Dementia with Lewy Bodies (DLB)

See other related dementia articles.

This is the second commonest form of neurodegenerative dementia after Alzheimer's disease; characterised by eosinophilic intracytoplasmic neuronal inclusion bodies (Lewy-bodies) in brainstem and neo-cortex. It accounts for about 15-20% of patients with dementia,¹ and there are an estimated 100,000 cases in the UK.²

The international consensus criteria should be used.⁵ Accurate diagnosis is important as it affects management (see below).

Two of the three core diagnostic features are required for "probable DLB"; one for "possible DLB":²

• Fluctuating confusion
• Persistent visual hallucinations
• Spontaneous parkinsonism.

Standard informant interviews may help improve sensitivity (eg Informant Questionnaire on Cognitive Decline in the Elderly: IQCODE).⁶

Other forms of dementia, especially dementia in Parkinson's Disease or dementia in progressive supranuclear palsy; intracranial tumours, cerebrovascular events.

• Diagnosis is usually a clinical one.
• Dopaminergic iodine-123-radiolabelled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (FP-CIT) SPECT can be used to help establish the diagnosis in patents with suspected dementia with Lewy bodies (DLB).¹

• Refer to a specialist with expertise in differential diagnosis - so that Lewy body dementia can be identified using the appropriate criteria and investigations.
• Nominate a key worker, and agree a mental health care management plan with the principal carer. Record in the patient's record.
  Care plans should address patient's activities of daily living (ADL), particularly trying to maximise their independence. The aim to keep the patient in as familiar and unchanging an environment as possible, building in exercise and occupational therapy, and some flexibility to cope with fluctuating abilities.
• Identify and involve all carers as much as possible, and ensure they understand both the diagnosis and prognosis (prepare the spouse for the day when the patient no longer recognises loved ones).
• Try to involve the psychiatric social worker and carer support workers early. They can help with the initial risk assessment, arrange appropriate financial support (allowances etc.); arrange day care, day centre attendance, relief admissions etc..
• Driving is a very complex task and people who are demented must not drive. There may be lack of insight and reluctance to loose mobility and freedom.

Medication

Behavioural and psychotic symptoms may need assessment by psychogeriatrician, who may also assess whether drug treatment is appropriate to prevent deterioration.

• Avoid neuroleptic drugs for psychiatric and behavioural problems - these commonly induce severe sensitivity reactions in DLB patients - motor and mental impairment is worsened and mortality is increased threefold.^5,7
• Anti-parkinsonian treatment may also worsen psychosis.
• Cholinesterase inhibitors - eg rivastigmine, at daily doses of 6 mg and above, can be helpful in treating cognitive decline in people with dementia with Lewy bodies.¹

Monitor for the emergence of severe untoward reactions, particularly neuroleptic sensitivity reactions (eg worsening extrapyramidal features and/or severe physical deterioration following prescription antipsychotic drugs for which there is no other apparent cause).⁸