Alzheimer's disease, inflammation and non-steroidal anti-inflammatory drugs

Alzheimer's disease (AD) is a degenerative disease of the brain, which causes dementia. The disease is characterised by three main pathogenic factors: senile plaques, neurofibrillary tangles and inflammation. the participation of the local inflammatory reaction is confirmed especially by the results of studies dealing with activated microglia, reactive astrocytes, complement system, cytokines, reactive mediators of oxygen and nitrogen (free radicals), all of which participate significantly in inflammatory processes. These inflammatory markers are locally produced by brain cells, and occur in close proximity of beta-amyloid and tau protein deposits. Moreover, some epidemiologic and pilot clinical studies have proven that long-term administration of anti-inflammatory drugs have a protective effect on the onset of AD. Out of them, non-steroidal anti-inflammatory drugs (NSAIDs) are most extensively investigated medicaments. Despite some contradictory findings, the prevalent majority of these studies prove that long-term application of anti-inflammatory treatment can delay the onset, or at least slow down the progression of AD, namely in people between 65 and 75 years of age. The most appropriate prophylactic effect seems to be achieved by specific inhibitors of cyclooxygenase-2 (COX-2), namely celecoxib and rofecoxib. These preparations protect the gastrointestinal tract better than classical NSAIDs which inhibit both isoenzymes--COX-1 and COX-2. COX-2 is expressed in higher concentrations in the degenerating cells of the brain and this excessive expression can be decreased by selective inhibitors. The latter decrease also the excessive activation of some transcription factors (PPARgama and the nuclear factor kapa-B), which are responsible for the initiation of transcription of a number of pro-inflammatory genes. The selective inhibitors COX-2 can thereby have an anti-inflammatory effect operating on several levels. (Tab. 1, Fig. 1, Ref. 75.)