Evident before the onset of Alzheimer's dementia, occurs a slow deterioration of brain function, especially memory. Mild cognitive impairment (mild cognitive impairment in English) is the best known pre-dementia disorders. Its existence has been questioned especially by Professor Bruno Dubois, a specialist in Alzheimer's disease, while an article published in July 2007 (Lancet Neurology).
With the International Working Group for New Research Criteria for the Diagnosis of Alzheimer's Disease, the same author confirmed in November 2010 (The Lancet Neurology) The term mild cognitive impairment should disappear in favor of the diagnosis of "Alzheimer beginner or early stage, "according to new diagnostic criteria.
Risks and challenges pre-Alzheimer disorders
The diagnosis of Alzheimer's disease is made on average after 2.5 to 3 years of evolution and even later manifest in patients less than 65 years, according to the collective expertise of INSERM (2007). Hence the importance of early detection of Alzheimer's disease for early care and well organized. The first signs of cognitive decline appear very early in the disease (some 10 to 12 years before), because brain lesions do not affect the behavior of patients when the compensation phenomena are overwhelmed.
Alzheimer's disease currently affects 850,000 and a forecast of 1.2 million people in 2020 (IFRAD Foundation for Research on Alzheimer's Disease, 2011). Nearly half of patients are at a stage of severity moderately severe to severe, or more than 400,000 people (estimate based on group data and study EURODEM PAQUID
Foundation IFRAD, Professor Bruno Dubois).
It is estimated that nearly 20,000 the number of "young" patients with early-onset form, the greatest risk is being unfairly treated for a psychiatric illness then it is a neurological disease.
Causes of pre-Alzheimer disorders
In a world first article showing how early brain damage (Amieva et al. Annals of Neurology, November 2010), the team of Prof. Jean-François Dartigues certify that the cohort of 3 cities early signs of deterioration Intellectual appear 10 to 12 years before diagnosis of Alzheimer obvious.
For Professor Dartigues this insidious deterioration is the lack of compensation brain aging. A closer examination, normal aging and dementia Alzheimer carry the same mechanisms, but in the second case, they are more serious and unevenly distributed in the brain. As if the metabolic derailed, under the combined effect of a real aggravation and lack of usual correction.
Neurons in the medial temporal region of the brain called the hippocampus deteriorates first. The hippocampus is where registers lasting memory of the events of daily life personal: we speak of memory "episodic" literally translating English, but it is the memory of autobiographical events so personal , the correct term is "autobiographical memory."
Then, other neurons are affected by oil stain until the general collapse of the brain. It is due to this disorder early autobiographical memory that doctors and patients are alerted.
Two other neural systems of memory are allocated quickly semantic memory (general knowledge about the world and the ideas, famous people, for example) and working memory which brings together knowledge from many briefly to occasionally something complex: the short-term memory to a mental calculation example.
Signs and symptoms of memory problems pre-dementia
Long, up to 10 years before major signs, deteriorating brain appears only psycho-neurological tests. Nobody really notices unless arise in consultation Memory stock.
Then the circle can be noted blackouts particular, that the patient may have noticed but denied for fear of evoking the tragic event of dementia during the installation. Very recent events seem important and definitely forgotten by the patient: the birth or marriage of a small - a child, a close bereavement.
In fact, they are not forgotten, they were never saved. This never happens in memory loss by normal aging, in which case it is only the lability of attention (such as children) that makes lightly loaded small events of interest are not included.
Characteristically, in incipient Alzheimer's disease, the memory impairment is not reversible (never found the missing event) and it gets worse over time. It lies close memories to personal memories older.
Deterioration of semantic memory itself (which gives the meaning of things, concepts) that the patient can not answer a question "simple" like "what the sun and what is here? "This disorder semantics extends gradually stabilizing sometimes, but never regress. One day the patient does not know what is ... range when asked the question. This is especially noticeable in games like "Questions for a champion."
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