Current therapies in dementia

Currently, cholinergic therapies for Alzheimer's disease (AD) have been developed and widely accepted based upon an observation that presynaptic cholinergic neurons in the basal nucleus of Meynert that widely project to the cerebral cortices are consistently damaged in AD brains. Since it is likely that the loss of central cholinergic activity may be associated with cognitive worsening in patients with AD, it is hypothesized that cholinergic augmentation could improve the cognitive ability of patients with AD. Cholinesterase inhibitors represent one way of implementing this strategy by inhibiting the breakdown of acetylcholine and increasing its availability in synapses. Indeed, several recent clinical trials of donepezil, galanthamine and rivastigmine have come to the conclusion that these cholinesterase inhibitors have overall beneficial effects in cognitive as well as global functions. American Academy of Neurology recommended a use of cholinesterase inhibitors as a first choice medicine in the treatment of AD. All 3 major studies of Donepezil from USA, Europe and Japan have reached the same conclusion favoring Donepezil in the treatment of mild to moderate AD. Donepezil can also be used as a safe and efficacious drug in the elderly aged 85 or older. Clinical trial of galantamine is in progress in Japan. Moreover, herbal medicines named kami-untan-to and hachimi-jiou-gan have been shown to be beneficial in some priority studies with a small sample size. It is critically needed to widen therapeutic windows in the treatment of AD.