Dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is a neurodegenerative disorder with parkinsonism, progressive cognitive decline, prominent executive dysfunction, behavioural and sleep disturbances, and visuospatial impairment.

Core clinical features are: cognitive fluctuations; recurrent visual hallucinations; rapid eye movement (REM) sleep behaviour disorder; and one or more spontaneous cardinal motor 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-type pathology.

Treatment requires a multidisciplinary approach, with emphasis on behavioural and psychological symptoms. This includes both non-pharmacological/behavioural and pharmacological interventions, as well as supportive care. The main goal of treatment is to improve or stabilise cognition, behaviour, and activities of daily living, and to maintain safety.

First-line pharmacological treatment for cognitive impairment and behavioural symptoms is cholinesterase inhibitors. Clonazepam or melatonin is effective for REM sleep behavioural disorder. Levodopa/carbidopa can be used for motor symptoms, although adverse effects may be restrictive and response limited.

The use of antipsychotic drugs for acute management of behavioural disturbance should be avoided as far as possible because of the risk of increased mortality. Low-dose atypical antipsychotics may be used with caution if necessary.

Dementia is 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 motor 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 [2]Hemminghyth MS, Chwiszczuk LJ, Rongve A, et al. The cognitive profile of mild cognitive impairment due to dementia with Lewy bodies - an updated review. Front Aging Neurosci. 2020 Dec 23;12:597579. https://www.frontiersin.org/articles/10.3389/fnagi.2020.597579/full http://www.ncbi.nlm.nih.gov/pubmed/33424578?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-TR (Diagnostic and Statistical Manual of Mental Disorders, 5th ed., text revision), DLB is classified as a major neurocognitive disorder with Lewy bodies.[3]American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 5th ed., text revision (DSM-5-TR). Washington, DC: American Psychiatric Publishing; 2022.