The effect of inhaled aromatherapy on cognitive function in patients with cognitive impairment: A systematic review and meta-analysis

Background and purpose

Cognitive function is the basis of human thinking and behavior. Cognitive impairment has a serious impact on each individual and imposes a financial burden to families and healthcare systems. Inhalation aromatherapy has advantages, due to its safety, convenience, lack of toxicity, and wide use in the treatment of cognitive impairment. This systematic review was conducted to provide evidence for the use of inhaled aromatherapy in patients with cognitive impairment.

Methods

We searched nine databases for pertinent Chinese and English studies published through November 2024 studies using inhaled aromatherapy in patients with cognitive impairment. Literature screening and data extraction were performed independently by two researchers and evaluated using the Cochrane Collaboration's quality criteria and were then cross-checked. A meta-analysis was carried out using Cochrane's Review Manager (RevMan, version 5.4), and we followed the PRISMA guidelines.

Results

We included fourteen studies involving 888 patients with cognitive impairment in our study. Meta-analyses indicated that inhaled aromatherapy increased Mini-mental State Examination (MMSE, mean difference MD = 3.89 95 % CI [3.19, 4.58], P < 0.00001) and Montreal Cognitive Assessment Scale (MoCA, MD = 4.11, 95 % CI [3.54, 4.68], P < 0.00001) scores and decreased Homocysteine levels (Hcy, MD = −2.27 95 % CI [−2.80, −1.74], P < 0.00001) in patients with cognitive impairment compared with controls.

Conclusion

Inhaled aromatherapy could improve global cognition and lower Hcy in patients with cognitive impairment.