Can meclizine increase the risk of dementia?

Meclizine and Risk of Dementia

Meclizine may increase the risk of dementia due to its anticholinergic properties, which should be avoided in elderly patients and those with cognitive impairment. 1

Anticholinergic Medications and Cognitive Risk

Meclizine (commonly used for vertigo, motion sickness, and dizziness) belongs to the class of first-generation antihistamines with significant anticholinergic properties. According to current guidelines:

• Medications with anticholinergic properties should be minimized in patients with dementia to prevent cognitive impairment 1
• Regular review of medications is necessary to minimize polypharmacy and reduce the risk of cognitive impairment, as concurrent use of multiple medications with cognitive side effects is associated with measurable cognitive decline 1
• Elderly patients and those with dementia may have increased sensitivity to cognitive side effects of medications 1

Mechanism of Risk

The anticholinergic activity of meclizine works by blocking acetylcholine, a neurotransmitter critical for memory and cognitive function. This mechanism:

1. Interferes with cholinergic neurotransmission in the brain
2. Reduces acetylcholine levels, which are already depleted in dementia
3. May contribute to cognitive decline, particularly when used long-term

Risk Factors That Increase Concern

The risk of cognitive impairment from meclizine appears to be higher in:

• Elderly patients (over 65 years)
• Patients with existing mild cognitive impairment
• Those taking multiple medications with anticholinergic properties
• Long-term users of the medication

Evidence from Related Medications

While specific studies on meclizine and dementia risk are limited, evidence from similar anticholinergic medications suggests:

• Medications with opposing mechanisms to cholinesterase inhibitors (like anticholinergics) should be avoided to preserve cognitive abilities in elderly patients with existing mild dementia 1
• Benzodiazepines and other medications with anticholinergic properties have been associated with increased dementia risk 2, 3
• The association between anticholinergic medications and dementia appears stronger with cumulative dose and treatment duration 2

Recommendations for Clinical Practice

1. Avoid meclizine in patients with dementia or at high risk for cognitive decline
2. Consider alternative treatments with less anticholinergic burden:
   • For vertigo/dizziness: vestibular rehabilitation exercises
   • For motion sickness: non-anticholinergic alternatives when necessary
3. If meclizine must be used:
   • Use the lowest effective dose
   • Limit duration of treatment
   • Regularly assess continued need and cognitive function
   • Avoid combining with other anticholinergic medications

Monitoring and Management

• Perform brief assessment of cognitive function before starting meclizine and periodically during treatment 1
• Conduct regular medication reviews to identify and minimize anticholinergic burden
• Consider deprescribing meclizine in elderly patients, especially those showing signs of cognitive decline

Caveat

The relationship between anticholinergic medications and dementia may involve some degree of reverse causation, as early undiagnosed dementia might lead to symptoms (like dizziness) that prompt the use of medications like meclizine 4. However, the prudent approach is to minimize anticholinergic exposure, particularly in vulnerable populations.