Dementia with Lewy bodies

A neurodegenerative disorder with parkinsonism, progressive cognitive decline, prominent executive dysfunction, and visuospatial impairment.

Core clinical features include: recurrent visual hallucinations; cognitive fluctuations; REM sleep behaviour disorder; and one or more spontaeous cardinal features of parkinsonism: bradykinesia, rest tremor, or rigidity. Supportive clinical features include sensitivity to antipsychotic agents, postural instability and falls, syncope, autonomic dysfunction, delusions and non-visual hallucinations, apathy, anxiety, and depression.

Diagnosis is made clinically and can only be confirmed pathologically by the presence of Lewy bodies. Many patients have concomitant Alzheimer's disease (AD)-type pathology.

Meta-analyses support the use of cholinesterase inhibitors for the cognitive and the neurobehavioural symptoms. Memantine may be of some value in the treatment of dementia and behavioural symptoms.

The use of antipsychotic medication must be minimised due to the increased sensitivity to these medicines' adverse effects, including increased mortality.

Levodopa/carbidopa can be used for the motor symptoms, though adverse effects may be restrictive and response limited; clonazepam is effective for REM sleep behavioural disorder.

Essential for a diagnosis of dementia with Lewy bodies (DLB) is dementia, defined as a progressive cognitive decline of sufficient magnitude to interfere with normal social or occupational functions, or with usual daily activities. DLB is characterised by the following core clinical features (the first 3 typically occur early, and may persist throughout the course): fluctuating cognition; recurrent visual hallucinations; REM sleep behaviour disorder; and one or more spontaneous cardinal symptoms of parkinsonism: bradykinesia, rest tremor, or rigidity. Prominent or persistent memory impairment may not necessarily occur in the early stages but is usually evident with progression. Deficits on tests of attention, executive function, and visuoperceptual ability may be especially prominent and occur early.[1]McKeith IG, Boeve BF, Dickson DW, et al. Diagnosis and management of dementia with Lewy bodies: fourth consensus report of the DLB Consortium. Neurology. 2017 Jul 4;89(1):88-100. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5496518/ http://www.ncbi.nlm.nih.gov/pubmed/28592453?tool=bestpractice.com Disease course is progressive, although treatment may help some cognitive, sleep, motor, and behavioural symptoms. DLB should be distinguished from neurocognitive disorder associated with Parkinson's disease, although there are areas of clinical overlap.

In the DSM-5, DLB is classified as a major neurocognitive disorder with Lewy bodies.[2]American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 5th edition. (DSM-5). Washington, DC: American Psychiatric Publishing; 2013.