The impact of genetic variability on Alzheimer's therapies: obstacles for pharmacogenetic progress

Genetic load influences the therapeutic response to conventional drugs in Alzheimer's disease (AD). Pharmacogenetics (PGx) is the best option to reduce drug-drug interactions and adverse drug reactions in patients undergoing polypharmacy regimens. However, there are important limitations that make it difficult to incorporate pharmacogenetics into routine clinical practice.

This article analyzes the pharmacogenetic apparatus made up of pathogenic, mechanistic, metabolic, transporter, and pleiotropic genes responsible for the efficacy and safety of pharmacological treatment, the impact of genetic load on the outcome of multifactorial treatments, and practical aspects for the effective use of PGx.

Over 120 genes are closely associated with AD. There is an accumulation of cerebrovascular (CVn) and neurodegenerative (ADn) genes in AD. APOE-4 carriers accumulate more deleterious genetic load related to other CVn and ADn genes, develop the disease earlier, and are at a biological disadvantage compared to APOE-4 non-carriers. CYP2D6-PMs and APOE-4 carriers are the worst responders to anti-dementia drugs. Some limitations hinder the implementation of PGx in clinical practice, including lack of pharmacogenetic information for many drugs, low number of genes in PGx screening protocols, and educational deficiencies in the medical community regarding PGx and genomic medicine.