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Dementia is a clinical syndrome where there is progressive and widespread impairment of mental function. There are a number of types of dementia, with Alzheimer's disease being the most common. Dementia with Lewy bodies (DLB) is varyingly quoted as the second or third most common type of dementia, and shares characteristics with Alzheimer's disease and Parkinson's disease.
This type of dementia is characterised by eosinophilic intracytoplasmic neuronal inclusion bodies (Lewy bodies) in the brainstem and neocortex.
There is a spectrum of Lewy body disorders, which may overlap, that include DLB, Parkinson's disease and Parkinson's disease-associated dementia.
DLB is a common type of dementia. Incidence and prevalence figures vary widely, but a recent review in the UK found the incidence to be around 4% of new cases of dementia.It found DLB to account for 4.2% of all cases of dementia diagnosed in the community, and 7.5% of those diagnosed in secondary care.
- Dementia is usually the presenting feature, with memory loss, decline in problem solving ability and spatial awareness difficulties.
- Characteristically there are fluctuating levels of awareness and attention.
- Signs of mild Parkinsonism (tremor, rigidity, poverty of facial expression, festinating gait). Falls frequently occur.
- Visual hallucinations.
- Sleep disorders including rapid eye movement sleep disorder, restless legs syndrome, nocturnal cramps.
- Fainting spells.
Criteria for diagnosis of probable DLB:
- Presence of dementia.
- Two of the three core features:
- Fluctuating attention and concentration.
- Recurrent well-formed visual hallucinations.
- Spontaneous Parkinsonism.
- In the absence of two core features, the diagnosis of probable DLB can also be made if there is dementia along with one core feature and at least one suggestive feature. Suggestive features include:
- Rapid eye movement (REM) sleep behaviour disorder.
- Severe neuroleptic sensitivity.
- Low dopamine transporter uptake in basal ganglia demonstrated by single photon emission computed tomography (SPECT) or positron emission tomography (PET) imaging (see 'Investigations', below).
Possible DLB can be diagnosed where there is dementia plus one core or suggestive feature.
Clinical cognitive assessment is made using one of the standardised tools mentioned by National Institute for Health and Care Excellence (NICE) or Scottish Intercollegiate Guidelines Network (SIGN) guidance:[3, 5]
- Mini Mental State Examination (MMSE).
- 6-item Cognitive Impairment Test (6-CIT).
- General Practitioner Assessment of Cognition (GPCOG).
- 7 Minute Screen (7MS).
- Standard informant interviews may help improve sensitivity (eg, the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE).
- Other forms of dementia, especially dementia in Parkinson's disease or dementia in progressive supranuclear palsy. Normally in dementia associated with Parkinson's disease, the movement disorder has been present for at least a year before the onset of dementia.
- Intracranial tumours.
- Cerebrovascular events.
- Diagnosis is usually a clinical one.
- Basic dementia screen:
- Routine haematology - FBC, ferritin, vitamin B12, folate.
- Biochemistry (including electrolytes, calcium, glucose, and renal and liver
- Midstream specimen of urine (MSU).
- CXR and ECG where clinically indicated.
- CT or MRI scan where indicated to exclude other causes of dementia.
- 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 patients with suspected DLB.SPECT and PET show decreased dopamine transporter uptake.
- Metaiodobenzylguanidine (MIBG) scintigraphy may be of value as a diagnostic tool for differentiation between Lewy body disease and Parkinsonian syndromes or other movement disorders with Parkinsonism. This method may also provide a tool for differentiating between DLB and Alzheimer's disease.
- Refer to a specialist with expertise in differential diagnosis - so that DLB 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 is 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).
- Non-pharmacological interventions should be tailored to the individual person's preferences and abilities as well as to local resources, and adapted depending on response. These include:
- Cognitive stimulation programmes
- Multisensory stimulation
- Music therapy
- Art therapy
- Structured exercise programmes
- Animal-assisted therapy
- 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), and arrange daycare, day centre attendance, relief admissions, etc.
- Driving is a very complex task and people who have DLB must not drive. There may be lack of insight and a reluctance to lose mobility and freedom.
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 may be increased. Where these are used, careful monitoring for sensitivity reactions should take place.
- Anti-Parkinsonian treatment may also worsen psychosis.
- NICE and SIGN guidelines advise that cholinesterase inhibitors - eg rivastigmine - at daily doses of 6 mg and above, can be helpful in treating cognitive decline in people with DLB. However the most recent Cochrane review suggests the evidence of benefit remains unclear.
As with other types of dementia, DLB is progressive, and shortens lifespan. It progresses gradually over the course of years. Average survival from onset is 5-8 years. Rate of cognitive decline appears to be similar for DLB and Alzheimer's disease.
Further reading and references
; Dementia with lewy bodies. Semin Neurol. 2007 Feb27(1):42-7.
; Alzheimers Research UK, January 2014
; The prevalence and incidence of dementia with Lewy bodies: a systematic review of population and clinical studies. Psychol Med. 2014 Mar44(4):673-83. doi: 10.1017/S0033291713000494. Epub 2013 Mar 25.
; NICE Clinical Guideline (November 2006, last updated September 2016)
; Consensus guidelines for the clinical and pathologic diagnosis of dementia with Lewy bodies (DLB): report of the Consortium on DLB International Workshop. J Alzheimers Dis. 20069(3 Suppl):417-23.
; Scottish Intercollegiate Guidelines Network - SIGN (Feb 2006)
; Recent developments in innervation imaging using Neurol Sci. 2010 Mar 10.
; Cholinesterase inhibitors for dementia with Lewy bodies, Parkinson's disease dementia and cognitive impairment in Parkinson's disease. Cochrane Database Syst Rev. 2012 Mar 143:CD006504. doi: 10.1002/14651858.CD006504.pub2.
; Differences in clinical course between dementia with Lewy bodies and Alzheimer's disease. Eur J Neurol. 2009 Feb16(2):212-7. doi: 10.1111/j.1468-1331.2008.02388.x.
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