Alzheimerâ€™s disease is a chronic progressive neuro-degenerative disorder characterised by three primary groups of symptoms. The first group (cognitive dysfunction) includes memory loss, language difficulties, and executive dysfunction (that is, loss of higher level planning and intellectual coordination skills). The second group comprises psychiatric symptoms and behavioural disturbances â€” for example, depression, hallucinations, delusions, agitation â€” collectively termed non-cognitive symptoms. The third group comprises difficulties with performing activities of daily living (deemed â€śinstrumentalâ€ť for more complex activities such as driving and shopping and â€śbasicâ€ť for dressing and eating unaided).â€ś
Source : BMJ 2009;338:b15
Alzheimerâ€™s (abbreviated as AD) is the most common cause of dementia, with an estimated 30 million sufferers worldwide at any one time. The cause of Alzheimerâ€™s disease is unknown.
For many years, it was thought that the 'amyloid plaques' (buildup of abnormal peptide proteins) which form in the brains of AD sufferers, was a primary cause of the dementia. It's now thought more likely that the plaques are as a result of the disease, or even that they are a protective agent which forms due to natural defence responses by brain neurons.
Note that recently approved drugs (e.g. Lecanemab) which can help slow the buildup of the plaques, are not proving very effective in halting the progress of the disease.
Current opinion is leaning towards the idea that AD might be triggered by an infectious agent of some kind - perhaps a virus or a bacterium Various candidate organisms are being investigated, including the Epstein Barr virus, the herpes simplex virus 1 (present in around 70% of the population), and a bacterium which causes gum disease. At present, no infectious agent has definitely been identified as a cause.
See Nature, news feature, Nov. 2020
Further information Alzheimer's Society, UK
Also see :and
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