Dementia is one of the most important health problems in the aging populations. The most frequent cause of it is Alzheimer’s disease (AD) which is characterized by intracellular neuro-fibrillary tangles (NFT) and the extracellular senile plaques.
The NFTs are mainly formed by the hyperphosphorylated microtubule-binding protein, the tau, while the senile plaques are composed of beta-amyloid protein cleaved from the amyloid precursor protein (APP) by the beta- and gamma-secretases. The pharmacotherapy of AD consists of symptomatic and disease-modifying therapies. The most frequently used therapeutic agents are the nootropic drugs supported by personal rather evidence based experiences.
The leading-edge therapy of AD at present is the inhibition of the acetylcholine-esterase enzyme (AChEI) with mainly cognitive symptomatic and weak disease-modifying effects; they are licensed in the mild and middle stages of AD (MMSE 26-10), but their effect is proved in the severe stage of the disease and they are effective in the management of the neuropsychiatric symptoms too. Memantine (which is an inhibitor of the N-metil-D-aspartate receptor) is used in the middle and severe stages of AD and it can be effectively combined with AChEIs. The future therapy of AD will possibly be a “causative” therapy. The most frequent directions are therapies aiming to decrease the production or the deposition of beta-amyloid peptide.
The active vaccination study of AN-1792 was terminated because of immunological side-effects, but several active and passive immunisation therapies are in development nowadays. It is also possible to inhibit the aggregation of the beta-amyloid peptide with peptide fragments or with Cu2+ and Zn2+ ion chelators. A promising direction is the inhibition of the enzymes responsible for the production of the beta-amyloid peptide: beta-secretase inhibitors with low molecular weight and penetrability through the blood-brain barrier are developed while the inhibitors of the gamma-secretase (some of them are the derivatives of the non-steroid anti-inflammatory drug ibuprofen) are tested in phase III trials.
The inhibition of NFT formation might be promising too and inhibitors of the enzymes responsible for the hyperphosphorylation of the tau (like the glycogen synthase kinase-3) are in develo ment. Several other therapeutic methods are studied.
NSAIDs and statins are useful in the prevention of the disease but they are failed in symptomatic treatment. There are promising studies in few patients using nerve growth factor therapy and some studies proved that peroxisome proliferator activated receptor (PPAR) agonist rosiglitazone (which is used to the treat diabetes mellitus) is effective in AD.
The presently modest therapeutic interventions of AD will explode in the near future and together with the improved diagnostics of the disease they will cause further specialization with increased treatment and caring costs amplified by the ever growing number of the patients. This means that AD is and will be one of the most important diseases for the health care systems.