Mini Reviews in Medicinal Chemistry - Volume 2, Issue 1, 2002

The numerous advances in the understanding of the neurobiology of Alzheimer's disease in the past 15 years have suggested many new potential targets for therapeutic intervention. This article gives a broad overview of the spectrum of targets for AD treatment, with particular emphasis on amyloid β-peptides and tau protein.

The cholinergic hypothesis of Alzheimer's disease has spurred the development of numerous structural classes of compounds with different pharmacological profiles aimed at increasing central cholinergic neurotransmission, thus providing a symptomatic treatment for this disease. Indeed, the only drugs currently approved for the treatment of Alzheimer's disease are cholinomimetics with the pharmacological profile of acetylcholinesterase inhibitors. Recent evidence of a potential disease modifying role of acetylcholinesterase inhibitors and M1 muscarinic agonists have led to a revival of this approach, which might be considered as more than a symptomatic treatment.

A large amount of structural information on AChE and AChE-inhibitor complexes is currently available. Based on that, molecular modeling studies can be intensively used to gain insight into the mechanism of action of the enzyme and the molecular determinants that modulate the potency of inhibitors. In turn, this knowledge can be exploited to design new compounds leading to more effective cholinergic strategies. This manuscript reviews recent developments in the design of reversible acetylcholinesterase inhibitors.

Research on the molecular basis of Alzheimer's disease has elucidated pathogenic pathways from which a range of rational pharmacological interventions has emerged. The most promising strategies involve approaches to retarding, halting or preventing the formation or accumulation of beta amyloid plaques and neurofibrillary tangles. Other therapeutic approaches include those acting via excitatory amino acid receptors, limiting the oxidative stress and inflammatory response associated with dementia, molecules with nerve growth factor like activity. In the present article these and the other recent advances in the neurobiology and pharmacotherapy of AD will be reviewed.

The deposit of two proteins in the brain characterizes Alzheimer's disease: deposits of β-amyloid protein to form senile plaques and tau protein in neurofibrillary tangles. This review discusses transgenic animals overexpressing normal or mutated tau protein as well as kinases involved in tau hyperphosphorylation. These animals hold a great potential as tools to test the effects of forthcoming therapeutical agents for Alzheimer's disease.

Alzheimer's disease (AD) is a complex disorder associated with multiple genetic defects either mutational or of susceptibility. Information available on AD genetics does not explain in full the etiopathogenesis of AD, suggesting that environmental factors and / or epigenetic phenomena may also contribute to AD pathology and phenotypic expression of dementia. The genomics of AD is still in its infancy, but is helping to understand novel aspects of the disease including genetic epidemiology, multifactorial risk factors, pathogenic mechanisms associated with genetic networks and genetically-regulated metabolic cascades. AD genomics is also helping to develop new strategies in pharmacogenomic research and prevention. Functional genomics, proteomics, pharmacogenomics, high-throughput methods, combinatorial chemistry and modern bioinformatics will greatly contribute to accelerate drug development for AD and other complex disorders.Main genes involved in AD include mutational loci (APP, PS1, PS2, TAU) and multiple susceptibility loci (APOE, A2M, AACT, LRP1, IL1A, TNF, ACE, BACE, BCHE, CST3, MTHFR, GSK3B, NOS) distributed across the human genome. Genomic associations integrate bigenic, trigenic, tetragenic or polygenic matrix models to investigate the genomic organization of AD in comparison to the control population. Similar genetic models are used in pharmacogenomics to elucidate genotype-specific responses of AD patients to a particular drug or combination of drugs. Using APOE-related monogenic models it has been demonstrated that the therapeutic response to drugs in AD is genotype-specific. A multifactorial therapy combining 3 different drugs yielded positive results during the 6-12 months in approximately 60 percent of the patients. With this therapeutic strategy, APOE-4 / 4 carriers were the worst responders, and patients with the APOE-3 / 4 genotype were the best responders. In bigenic and trigenic models it was possible to differentiate the influencial effect of PS1 and PS2 polymorphic variants on mental performance in response to multifactorial therapy. The application of functional genomics to AD can be a suitable strategy for harmonization in molecular diagnosis and drug clinical trials. Furthermore, the pharmacogenomics of AD may contribute in the future to optimise drug development and therapeutics, increasing efficacy and safety, and reducing side-effects and unnecessary costs.

Active and passive immunization against fibrillar β-amyloid of various mice models of Alzheimer's disease leads to the disaggregation and inhibition of plaque formation. Preliminary results showing improved behaviour and memory function obtained after administration of anti-β-amyloid vaccines to transgenic mice encourage these and related approaches for testing in the treatment and prevention of Alzheimer's disease.