Cognitive effects of individual anticholinergic drugs: a systematic review and meta-analysis.

UNLABELLED

Anticholinergics (ACs) are among the most prescribed drugs. Investigating the impaired cognitive domains due to individual ACs usage is associated with controversial findings.

OBJECTIVE

The objective of this study was to investigate the effects of individual ACs on different aspects of cognitive function based on clinical trial studies.

METHODS

This systematic review was conducted following the PRISMA statement. A systematic search was performed in Embase, PubMed, Cochrane Library, Scopus, and Web of Science databases. Risk of bias (RoB) was assessed by the Joanna Briggs Institute checklists and the meta-analysis was performed using the CMA software.

RESULTS

Out of 3,026 results of searching, 138 studies were included. A total of 38 studies that assess the cognitive impacts of scopolamine were included in the meta-analysis. Included studies reported cognitive effects of scopolamine, mecamylamine, atropine, biperiden, oxybutynin, trihexyphenidyl, benzhexol, and dicyclomine; however, glycopyrrolate, trospium, tolterodine, darifenacin, fesoterodine, tiotropium, and ipratropium were not associated with cognitive decline. Based on the meta-analyses, scopolamine was associated with reduced recognition (SDM -1.84; 95%CI -2.48 to -1.21; p<0.01), immediate recall (SDM -1.82; 95%CI -2.35 to -1.30; p<0.01), matching to sample (SDM -1.76; 95%CI -2.57 to -0.96; p<0.01), delayed recall (SDM -1.54; 95%CI -1.97 to -1.10; p<0.01), complex memory tasks (SDM -1.31; 95%CI -1.78 to -0.84; p<0.01), free recall (SDM -1.18; 95%CI -1.63 to -0.73; p<0.01), cognitive function (SDM -0.95; 95%CI -1.46 to -0.44; p<0.01), attention (SDM -0.85; 95%CI -1.38 to -0.33; p<0.01), and digit span (SDM -0.65; 95%CI -1.21 to -0.10; p=0.02). There was a high RoB in our included study, especially in terms of dealing with possible cofounders.

CONCLUSION

The limitations of this study suggest a need for more well-designed studies with a longer duration of follow-up on this topic to reach more reliable evidence.