Use of Sedative-Hypnotic Drugs and the Risk of Developing Alzheimer's Disease: A Systematic Review, Meta-Analysis and Meta-Regression.

Abstract

Background: Sedative-hypnotics, including benzodiazepines (BZDs) and non-benzodiazepine hypnotics (Z-drugs), are widely prescribed for insomnia and anxiety, particularly in older adults. Their long-term cognitive safety and potential association with Alzheimer's disease (AD) remain uncertain. We examined whether use of BZDs and Z-drugs is associated with incident AD and assessed variation by drug class, pharmacokinetics, and methodological factors.

Methods: PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched from inception to 16 August 2025 without language restrictions. Reference lists of eligible articles and reviews were screened. We included observational cohort and nested case-control studies enrolling adults without dementia at baseline that compared BZD or Z-drug users with non-users and reported incident AD diagnosed using validated clinical or administrative criteria (e.g., ICD-9/10, NINCDS-ADRDA, or NIA-AA). We excluded reviews, case reports, conference abstracts, studies with overlapping populations, and studies without extractable effect estimates. Two reviewers independently screened studies, extracted data, and assessed risk of bias using ROBINS-E. Random-effects meta-analyses were performed separately for odds ratios (ORs) and hazard ratios (HRs). Heterogeneity was quantified with I². Publication bias was evaluated with funnel plots and Egger test when applicable. Subgroup and meta-regression analyses assessed clinical and methodological modifiers. Certainty of evidence was rated using GRADE. The protocol was prospectively registered (PROSPERO CRD420251141623).

Results: Thirteen studies (N = 721,354 subjects) were included. Overall sedative-hypnotic use was associated with higher odds of AD (OR 1.29; 95% CI, 1.10-1.53; I² = 86.5%). Estimates restricted to HRs were attenuated and not statistically significant (HR 1.17; 95% CI, 0.87-1.58; I² = 73.1%). In subgroup analyses, BZDs overall (OR 1.21; 95% CI 1.07-1.36), Z-drugs (OR 1.14; 95% CI 1.10-1.18; I² = 0%), and short-acting agents (OR 1.19; 95% CI 1.04-1.36) were associated with higher odds of AD, whereas broad-acting BZDs were not (OR 1.01; 95% CI 0.98-1.05). Long-acting agents showed a borderline estimate (OR 1.44; 95% CI 0.99-2.09). Age-stratified analyses showed higher odds in individuals aged <75 years (OR 1.36; 95% CI 1.24-1.49), but not in those aged ≥75 years (OR 1.14; 95% CI 0.61-2.11). Estimates were also higher in studies using ICD-based definitions (OR 1.47; 95% CI 1.16-1.86) than in those using clinical criteria (OR 1.13; 95% CI 0.84-1.52). Meta-regression identified drug class and publication year as significant moderators. Risk of bias was rated moderate to serious in several studies, mainly due to residual confounding and exposure misclassification. Certainty of evidence ranged from very low to moderate.

Conclusions: Use of BZDs and Z-drugs was associated with increased odds of AD, with variation across drug classes and pharmacokinetic profiles. Short-acting agents, BZDs overall, and Z-drugs were associated with higher risk, whereas broad-acting BZDs were not; this finding should be interpreted with caution given subgroup heterogeneity and limited statistical power. Residual confounding and reverse causation limit causal inference. These results support careful prescribing and the need for prospective studies with detailed characterization of exposure, dose, duration, and clinical indication to clarify whether observed associations reflect drug-related effects or underlying disease processes.

Trial registration: PROSPERO protocol number: CRD420251141623.