Lewy body dementia is a broad term that encompasses both dementia with Lewy bodies (DLB) and Parkinson’s disease dementia, and the three conditions can be seen residing on a continuum of Lewy body disease. The Lewy bodies, named after Frederich H. Lewy, who made the original discovery of them in 1912, are distinctive brain abnormalities associated with DLB. α-synuclein is a protein that accumulates abnormally in Lewy bodies. Lewy bodies change certain brain chemicals, and these changes may have an impact on thinking, behavior, moving, and feeling.

Lewy body dementia is the second most common prevalent degenerative dementia, after Alzheimer's disease. DLB has the signature appearance of the presence of Lewy bodies in the limbic system, brain stem, and neocortical regions of the brain. The incidence rate for DLB is between 0.5 and 1.6 per 1000 person-years, while the prevalence ranges from 0.02 to 63.5 per 1000 people. The recent global raise in life expectancy is a contributing factor to its prevalence. DLB is more common in men than in women. With increasing age, DLB patients make up about 5% of all dementia cases in the elderly population.

Dementia with Lewy bodies (DLB) is a type of progressive dementia that leads to a decline in thinking, reasoning, and independent function.

Symptoms

Early Lewy body dementia symptoms are usually misdiagnosed as Parkinson's or Alzheimer's manifestations. DLB can show symptoms both independently and in conjunction with other brain disorders. The presenting symptoms of DLB can be broadly categorized as cognitive impairment, behavioral/psychiatric phenomena, and physical symptoms.

Cognitive impairment:

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• Mild cognitive impairment (intermediate between normal cognitive function and dementia)

• The primary clinical indicators of DLB include cognitive alterations and varying degrees of attentiveness and alertness.

Behavioral/psychiatric phenomena:

• Rapid eye movement (REM) sleep behavior disorder (RBD) (enactment of dreams such as punching, kicking, and shouting out, which frequently causes harm).

• Visual hallucinations

• Apathy (reduced initiative and motivation), anxiety, and depression are present at the initial stage and tend to persist over time.

• Delirium (confused thinking and a lack of consciousness).

Physical symptoms:

• Signs and symptoms of parkinsonism such as rigid muscles, slow movement, walking difficulty, and tremors.

• Hyposmia (decreased sense of smell)

• Autonomic dysfunction: The common presenting symptoms include orthostatic hypotension, urinary incontinence, erectile dysfunction, constipation, gastroparesis, and seborrhea (excessive discharge of sebum).

• Extreme sensitivity to antipsychotic medications.

Diagnosis

A complete physical examination, an accurate clinical history, and a timeline of symptoms are the key factors of the DLB diagnosis. The importance of cognitive testing cannot be overstated, even though there may not be any or only minor cognitive abnormalities in the early stages of the disease. Imaging also plays a crucial role in establishing a firm diagnosis. It is recommended to use a combination of imaging modalities to increase the accuracy of the diagnosis, including computed tomography, magnetic resonance imaging, dopamine uptake imaging, cardiac sympathetic degeneration, fluorodeoxyglucose positron emission tomography (PET), perfusion single-photon emission computed tomography (SPECT) imaging, amyloid PET imaging, and electroencephalogram (EEG).

Management

Management of DLB patients is challenging due to the lack of disease-modifying therapies and most DLB patients only receive symptomatic care. Patients with DLB may benefit from using acetylcholinesterase inhibitors, antipsychotics, antidepressants, electroconvulsive therapy, and psychostimulants. Melatonin, ropinirole, pramipexole, gabapentin, pregabalin, rotigotine, and other drugs can be used to treat sleep disorders in DLB patients. Levodopa, amantadine, rotigotine, and selegiline are medications that can be used to treat a variety of motor or movement disorders. Midodrine, fludrocortisone, and droxidopa are the drugs that are utilized most frequently when pharmacological therapy is necessary for autonomic dysfunction. Additionally, numerous cutting-edge treatments are being researched.

Some aspects, such as challenges with basic activities of daily living, the existence of depression, apathy, hallucinations, and autonomic dysfunction in DLB patients, are linked to a lower quality of life. Given the poor prognosis and high socioeconomic burden of DLB, we should consider the health-related quality of life as one of the outcome measurements while developing new drugs or therapies for DLB.