Alzheimer’s disease (AD) is a neurodegenerative disease with an aetiology that has not been fully elucidated. The pathologically is characterised by the presence of neurofibrillary tangles, senile plaques, deposition of amyloid beta peptide (Aβ) and a selective loss of neurones replaced by decreased synaptic density. This histopathological condition has several possible causes, including genetic defects, apoptosis, excitotoxicity, inflammatory mechanisms, altered zinc distribution in AD brain or effects linked to the female hormone oestrogen. Lately, oxidative stress has received increasing interest as a possible cause of the neurodegeneration. All these topics are discussed in this review, together with altered signal transductions that are found in the Alzheimer-affected brain. Special attention is also given to the role of the glutamatergic system.