Alzheimer’s disease is the most regular type of dementia. This disease is degenerative, incurable and terminal. It was first explained by Alois Alzheimer, a German neuropathologist, and psychiatrist in 1906, after which this terminal condition was named after him. It is said that after the age of 65 people are diagnosed with Alzheimer but the disease can also occur earlier during the lifetime of a patient. About 26.6 million people were suffering from Alzheimer’s in the year 2006. It is predicted that by the year 2050 there will be 1 in 85 patients with Alzheimer’s.
Quite a lot of theories exist which tries to explain why and how the disease occurs.
One of the oldest hypotheses is called the cholinergic hypothesis. Most of the prevalent drug therapies are based on this hypothesis. The hypothesis suggests that due to the reduction of the synthesis of the neurotransmitter acetylcholine in the body leads Alzheimer’s. This cholinergic hypothesis has not received widespread acceptance because the medicines which treat on the basis of this hypothesis have not proven to be effective.
The amyloid hypothesis states that the fundamental cause of the disease is deposits of amyloid beta. But in 2009 the theory was revised and it was stated that the cause of the disease might not be Beta-amyloid protein but a close relative of it.
In 2004, the tau hypothesis, says that the abnormalities which start the flow of the disease are caused by tau proteins. It is said that neurofibrillary tangles are formed inside nerve cell bodies when hyperphosphorylated tau couple with other tau threads. Thus the microtubules collapse and the transport system of neurons disintegrate.
A different hypothesis suggests that the causal factor of Alzheimer’s might be the breakdown of myelin in the brain due to age. When there is axonal transport disruption which is caused by demyelination it leads to neurons becoming stale. What the myelin breaks down due to iron release it affects the condition further.
Alzheimer’s causes the loss of Synapses and neurons in cerebral cortex and specific subcortical regions. Degeneration of the parental and temporal lobe, cingulated gyrus and parts of the frontal cortex which is resultant of the loss. Many studies using PET (Positron emission tomography ) and MRI (Magnetic resonance imaging) show decline in the size of the specific region of a brain as the patient goes commences from cognitive injury which is mild to Alzheimer ’s Disease
it is also called a disease which is seen as a disease caused due to protein misfolding. These are said to appear due to the folded tau and A-Beta proteins in the brain. Alzheimer ’s Disease is the accumulation of tau protein and thus is also a tauopathy
when beta amyloid is accumulated and produced and when Alzheimer’s is caused is not known. The hypothesis has told us that neuron degeneration mostly happens due to beta amyloid peptides accumulation which is considered to be the main factor for this event. it is also at times said that many process of inflammation and cytokines might have a role to play in the causation of Alzheimer ’s Disease