Early-onset Alzheimer's disease, also called early-onset Alzheimer's disease or early-onset AD, is the term used for cases of Alzheimer's disease diagnosed before the age of 65. It is an uncommon type of Alzheimer's disease, accounting for 5-10% of all cases of Alzheimer's disease. About 13% of cases of early-onset Alzheimer's disease are familial Alzheimer's disease, where a genetic predisposition leads to the disease. Other forms of Alzheimer's disease share the same characteristics as late-onset Alzheimer's disease. Little is understood about how the disease begins. Nonfamilial early-onset Alzheimer's disease can develop in people in their 30s or 40s, but it is very rare. Most people with early-onset Alzheimer's are in their 50s or early 60s. History of Alzheimer's disease: The symptoms of Alzheimer's disease are distinct in the nosology of the disease as they were first identified by Emil Kraepelin, and the symptoms of neurological diseases were observed by Alois Alzheimer in 1906. In this sense, the disease was discovered by Emil Kraepelin and Alois Alzheimer, who worked in Emil Kraepelin's laboratory. Because of the importance of Kraepelin's disease to the basics of neurological diseases, Emil Kraepelin decided that the disease would be called Alzheimer's disease. Familial Alzheimer's disease: Familial Alzheimer's disease, or early-onset familial Alzheimer's disease, is an uncommon form of Alzheimer's disease that usually occurs in early life, defined by age 65 and is inherited by genetic factors, and is defined by genes, and other characteristics such as the age at which the disease appears. It accounts for approximately half of cases of early-onset Alzheimer's disease. Requires Familial Alzheimer's disease is a disease in which at least one person has a first-degree relative with Alzheimer's disease. Non-familial Alzheimer's disease is referred to as "sporadic Alzheimer's disease", where the risk factors in the genes are small and not varied. In the case of early familial Alzheimer's disease, estimates indicate only 0.035 of all Alzheimer's diseases. It has provided a useful model for studying various aspects of the disease. Currently: The mutations of the familial early Alzheimer's disease gene have led the vast majority of animal models to the discovery and development of therapeutics in Alzheimer's disease. Clinical symptoms Alzheimer's disease is the most common cause of dementia and often appears late in life. It is an inevitable fate, generally within ten years of the first signs. An early sign of Alzheimer's disease is unusual memory loss. Especially when remembering new events and the names of people and things, logopenic primary progressive aphasia. As the disease progresses, the patient develops serious problems, accompanied by mood swings and an inability to perform complex activities such as driving a car. In the later stages, the patient loses the ability to remember how to do simple things such as combing his hair and will then need constant care. Anatomically, diseases Familial Alzheimer's disease is virtually indistinguishable from other forms of the disease. Amyloid deposits can be seen in parts of the brain tissue. This amyloid protein forms plaques and neurofibrillary tangles that progress through the brain. The plaques are very rare and are unique to Alzheimer's disease; this may occur when there are mutations in the gene that produces a functional but defective protein, rather than the products of a nonfunctional gene that are usually the result of mutations. The underlying neurobiology of the disease has only recently been understood. Researchers have mapped the inflammatory pathways involved in the development and progression of the relapsing features of Alzheimer's disease. Key molecules involved in these pathways include microglial cells, amyloid beta, and proinflammatory aggregates. Amyloid beta is a small fragment of a larger protein called amyloid leader protein. When amyloid leader protein reacts, it is broken down into other protein fragments. One of the fragments produced in this process is β-amyloid. β-amyloid is more sticky than any other fragment produced from the amyloid precursor protein and because of this property it begins to accumulate in the brain. The accumulation is caused by genetic variations and abnormalities in neurobiology. Finally, the fragments form small units. Then fibers, beta-amyloid fragments, and finally plaques. The presence of β-amyloid plaques in the brain prompts the body to recruit and activate astrocytes. This is normally a beneficial response. However, not with Alzheimer’s because beta-amyloid plaques stimulate glial cells to release oxygen free radicals. Free radicals are normally effective against abnormal cells. But free radicals cannot distinguish between normal and abnormal cells. Free radicals destroy beta-amyloid plaques but also destroy surrounding healthy tissue. As