Aging and Disease

The true causes of Alzheimer’s disease remain elusive. However, researchers have made progress in understanding the neurological roots of this debilitating condition.

The disease is named after Alois Alzheimer, who was the first to identify the peculiar plaques and tangles in the brain, which is characteristic of the illness. Till the final decades of the twentieth century, Alzheimer’s could be diagnosed accurately only by a post-mortem examination.

Nowadays, scientists are beginning to uncover precisely what is happening and why those characteristic tangles and plaques crop up in the brain.

Many of the symptoms of Alzheimer’s disease are caused by neurofibrillary tangles in the brain. Microscopic filaments clog the neurons. These filaments are made up of an abnormal kind of Tau protein.

In a normal brain, Tau protein bonds into microtubules and enables transmission of messages from one neuron to another. But in an Alzheimer brain, instead of bonding into message pathways, Tau protein bonds with itself. And the neuron messages go nowhere.

Since the neurons are clogged, signals from the environment are no longer transmitted the way they should be. That is why severe cognitive impairment is one of the symptoms of Alzheimer’s disease.

Scientists speculate that Tau protein malfunction which results in neurofibrillary tangles is caused by beta amyloid protein, but this is yet to be conclusively proved.

It is beta amyloid protein that causes plaques between neurons, which is the other main damage to the brain in Alzheimer’s disease.

The plaque deposits are sticky patches in the brain which contain beta amyloid protein. Plaque blocks communication pathways between neurons, which results in the memory problems and learning inabilities associated with Alzheimer’s disease.

The degree of cognitive impairment depends on the amount of plaque present. Plaque acts by interfering with the normal functioning of acetylcholine, which helps to transmit nerve messages.

Treatment for Alzheimer’s disease involves using acetylcholinesterase inhibitors, which works by blocking enzymes that consume the acetylcholine. This medication is effective during the early stages of the disease before too much plaque has already built up.

Some research seems to indicate that plaques cause tangles. One study took proteins from mice to eliminate the plaque-causing beta amyloid. They found that the proteins got rid of the tangles as well. Similar effects have been brought about by other medications as well.

Others believe that both plaques and tangles are the result of other processes. One possible culprit is swollen axons. Axons are critical for transmitting messages between neurons. When axons swell, they may block message transmission and perhaps lead to the plaques and tangles which bring on Alzheimer’s disease.

Scientists are working hard at uncovering the causes of Alzheimer’s disease, which may sooner or later lead to a comprehensive cure for this dreaded condition.

Tags: Aging, Disease

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