Described for the first time in late 1980s, Dementia with Lewy Bodies (DLB) is a gradually progressive neurodegenerative disorder with insidious onset. Histopathologically, the hallmark feature of DLB is the presence of Lewy bodies in the cerebral cortex.

Fluctuating cognition is a core feature. Fluctuation is seen in consciousness, memory, language, and visuospatial abilities; and can occur within hours or days. It is sometimes indistinguishable from delirium. Studies have suggested at profound cholinergic deficit as the cause for the fluctuating consciousness.

Parkinsonism occurring at least 1 year after the onset of dementia is a feature of DLB. This can also occur concurrent to, or shortly before cognitive decline; however, it should not antecede the dementia by more than 1 year.

Among the parkinsonian features, rigidity and gait abnormalities are more common than tremor. Parkinsonism occurs due to dopaminergic deficiency in the substantia nigra.

Up to 50% of the patients with DLB demonstrate severe sensitivity to neuroleptic drugs such as haloperidol and chlorpromazine. Features of neuroleptic sensitivity include sedation, rigidity, postural instability, and in some cases, even rapid deterioration and death. This is because the extensive loss of dopaminergic and cholinergic neurons due to neurodegeneration renders affected individuals more susceptible to the antidopaminergic and anticholinergic effects of neuroleptics.

Non-visual hallucinations, particularly auditory hallucinations and delusions, and specifically of a persecutory nature, are common.

DLB is a risk factor for falls. This probably due to postural instability secondary to parkinsonism, autonomic dysregulation, and fluctuating cognition.