What is Alzheimer's disease?

What is Alzheimer’s disease?

With approximately 44 million people suffering from it worldwide, Alzheimer’s is one of the most common neurological disorders and the most common type of dementia. Dementia refers to the loss of certain brain functions such as memory, thinking or reasoning to the point where it compromises one’s daily actions. In the case of Alzheimer’s latest stages, people can have trouble living within society as they can experience agitation, aggression or hallucinations and a huge range of different symptoms. Alzheimer's is also one of the most fascinating disorders of medicine as we have very little understanding of this disease and neurologists are working all around the world to research this bewildering condition.

Symptoms

Scientists have discovered two different types of this dementia, early-onset and late-onset. Early onset is the rarest form of Alzheimer’s, its symptoms usually start between a person’s 30s and 60s, and late-onset symptoms generally start in the mid-60s.

The main symptom of this disorder is the impairment of memory. In early stages, symptoms can be as basic as getting lost in familiar places, speech and language impairment, personality changes, hallucinations (especially of objects from the past), and problems with performing self care tasks. For people suffering from early-onset, the first symptoms are usually struggling to read or judge distances, difficulty with language or even problems with planning and decision making.

As the disease develops new symptoms start to appear, such as inability to learn new things, difficulty with logical thinking and working with numbers, problems with carrying out multi step tasks, difficulty recognising family and friends, paranoia, impulsive behaviour or outbursts of anger. At this point, people suffering from the disease can have difficulty living on their own and need constant assistance.

Unfortunately more symptoms develop as the disorder progresses and begins its last stages, we can expect weight loss, seizures, skin infections, difficulty swallowing or loss of bowel and bladder control. People also tend to develop behavioural and psychological symptoms of dementia (BPSD) which include anxiety, agitation, hallucinations or even aggression .

Of course, death is also one final symptom of Alzheimer’s, there are many reasons why patients can die from the disease. The most common cause of death is aspiration pneumonia where patients can’t swallow properly and injects food or liquids into their lungs. Other causes can be simple infections that could easily be treated in healthy patients but people suffering from dementia can forget to take medicine or to get help if they are sick.

Causes

What is so dangerous about Alzheimer’s disease is that first damage to the brain tends to appear 10 years before the first actual symptoms. Yet scientists do not still fully understand the causes of Alzheimer’s disease but past and ongoing research helps us understand some of the causes and risk factors of dementia. The causes for early-onset and late-onset are similar but some causes are more frequent for young-onset patients. For example, it is thought that the earlier the disease starts, the most likely that the disease is genetic.

Scientists have discovered that the main cause of Alzheimer’s is linked to two proteins: beta-amyloid and tau. Somehow, Alzheimer’s causes tau to accumulate and create tangles inside neurons which harms the communication between brain cells while beta-amyloid forms plaques between neurons that endanger cell function. But it is believed that these two proteins aren’t the sole cause of dementia.

Chronic inflammation is thought to be another cause of the disorder and is given rise by microglia cells. Microglia is a cell that helps clear debris in the brain and scientists think that Alzheimer’s compromises this cell’s function, making it unable to clear the brain of debris such as amyloid plaques. It actually makes it even more toxic to the brain by releasing chemicals that cause chronic inflammation and damage neurons.

It is believed that vascular problems may also contribute to Alzheimer’s disease. Indeed, they could lead to difficulty with oxygen and blood flow to the brain and break the blood-brain barrier which is a filter of what goes in the brain, preventing harmful agents from passing through while allowing glucose and other beneficial agents to access the brain.

Finally, the symptoms are triggered by the death of neurons due to the causes explained above that break connections throughout the brain, causing certain areas, especially the hippocampus, partly responsible for memory, to shrink. This process is called brain atrophy and patients in the final stages of dementia experience significant brain volume loss, which causes the final symptoms.

Treatment

There isn’t and probably never will be a cure for Alzheimer’s, but scientists are working to develop drugs to help patients suffering from the disease. The approved drugs to treat this disorder mainly treat the symptoms by delaying its progression.

The main medicines prescribed for Alzheimer’s patients are Memantine and Acetylcholinesterase (AChE) inhibitors such as Donepezil, galantamine and rivastigmine. Memantine is used for early/mid stages of Alzheimer’s, and is fitted for patients that do not respond well to Acetylcholinesterase (AChE) inhibitors, but it also fits people with late-stage Alzheimer’s when combined with the inhibitors. It works by regulating the amount of glutamate, a chemical in the brain which, if in excessive amounts, causes brain cell death. This drug is believed to treat symptoms and enable people to carry out daily actions on their own for a little longer.

Acetylcholinesterase (AChE) inhibitors are also recommended for patients with mild to moderate Alzheimer’s, they are designed to help neurons communicate with each other therefore delaying the symptoms.

Drugs to treat behavioural and psychological symptoms of dementia have also been developed, the only approved ones for patients with dementia are risperidone, haloperidol and antipsychotic medicines.

A single disease-modifying drug (medication that targets the causes of a disease) has been approved for Alzheimer’s, it is called Aducanumab. It is an immunotherapy and targets amyloid plaques explained in the causes above. Other disease-modifying drugs and therapies are currently being researched to treat the disorder.

Finally, a few treatments that involve therapies and activities are cognitive stimulation therapies and cognitive rehabilitation are also recommended.

Conclusion

Alzheimer’s disease is a horrible yet fascinating condition that affects millions of people around the world. With symptoms ranging from mild memory loss to hallucinations, patients suffering from the disorder can be forced to have full time assistance and lose their independence completely. Although, with hundreds of scientists researching this dementia, we are hopeful for an improved understanding of its causes leading to better ways of helping these people with cutting-edge treatment and medication. Ongoing research everywhere in the world makes us hope for a better future for Alzheimer’s patients.