All three cholinesterase inhibitors and memantine are currently the only effective licenced treatments for dementia,3 but their clinical effect can be small and there is no convincing evidence that they modify the disease process in AD.4 Also, it is unclear whether galantamine, rivastigmine or donepezil should be used by patients with severe AD, or whether memantine is the optimal treatment for severe AD.5 Here, BCHE is linked to Alzheimer disease.