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Dementia with Lewy bodies (DLB) is the second most common form of primary neurodegenerative dementia after Alzheimer's disease.

Pathogenesis

It is characterised by eosinophilic intracytoplasmic neuronal inclusion bodies (Lewy bodies) in the brainstem and neocortex.

There is a spectrum of Lewy body disorders that includes not only dementia with Lewy bodies (DLB), Parkinson's disease and Parkinson's disease-associated dementia but also Lewy body dysphagia and autonomic failure with Lewy bodies.

Epidemiology

It accounts for about 15-20% of patients with dementia,¹ and there are an estimated 100,000 cases in the UK.²
Approximately 75% of older people with Parkinson's disease will develop dementia after 10 years.³

Diagnosis

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

Two of the three core diagnostic features are required for 'probable' dementia with Lewy bodies (DLB); one for 'possible' DLB:²

• Fluctuating confusion
• Persistent visual hallucinations
• Spontaneous Parkinsonism

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

Differential diagnosis

• Other forms of dementia, especially dementia in Parkinson's disease or dementia in progressive supranuclear palsy
• Intracranial tumours
• Cerebrovascular events

Investigations

• Diagnosis is usually a clinical one.
• Dopaminergic iodine-123-radiolabelled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (FP-CIT) single photon emission computed tomography (SPECT) can be used to help establish the diagnosis in patients with suspected dementia with Lewy bodies (DLB).¹
• Metaiodobenzylguanidine (MIBG) scintigraphy is a valuable diagnostic tool for differentiation between Lewy body disease and Parkinsonian syndromes or other movement disorders with Parkinsonism.⁷ This method may also provide a tool for differentiating between DLB and Alzheimer's disease.

Management

• 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 the key worker in the patient's record.
  • Care plans should address the 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 have dementia with Lewy bodies (DLB) must not drive. There may be lack of insight and reluctance to lose mobility and freedom.

Medication

Behavioural and psychotic symptoms may need assessment by a 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.^5,8
• Anti-Parkinsonian treatment may also worsen psychosis.
• Cholinesterase inhibitors - e.g. rivastigmine, at daily doses of 6 mg and above, can be helpful in treating cognitive decline in people with DLB.¹

Monitoring

Monitor for the emergence of severe untoward reactions, particularly neuroleptic sensitivity reactions - e.g. worsening extrapyramidal features and/or severe physical deterioration following prescription antipsychotic drugs, for which there is no other apparent cause.⁹

Document references

1. Management of patients with dementia, SIGN (Feb 2006)
2. McKeith IG, O'Brien JT, Ballard C; Diagnosing dementia with Lewy bodies. Lancet. 1999 Oct 9;354(9186):1227-8.
3. Aarsland D, Andersen K, Larsen JP, et al; Prevalence and characteristics of dementia in Parkinson disease: an 8-year prospective study. Arch Neurol. 2003 Mar;60(3):387-92. [abstract]
4. Crystal HA; Dementia with Lewy Bodies, eMedicine, Dec 2009.
5. McKeith IG, Galasko D, Kosaka K, et al; Consensus guidelines for the clinical and pathologic diagnosis of dementia with Lewy bodies (DLB): report of the consortium on DLB international workshop. Neurology. 1996 Nov;47(5):1113-24. [abstract]
6. Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) - Copies downloadable from website (paper format).
7. Treglia G, Cason E, Gabellini A, et al; Recent developments in innervation imaging using Neurol Sci. 2010 Mar 10. [abstract]
8. McKeith I, Fairbairn A, Perry R, et al; Neuroleptic sensitivity in patients with senile dementia of Lewy body type. BMJ. 1992 Sep 19;305(6855):673-8. [abstract]
9. Dementia: Supporting people with dementia and their carers in health and social care, NICE Clinical Guideline (2006)

Internet and further reading

• Weisman D, McKeith I; Dementia with lewy bodies. Semin Neurol. 2007 Feb;27(1):42-7. [abstract]
• Friedrich H. Lewy whonamedit.com; German-American neurologist, born January 28, 1885, Berlin; died 1950.
• Summary of Product Characteristics - Exelon® (rivastigmine hydrogen tartrate) Novartis Pharmaceuticals UK Ltd. Electronic Medicines Compendium. Text revised March 2009. Accessed May 2009.

Acknowledgements