Background

Dementia with Lewy bodies (DLB) is the second commonest cause of degenerative dementia in older people, responsible for 10-15% of all cases. In addition, dementia develops in up to 80% of people with Parkinson's disease, often known as Parkinson's disease dementia (PDD). PDD and DLB are commonly grouped together as Lewy body dementia (LBD) because they share many clinical features, have similar underlying neurobiology and respond to similar management approaches. LBD affects around 160,000 people in the UK and, like other dementias, prevalence will approximately double over the next 30 years. 

Whilst diagnostic criteria for Alzheimer’s disease (AD) have been reasonably well developed over the last 30 years, those for LBD have only relatively recently been described and validated. As such, they are not yet optimally applied in routine clinical practice and because of this LBD remains under-detected in clinical practice, even in specialist secondary care NHS settings. There are several reasons for this: 

1) key symptoms of LBD such as hallucinations, fluctuation and parkinsonism are often not properly assessed in memory and dementia services; 

2) there remains a lack of general knowledge regarding the clinical features and management of LBD in comparison to the other two main causes of dementia, AD and vascular dementia (VaD); 

3) in neurology and geriatric medicine services, where most people with Parkinson's disease are seen, there is a lack of awareness of cognitive symptoms so diagnosis of dementia is either not made or delayed. 

Because of the scale of the problem and a number of LBD cases not appropriately recognised and managed, there is a need for improved methods for case detection, and clear evidence-based guidelines for management. Optimal management of DLB is important because such subjects often receive antipsychotic medication for psychiatric and behavioural symptoms, yet these are contra-indicated because of a potentially fatal sensitivity reaction (in addition to the other well-known risks of antipsychotics in those with dementia). Parkinsonism is often inadequately treated in DLB, though treatments can sometimes be effective providing they are started in low dose and titrated carefully. Sleep disturbance, falls, associated depression and autonomic dysfunction are other key features of LBD which are uncommon in other dementias, yet have effective and specific management options available that can significantly improve quality of life for patient and carer. 

By developing, validating and implementing the assessment and management tool for LBD in both dementia assessment services and neurology services, we will significantly impact on improving diagnosis of LBD and patient management, with direct benefit to patients.

The DIAMOND-Lewy programme is funded by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research Programme (DTC-RP-PG-0311-12001).

The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.