Can Alzheimer's disease cause convulsions or syncope in older adults with a history of cognitive decline and dementia?

Can Alzheimer's Disease Cause Convulsions or Syncope?

Alzheimer's disease itself does not directly cause syncope, but patients with Alzheimer's are at significantly increased risk for syncope due to multiple cardiovascular and autonomic factors, while advanced Alzheimer's disease is an established independent risk factor for new-onset seizures (convulsions).

Syncope in Alzheimer's Disease

Alzheimer's Does Not Directly Cause Syncope

The relationship between Alzheimer's disease and syncope is indirect—cognitive impairment complicates the clinical presentation and diagnosis of syncope rather than causing it 1. Cognitive impairment influences the accuracy of recall of syncopal events, and amnesia for loss of consciousness is common in older adults with dementia 1. Up to one-third of syncopal events in patients with dementia present as unexplained falls rather than classic syncope 1.

Multiple Cardiovascular Causes Are Common

In patients with Alzheimer's disease who experience syncope, comprehensive cardiovascular evaluation identifies a probable cause in approximately 69% of cases 2. The predominant etiologies include:

• Carotid sinus syndrome (cardioinhibitory response) 2
• Cardiac conduction abnormalities including complete atrioventricular block and sinus node dysfunction 2
• Severe orthostatic hypotension 2
• Cardiac arrhythmias such as paroxysmal atrial fibrillation 2

Patients with dementia typically have a median of five risk factors for syncope or falls, making risk-factor stratification complex 1. The boundaries between falls and syncope are poorly delineated in this population 1.

Medication-Related Considerations

Cholinesterase inhibitors (donepezil, rivastigmine, galantamine) used to treat Alzheimer's disease can cause bradycardia and related adverse effects including falls and syncope 1. However, when syncope occurs in patients taking these medications, noninvasive cardiovascular evaluation should be performed before discontinuing the cholinesterase inhibitor, as underlying cardiovascular abnormalities are frequently identified 2.

Clinical Approach to Syncope in Alzheimer's Patients

The diagnostic evaluation should include 1:

• Morning orthostatic blood pressure measurements (supine and standing)
• Supine and upright carotid sinus massage (integral to initial evaluation unless contraindicated)
• Detailed witness account of episodes (though unavailable in 40-60% of cases)
• Assessment of medications including polypharmacy, drug-drug interactions, and medications that lower blood pressure
• Evaluation for dehydration, infection, or fever as precipitating factors

A comprehensive multidisciplinary approach is reasonable for older adults with dementia and syncope, incorporating assessment of frailty, comorbidities, cognitive function, and medications 1.

Convulsions (Seizures) in Alzheimer's Disease

Advanced Alzheimer's Is an Independent Risk Factor for Seizures

Advanced Alzheimer's disease alone is an important independent risk factor for new-onset generalized tonic-clonic seizures in older adults 3. In a prospective 90-month study, no healthy control subjects developed seizures, while 16% (7 of 44) of patients with mild Alzheimer's disease developed at least one documented seizure 3.

Key Characteristics of Alzheimer's-Related Seizures

• Seizures occur exclusively in advanced/severe stage dementia, not in mild-to-moderate disease 3
• Seizures are generalized tonic-clonic in type 3
• No other epileptogenic factors are identified clinically or neuropathologically 3
• Seizures represent a late complication of the neurodegenerative process 3

Clinical Implications

The development of new-onset seizures in a patient with Alzheimer's disease should prompt evaluation for other potential epileptogenic causes, but clinicians should recognize that advanced Alzheimer's pathology itself is sufficient to cause seizures 3. The widespread neuronal damage and pathological accumulation of amyloid-beta plaques and neurofibrillary tangles in advanced disease likely contribute to seizure susceptibility 4.

Common Pitfalls to Avoid

• Do not assume syncope is benign in patients with Alzheimer's disease—comprehensive cardiovascular evaluation identifies treatable causes in the majority of cases 2
• Do not automatically discontinue cholinesterase inhibitors when syncope occurs—perform cardiovascular evaluation first, as underlying cardiac abnormalities are usually responsible 2
• Do not overlook syncope as a cause of falls—approximately 30% of older adults with dementia who present with nonaccidental falls may have had syncope 1
• Do not attribute new-onset seizures to "normal aging"—seizures in advanced Alzheimer's represent a specific disease complication requiring appropriate evaluation and management 3