Trends in the prevalence of antipsychotic drug use among patients with Alzheimer's disease and other dementias including those treated with antidementia drugs in the community in the UK: a cohort study

OBJECTIVE: To investigate the pattern and trends of use of antipsychotics, antidepressants, hypnotics and anxiolytics in Alzheimer's disease and other dementias and in patients treated with antidementia medications. DESIGN: Cohort study with dementia patients formed in the UK Clinical Practice Research Datalink. Participants Patients with incident dementia, between 1995 and 2011 and a reference non-dementia cohort matched on age, gender and date of dementia diagnosis. Two subcohorts included new users of acetylcholinesterase inhibitors (AChEIs) and memantine. The study endpoint was use of antipsychotics, antidepressants, hypnotics and anxiolytics up to 10 years before and 4 years after dementia diagnosis, and for up to 5 years before and 1 year after first use of AChEI or memantine. RESULTS: 50 349 patients with incident dementia diagnosis and 50 349 matched controls, 10 794 first-time users of AChEI and 669 of memantine. The mean prevalence of antipsychotic use from 1995 to 2011 on diagnosis of dementia was 12.5%, decreasing from 19.9% in 1995 to 7.4% in 2011. There was an increase in antidepressant use (10.7–26.3%) and a small increase in anxiolytic use. The matched cohort showed a lower use of antipsychotics and anxiolytics but a rise in antidepressants (5.9–13.4%). Both groups showed a decrease in hypnotic use. 10.6% of AChEI and 26.3% of memantine users were prescribed antipsychotics, 34.1% and 26.3% antidepressants, 13.2% and 4.1% anxiolytics and 18.4% and 8.3% hypnotics. The slopes for monthly use of antipsychotics were positive in the year leading up to AChEI and memantine use; after treatment initiation the slope for AChEI users continued to increase but at a reduced rate whereas antipsychotic use declined for memantine users. CONCLUSIONS: The marked reduction in antipsychotic use in dementia is to be welcomed while there was a steady increase in antidepressant use. There was a decline in antipsychotic use after the initiation of memantine.