Lewy body dementia

Lewy body dementia
Field	Neurology, Psychiatry

Lewy body dementia. It is a progressive neurodegenerative disease characterized by the abnormal aggregation of alpha-synuclein protein into Lewy bodies within the brain. The condition encompasses both dementia with Lewy bodies and Parkinson's disease dementia, sharing core clinical features. It is the second most common type of degenerative dementia after Alzheimer's disease.

Signs and symptoms

Core clinical features include fluctuating cognition, recurrent visual hallucinations, and spontaneous motor features of parkinsonism. Patients often experience rapid eye movement sleep behavior disorder, severe sensitivity to antipsychotic medications, and autonomic dysfunction. Cognitive fluctuations can vary dramatically, affecting attention and alertness throughout the day. Additional neuropsychiatric symptoms may include apathy, anxiety, and delusions.

Causes and pathophysiology

The primary pathological hallmark is the presence of Lewy bodies, which are abnormal aggregates of alpha-synuclein protein, within the cerebral cortex, limbic system, and brainstem. This pathology disrupts several neurotransmitter systems, notably causing a profound deficiency of acetylcholine and dopamine. While most cases are sporadic, genetic risk factors include variants in the GBA gene and the APOE ε4 allele. The disease often coexists with Alzheimer's disease pathology, including amyloid plaques and neurofibrillary tangles.

Diagnosis

Diagnosis is primarily clinical, based on established criteria from consortia like the DLB Consortium. Key tools include neuropsychological testing and neuroimaging such as DaTscan to assess dopaminergic transporter loss. Supportive biomarkers include reduced uptake on iodine-123-metaiodobenzylguanidine cardiac scintigraphy and polysomnography confirmation of REM sleep behavior disorder. Differential diagnosis is crucial to distinguish it from Alzheimer's disease, Parkinson's disease, and vascular dementia.

Management

Management is multidisciplinary and symptomatic, involving neurologists, psychiatrists, and occupational therapists. Cholinesterase inhibitors like rivastigmine and donepezil are first-line for cognitive and neuropsychiatric symptoms. For parkinsonism, low-dose levodopa may be used cautiously. Extreme caution is required with typical antipsychotics due to high risk of severe sensitivity reactions. Non-pharmacological approaches include physical therapy, sleep hygiene interventions, and caregiver education through organizations like the Lewy Body Dementia Association.

Prognosis and epidemiology

The disease has a progressive course, with median survival from diagnosis ranging from five to eight years. It is estimated to affect over 1 million individuals in the United States and accounts for 10-15% of all dementia cases. Incidence increases significantly with age, with most patients diagnosed after age 50. The prognosis is generally poorer than for Alzheimer's disease alone, due to more rapid functional decline and higher rates of hospitalization and institutionalization.

History and society

The condition is named after Dr. Friedrich H. Lewy, who first described the cytoplasmic inclusions in 1912 while working in Alois Alzheimer's laboratory. Clinical recognition as a distinct dementia entity grew significantly in the 1990s, leading to the first consensus diagnostic criteria. Increased awareness has been driven by advocacy from the Lewy Body Dementia Association and the disclosure of diagnoses in public figures like Robin Williams. Research efforts are coordinated by entities such as the National Institute of Neurological Disorders and Stroke.

Category:Dementia Category:Neurodegenerative disorders