What are the signs and symptoms of Lewy body dementia in geriatric patients?

Signs and Symptoms of Lewy Body Dementia

Lewy body dementia presents with four core clinical features: fluctuating cognition with pronounced variations in attention and alertness, recurrent well-formed visual hallucinations, spontaneous parkinsonism (bradykinesia, rigidity, tremor, postural instability), and REM sleep behavior disorder where patients act out their dreams. 1

Core Clinical Features (Essential for Diagnosis)

Fluctuating Cognition

• Characterized by pronounced variations in attention, alertness, and cognitive function occurring over minutes, hours, or days 2, 1
• Manifests as cognitive changes secondary to impairments in attention or somnolence due to variations in alertness 2
• Can be assessed using the Mayo Fluctuations Scale or Clinician Assessment of Fluctuation 2, 3
• Patients may have transient episodes of unresponsiveness related to fluctuations in attention and consciousness 1

Visual Hallucinations

• Recurrent, well-formed, and detailed visual hallucinations are characteristic 2, 1
• Typically involve people, animals, or objects 2, 1
• This symptom is highly specific for Lewy body dementia and strongly suggests alternative pathology when present in suspected Alzheimer's disease 1

Parkinsonism

• Spontaneous extrapyramidal motor symptoms including bradykinesia (slowness of movement), rigidity, tremor, and postural instability 2, 1
• These motor symptoms occur without prior exposure to neuroleptic medications 1
• The timing relative to cognitive symptoms is critical: if dementia appears before or within 1 year of motor symptoms, diagnose dementia with Lewy bodies; if dementia develops after at least 1 year of established Parkinson's motor symptoms, diagnose Parkinson's disease dementia 3

REM Sleep Behavior Disorder

• Patients act out dreams during sleep due to lack of normal muscle paralysis during REM sleep 2, 1
• May precede cognitive symptoms by years, making it an important early warning sign 1
• This is a highly characteristic feature that helps distinguish Lewy body dementia from Alzheimer's disease 1

Supportive Clinical Features

Cognitive Profile

• Particularly severe deficits in attention, executive function, and visuospatial abilities 2, 4
• The Montreal Cognitive Assessment (MoCA) is more valid than the MMSE because it includes items assessing attention and executive functions like working memory 2
• Executive dysfunction is characteristic and involves problems with planning, organization, and complex tasks 1

Autonomic Dysfunction

• Orthostatic hypotension (drop in blood pressure upon standing) 1
• Urinary incontinence 1
• Constipation 1

Additional Neuropsychiatric Symptoms

• Syncope (fainting episodes) 5
• Falls, often related to both motor symptoms and autonomic dysfunction 5
• Depression 5
• Sleep disorders beyond REM sleep behavior disorder 5

Critical Diagnostic Pitfalls to Avoid

• Do not diagnose Alzheimer's disease when core Lewy body dementia features are present, even if amyloid biomarkers are positive, as mixed pathology occurs in over 50% of cases 1, 3
• Avoid traditional antipsychotics due to severe neuroleptic sensitivity that can significantly increase morbidity and mortality 1, 5
• Avoid anticholinergic medications as they exacerbate dementia symptoms 5
• Recognize that symptoms can vary significantly between patients and over time within the same individual, making diagnosis challenging 6

Pathophysiological Context

• Lewy body dementia is characterized by abnormal accumulation of α-synuclein protein within inclusions called Lewy bodies, as well as α-synuclein-immunoreactive neurites 2, 1
• Disease progression typically begins in the medulla oblongata, pontine tegmentum, and olfactory system, followed by involvement of the substantia nigra and other deep gray nuclei, and finally deposition in the cortex 2, 1
• Neocortical (diffuse) Lewy body disease is considered an adequate explanation for cognitive impairment or dementia 2, 3