Alzheimer's vs. Delirium: Differences

Alzheimer's Disease vs. Delirium

• Key differences exist between Alzheimer's disease and delirium
• These differences can be seen in their clinical manifestations, disease progression, causative agents, contributing factors, and pathophysiological mechanisms

Clinical Manifestations

• Alzheimer's disease is characterized by:
• Progressive memory loss
• Disorientation
• Confusion
• Impaired problem-solving
• Difficulties with language and judgment
• Behavioral symptoms like irritability, agitation, mood swings, depression, and anxiety
• Delirium manifests as:
• Acute changes in cognition and attention
• Fluctuating levels of consciousness
• Disorganized thinking
• Perceptual disturbances like hallucinations or delusions
• Hyperactive delirium involves restlessness and agitation
• Hypoactive delirium involves lethargy and reduced motor activity

Disease Progression

• Alzheimer's disease features:
• Gradual and progressive onset
• Initial mild symptoms such as forgetfulness worsen over years
• Severe cognitive impairment and dependency develops
• The disease course can extend for several years to a decade or more
• Delirium exhibits:
• Rapid onset, typically developing within hours or days
• Fluctuating severity throughout the day
• Quick resolution with treatment or underlying cause correction
• Persistence may occur if the trigger remains

Causative Agents

• Alzheimer's disease:
• Has no single causative agent
• Linked to amyloid-beta plaques and neurofibrillary tangles (tau protein aggregates)
• Mitochondrial dysfunction and chronic inflammation are also implicated
• Delirium is often triggered by reversible factors, including:
• Infections like pneumonia or urinary tract infections
• Metabolic disturbances
• Drug intoxication or withdrawal
• Post-surgical states

Contributing Factors

• Alzheimer's disease:
• Age
• Genetic predispositions like the APOE ε4 allele
• Cardiovascular risk factors like hypertension, high cholesterol, and diabetes
• Traumatic brain injury
• Estrogen deficiency in females
• Delirium:
• Older age
• Preexisting cognitive impairment
• Visual or hearing impairment
• Multiple medications
• Recent surgery
• Dehydration
• Infections

Pathophysiological Mechanisms

• Alzheimer's disease:
• Accumulation of amyloid-beta leads to plaque formation
• Tau protein hyperphosphorylation forms neurofibrillary tangles
• Chronic neuroinflammation causes synaptic loss and neuronal death
• Reduced cerebral blood flow and mitochondrial dysfunction worsen the damage
• Delirium:
• Disruption of neurotransmitter balance, especially acetylcholine deficiency and dopamine excess, contributes to altered cognition and attention
• Inflammation and metabolic disturbances can play a role, particularly when related to infections or other acute conditions

Key Differences

• Alzheimer's is progressive and irreversible.
• Delirium is acute and reversible when the underlying cause is managed.

Explore key distinctions between Alzheimer's disease and delirium, focusing on their clinical manifestations, disease progression, causative agents, and underlying pathophysiological mechanisms. Understand the differences in cognitive decline, behavioral symptoms, and the fluctuating nature of delirium compared to the progressive onset of Alzheimer's.