Beyond the Hypothesis of Serum Anticholinergic Activity in Alzheimer's Disease: Acetylcholine Neuronal Activity Modulates Brain-Derived Neurotrophic Factor Production and Inflammation in the Brain.

The brain of Alzheimer's disease (AD) patients is characterized by neurodegeneration, especially an acetylcholine (ACh) neuronal deficit with accumulation of ß-amyloid protein, which leads to oxygen stress and inflammation. The active oxygen directly damages the neuron by increasing intracellular Ca(2+). The inflammation is due to activation of the microglia, thereby producing cytokines which inhibit the production of brain-derived neurotrophic factor (BDNF). As the BDNF acts by neuronal protection, synaptogenesis and neurogenesis, the reduction of BDNF in the brain of AD patients worsens the symptoms of AD. On the other hand, treatment of AD patients with a cholinesterase inhibitor enhances ACh activity and inhibits inflammation. Then the expression of BDNF is restored and neuroprotection reestablished. However, there are several reports which showed controversial results concerning the relationship between BDNF and AD. We speculate that BDNF is related to some neurocognitive process and reflects neuronal activity in other neurodegenerative and neuropsychiatric disorders and that in the mild cognitive impairment stage, BDNF and choline acetyltransferase (ChAT) activities are hyperactivated because of a compensatory mechanism of AD pathology. In contrast, in the mild stage of AD, BDNF and ChAT activity are downregulated.

Plasma Cholinesterase Activity in Alzheimer's Disease.

Cholinesterase inhibitors (ChEIs) are not allowed to be prescribed in combination, which means that we need to select 1 of 3 ChEIs for use in a patient with Alzheimer's disease (AD). However, there is no quantitative analysis on the differences between these agents. In this article, we propose that plasma cholinesterase activity (pChE) could be used as the standard for differentiating between rivastigmine (Riv) and donepezil (Don) in the management of AD. To date, we have treated 6 patients with Riv 18 mg and 5 patients with Don 5 mg. The pChE is related to low-grade inflammation associated with AD, diabetes mellitus and lipid metabolic dysfunction. Moreover, low pChE is related to liver dysfunction. The pChE must be kept under control. We speculated that Riv is the most appropriate therapy for patients with relatively high pChE, whereas Don is best reserved for those AD patients with relatively low pChE.