Alzheimer disease (AD) is a neurodegenerative disorder that is characterized by a slow and progressive loss of cognitive functions. In developed countries it is the most common form of late-onset dementia over 60 years old. The main pathological hallmarks of AD are extracellular amyloid plaques, intracellular neurofibrillary tangles,
and loss of neurons and synapses. These changes result in a cerebral atrophy with cognitive and neuropsychiatric symptoms. The vast majority of cases of Alzheimer's disease are late-onset cases over 60 years. However, there are early forms of AD (EOAD) in which the genetic load is high and associated with mutations in APP, PSEN1, and PSEN2 genes (encoding amyloid precursor protein, presenilin 1, and presenilin 2, respectively). These variants appear to be fully penetrant and result in Alzheimers disease with an early onset, in most cases before the age of 60 years. Alzheimerâs disease (AD) is the most common cause of senile dementia that progressively robs the victims of their memory, mental faculties and basic activities of independent living. Although specific genetic mutations have been identified that directly cause the disease, these cases are rare. Rather, interplay between genetic, metabolic and environmental factors seems to trigger the onset of pathological changes.
Last date updated on June, 2014