more tissue dies, glial cells release chemokines and stoichioids. These aggregates recruit more glial cells which means more free radicals. This uncontrolled response and inflammatory response contribute to the neurodegenerative development of Alzheimer's disease. Genetics Familial Alzheimer's disease is caused by mutations in at least one of three genes: presenilin 1, presenilin 2, and amyloid precursor proteins. Mutations in other genes in the study. Presenilin 1 The presenilin 1 gene was identified by Sherrington in 1995 and several mutations have been identified. Mutations in this gene definitely cause familial Alzheimer's disease type 3, usually in people under 50 years of age. This protein has been identified as part of an enzyme complex that cleaves beta-amyloid from APP. The gene contains 14 exons and the estimated coding area is 60 kb, as reported by Rogev M. 1997 and Del Vivero 1999. The protein that the gene encodes is an integral membrane protein. As mentioned by Koichi 2002, Notch1 ps1 is thought to have a role in somitogenesis in the embryo. It also acts on amyloid precursor protein, which gives a possible role in the pathogenesis of FAD. Homologs of PS1 have been found in plants, invertebrates, and other vertebrates. Some of the mutations in the genes, of which there are more than 90, include: His163Arg, Ala246Glu, Leu286Val, and Cys410Tyr. The most common mutation is Glu318Gly and this predisposes individuals to familial Alzheimer's disease, with a study by Tadi finding an incidence of 8.7% in patients with familial presenilin 2: The presenilin 2 gene is very similar in structure and function to presenilin 1. Located on the chromosome, mutations in this gene cause flavin adenine dinucleotide type IV. This gene was discovered by Rudolf Tanzi and Jerry Schellenberg in 1995. A subsequent study by Kovacs in 1996 showed that presenilin 1 and 2 proteins were expressed in similar amounts, and in similar organelles, in mammalian neurons. Levi-Lahd reported that presenilin 2 contained 12 exons, 10 of which were coding exons, and that the original basal transcript encoded a 448 amino acid peptide, with 67% homology. For presenilin 1, this protein is known to be part of the plaque enzyme complex that degrades amyloid beta peptide. Mutations of APP have not been studied as much as for presenilin 1, but distinct allelic variants have been known. These include Asn141Ile, which was first identified by Rudolf Tanzi and Jerry Schellingberg in families in Wolga, Germany, with early familial Alzheimer's disease. One of these studies of Nucleol found amyloid angiogenesis in affected individuals in the family. This phenotype may be explained by Tomita's study, suggesting that Asn141Ile mutations alter amyloid beta-peptide metabolism, causing increased deposition of the protein in plaques. Other allelic variants are Met239Val, which was identified by the Italian Rogge, who also suggested earlier that this gene might be homologous to presenilin 1, and Asp439Ala mutations in exon 12 of the gene, which were suggested by Liu to alter the endoproteolytic activity of presenilin 2. Amyloid beta-peptide Amyloid beta-peptide mutations are located on the long arm of chromosome 21, which causes Alzheimer's disease. Familial. PathophysiologyFollowing β-secretase cleavage, amyloid beta peptide is cleaved by a membrane-bound protein complex called γ-secretase to generate amyloid beta. Presenilin 1,2 are the intermediate enzymes in the complex with nicastrin, IPH1 and presenilin 1. Cleavage of alpha-secretase from amyloid beta peptide, which prevents amyloid beta production, is the most common event in amyloid beta peptide processing. Twenty-one allelic mutations have been identified in the amyloid beta gene. These ensure early-onset Alzheimer's disease, all of which occur in a region within amyloid beta peptide that encodes the amyloid beta domain. Genetic testingGenetic testing is available for individuals and relatives with symptoms. Early-onset Alzheimer's disease has devastating effects on the careers, caregivers, and family members of the affected individual. Many affected individuals are within the age range of caregivers of children. Children of people with pre-puberty suffer physically and emotionally and their parents are unable to care for them. Those who work lose their ability to do their jobs and are forced into early retirement, and when it is predictable the employee should discuss their future with their employers regarding the loss of skills. Those forced into early retirement may not have access to the full range of benefits available to those who retire at the minimum age set by the government. With some jobs, a mistake can have serious consequences for a large number of people, and cases of distress have been reported in people with early-onset Alzheimer's. People with Alzheimer's lose the ability to meet their own needs, such as managing money.