The efficacy of cholinesterase inhibitors in treating the behavioural symptoms of dementia.

Multiple behavioural and psychological symptoms of dementia (BPSD) are commonly associated with all dementia subtypes, and worsen during disease progression. BPSD arise due to impairment of cholinergic function in the cortex, hippocampus and related limbic systems. Recent studies have investigated the effect of cholinesterase inhibitors on BPSD. The dual acetylcholinesterase/butyrylcholinesterase (AChE/BuChE) inhibitor rivastigmine was shown to have several potential advantages over the AChE-selective inhibitors donepezil and galantamine for the treatment of BPSD. Rivastigmine appears to be effective across the range of dementia severity from mild to severe, and across the spectrum of dementia (Alzheimer's disease [AD], the AD variant with Lewy bodies, Parkinson's disease dementia and vascular dementia subtypes). It also appears to have a disease-modifying potential. Rivastigmine improved a wider range of behavioural symptoms (apathy, anxiety/depression, hallucinations and delusions) than donepezil and galantamine (which improved apathy and depression/anxiety only). Unlike donepezil, rivastigmine reduced the need for psychotropic medications to treat BPSD. Dual inhibition of AChE and BuChE and brain-region selectivity through preferential inhibition of the G1 isoform of AChE may provide the underlying reasons for the apparently greater and broader efficacy of rivastigmine over AChE-selective inhibitors for the treatment of BPSD. However, randomised, controlled trials are required to compare dual inhibitors, such as rivastigmine, and AChE-selective agents, to confirm and quantify any differences in their effects on BPSD.