Dementia is a chronic or progressive syndrome, characterized by impaired cognitive capacity beyond what could be considered a consequence of normal aging. It affects the memory, thinking process, orientation, comprehension, calculation, learning ability, language, and judgment; although awareness is usually unaffected. Alzheimer's disease (AD) is the most common form of dementia; symptoms include memory loss, difficulty solving problems, disorientation in time and space, among others. The disease was first described in 1906 at a conference in Tubingen, Germany by Alois Alzheimer. One hundred and ten years since its first documentation, many aspects of the pathophysiology of AD have been discovered and understood, however gaps of knowledge continue to exist. This literature review summarizes the main underlying neurobiological mechanisms in AD, including the theory with emphasis on amyloid peptide, cholinergic hypothesis, glutamatergic neurotransmission, the role of tau protein, and the involvement of oxidative stress and calcium.

Wilson's disease is an inherited disorder in which defective biliary excretion of copper leads to its accumulation, particularly in the liver and brain. Mutations in the ATP7B gene on chromosome 13 cause Wilson's disease. If left untreated it will cause liver failure, neurological damage, and will be life threatening. It is considered a rare disease afflicting approximately 1 in 30,000 persons worldwide, although this rate is similar in the different countries some places show higher incidence rates. Since Costa Rica reports the highest number of cases per population, essential public health initiatives that promote wellbeing, prevent disease complications, and prolong life among the affected population have been carried out during the last decades. The most recent lead in this matter is the conformation of the Costa Rica's National Alliance for Wilson's disease whose main objective is to provide practical, operational, timely and relevant guidance to patients, families, and healthcare professionals in the region for early diagnosis and treatment. The development and implementation of the National Alliance for Wilson's disease activities is crucial because it will reaffirm that early intervention and appropriate treatment, will reduce if not eliminate the burden of Wilson's disease.

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