There are various non-pharmacological interventions, namely therapies and activities aimed at preserving cognition, independence and wellbeing. These are most suited to patients with mild-to-moderate dementia.

As a progressive, irreversible condition, advance care planning is important at all stages. Patients should be counselled on options such as: Lasting Power of Attorney (LPA), advance statement (wishes, preferences, values), advance decisions to refuse treatment, and, when near end of life, their preferred place of death.

Pharmacological intervention

Table 4 Pharmacological interventions for different causes of dementia

It is important to deprescribe medications that may worsen cognition, especially those with anticholinergic effects. Common examples include:

• Antimuscarinics: tolterodine, darifenacin, solifenacin, oxybutynin, procyclidine
• Antipsychotics: olanzapine, chlorpromazine
• Tricyclic antidepressants: amitriptyline, nortriptyline
• Antihistamines: chlorphenamine, cetirizine, cyclizine, promethazine

Patients with dementia may have significant distress and pose a risk to themselves or others. Reversible causes should always be explored first, e.g. pain, delirium or environment. If necessary and safe, acute pharmacological measures may be required, with the lowest effective dose. Note that antipsychotic use is off label, and that these drugs should be avoided in patients with Parkinson’s disease or Lewy body dementia.

References

• National Institute for Health and Care Excellence. Dementia: assessment, management and support for people living with dementia and their carers. [Internet]. NICE. 2018 [cited 2022 Jan 15]. Available from: https://www.nice.org.uk/guidance/ng97
• NHS Choices. Symptoms of Dementia – Dementia Guide [Internet]. NHS. 2019 [cited 2022 Jan 15]. Available from: https://www.nhs.uk/conditions/dementia/symptoms/
• Liberty Protection Safeguards: what they are [Internet]. GOV.UK. 2021 [cited 2022 Jan 15]. Available from: https://www.gov.uk/government/publications/liberty-protection-safeguards-factsheets/liberty-protection-safeguards-what-they-are
• Alzheimer’s Society. How many people have dementia and what is the cost of dementia care? [Internet]. Alzheimer’s Society. 2019 [cited 2022 Jan 15]. Available from: https://www.alzheimers.org.uk/about-us/policy-and-influencing/dementia-scale-impact-numbers
• Alzheimer’s Society. What is dementia? [Internet]. Alzheimer’s Society. 2021 [cited 2022 Jan 15]. Available from: https://www.alzheimers.org.uk/about-dementia/types-dementia/what-is-dementia
• Benrimoh D, Pomerleau VJ, Demoustier A, Poulin S, Maltais J-R, Brouillette J, et al. Why We Still Use “Organic Causes”: Results From a Survey of Psychiatrists and Residents. The Journal of Neuropsychiatry and Clinical Neurosciences. 2019 Jan;31(1):57–64
• Gupta A, Tampi R, Taskiran S, Lopez J, Muralee S. Assessment of dementia [Internet]. BMJ Best Practice. 2021 [cited 2022 Mar 1]. Available from: https://bestpractice.bmj.com/topics/en-gb/242