Impact of antidementia medicines on the dispensing of antidepressants, anxiolytics and antipsychotics

Behavioural and psychological disturbances are common among individuals with dementia. It is unclear if the use of antidementia medicines reduces their presence. This study aimed to clarify if the introduction of antidementia medicines leads to a decline in the dispensing of antidepressants, anxiolytics and antipsychotics. We used time-series analyses to examine the association between the supply of cholinesterase inhibitors or memantine and psychotropics. Participants were males and females aged 60 years or over included in the Australian 10 % Pharmaceutical Benefits Scheme database between 2013 and 2024. The outcomes of interest were the dispensing of antidepressants, anxiolytics and antipsychotics, and the exposure the dispensing of antidementia medicines. The panel dataset included 466,210 individuals. The odds ratio of being dispensed a psychotropic in association with the supply of an antidementia medicine was 8.40 (95 %CI=8.05-8.78) for antidepressants, 1.99 (95 %CI=1.89-2.09) for anxiolytics, and 24.31 (22.54-26.22) for antipsychotics. Interrupted time-series analyses showed that the introduction of an antidementia medicine decreased the annual rate of dispensing of antidepressants (-0.7 % per year), but increased the dispensing of anxiolytics by 0.8 % per year and antipsychotics by 1.0 % per year. Contrary to our hypothesis, interrupted time series analyses showed that the supply of antidementia medicines was associated with subsequent increased rate of dispensing of psychotropic agents, particularly anxiolytics and antipsychotics. Antidementia medicines are not effective at reducing the clinical use of anxiolytics and antipsychotics.