Can benztropine decrease cognition?

Yes, benztropine can significantly decrease cognition and should be avoided or discontinued when possible, particularly in older adults.

Benztropine impairs memory, attention, and concentration through its strong anticholinergic effects, and this cognitive burden increases with dose. 1

Mechanism and Evidence of Cognitive Impairment

Benztropine possesses potent anticholinergic properties that block muscarinic receptors throughout the central nervous system 2. This anticholinergic activity directly interferes with acetylcholine transmission, which is critical for memory formation and cognitive processing. The FDA label explicitly warns that "mental confusion and excitement may occur with large doses, or in susceptible patients" and notes that "visual hallucinations have been reported occasionally" 2.

Research Demonstrating Cognitive Decline

Multiple controlled studies confirm benztropine's negative cognitive effects:

• Dose-dependent memory impairment: A controlled study using benztropine versus glycopyrrolate (a peripheral anticholinergic) showed that benztropine significantly worsened free recall performance, with memory impairment continuing to increase as doses approached the upper clinical range 3.

• Specific cognitive domains affected: A head-to-head comparison with amantadine demonstrated that benztropine 4 mg/day impaired free recall and time perception, with subjects reporting significantly greater perceived memory impairment. The drug specifically impairs storage of new information into long-term memory while having less effect on retrieval or immediate memory 4.

• Improvement upon discontinuation: When benztropine was withdrawn in chronic schizophrenic patients, Wechsler Memory Scale scores reliably increased, with particular improvements in attention and concentration 5. A more recent 12-week discontinuation study showed significant improvements in cognitive composite scores at weeks 6,8, and 12, particularly on motor and symbol-coding tasks 6.

• Independent association with reduced cognition: In a large study of 567 bipolar disorder patients using machine-learning analysis, benztropine was independently associated with significantly reduced cognitive scores compared to those not receiving it, showing a significant dose-related relationship across all cognitive measures 7.

Clinical Guidelines: High-Risk Medication to Deprescribe

The 2019 AGS Beers Criteria and 2021 Mayo Clinic guidelines both classify anticholinergic medications like benztropine as high-risk drugs that adversely affect cognition in older adults 8, 1. The guidelines emphasize that:

• Anticholinergic medications cause "broad muscarinic receptor blockade resulting in negative effects on vision, urination, constipation, and cognition" 1
• Multiple anticholinergic drugs create an "anticholinergic burden" that adversely affects cognition, functional status, and activities of daily living scores 1
• These medications are associated with falls, confusion, delirium, emergency department visits, and hospitalizations 1

Clinical Recommendations

Discontinue benztropine when possible, particularly in:

• Older adults (any age, but especially >65 years)
• Patients with existing cognitive impairment or dementia
• Those taking multiple anticholinergic medications (high anticholinergic burden)
• Patients no longer experiencing extrapyramidal symptoms

If benztropine must be used:

• Limit duration to ≤7 days for prophylaxis of acute dystonia (the period of highest risk) 9
• Use the lowest effective dose, as cognitive impairment is dose-dependent 7, 3
• Monitor closely for confusion, memory problems, and functional decline 2
• Avoid in patients with mental disorders, as it can intensify psychiatric symptoms 2

Common Pitfalls to Avoid

1. Continuing benztropine indefinitely: Many clinicians prescribe benztropine prophylactically but fail to discontinue it after the acute dystonia risk period (first 7 days) 9

2. Overlooking cognitive side effects: The FDA warns that benztropine may impair mental abilities required for hazardous tasks like driving 2, yet these effects are often underrecognized clinically

3. Using in older adults without strong indication: Only 14.2% of patients withdrawn from benztropine developed extrapyramidal symptoms severe enough to require resumption 5, suggesting many patients receive it unnecessarily

4. Ignoring cumulative anticholinergic burden: Benztropine's effects compound when combined with other anticholinergic medications (antihistamines, bladder agents, muscle relaxants) 1

The evidence consistently demonstrates that benztropine causes clinically meaningful cognitive impairment that improves upon discontinuation, making it a medication that should be actively deprescribed whenever clinically feasible.