Alzheimer’s: Disease, Symptoms and Causes
Alzheimer’s disease is the most common cause of dementia. Dementia is a set of symptoms, like poor memory and difficulty in learning new information, which can make it really hard for a person to live independently. Dementia is caused because of cell damage in the brain. Alzheimer’s disease is a neurodegenerative disease, meaning it causes degeneration (or loss of neurons in the brain) — particularly in the cortex. These lead to symptoms characteristic of dementia.
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What is Alzheimer’s?
Two major conditions that are responsible for Alzheimer’s disease are Plaques and Tangles.
The amyloid precursor protein (APP) present on the cell membrane of a neuron helps it to grow and repair in case of an injury. Since APP is a protein, it gets used and, over a period of time, it is broken down and recycled. In unusual cases, insoluble monomers are chemically sticky and bond together outside the neurons — forming Beta-Amyloid plaques. These plaques get in the way of neuron-to-neuron signaling. If the brain cells can’t signal and relay information, then the brain’s functions (such as memory) can be impaired. These plaques can spike an immune response hence causing an inflammation that can damage surrounding neurons.
Tangles are found inside the cells. Neurons are held together by their cytoskeleton which is made up of microtubules (which transport nutrients and other molecules in the cell). The Tau protein maintains the microtubules. The Beta-Amyloid outside the neuron initiates signals inside the neurons causing the activation of kinase enzymes. Kinase enzymes transfer the phosphate groups on the Tau proteins, causing them to change shape, stop supporting the microtubules, and gather at one place forming tangles called Neurofibrillary Tangles. Neurons with tangles and nonfunctioning microtubules are unable to signal and sometimes undergo Apoptosis.
Sporadic Alzheimer’s Disease:
Described as a late-onset type, where the exact cause isn’t very well defined and is a combination of genetic and environmental risk factors. Sporadic accounts for the vast majority of cases. In Sporadic Alzheimer’s disease, the risk increases significantly with age. It affects around 1% of people between the ages between 60-65 and 50% of people at the age of 85. A gene has been identified which indicates an increased risk of this called e4 allele apolipoprotein E (AP0Ee4)
Familial Alzheimer’s Disease:
Cases where some dominant gene was inherited that speeds up the progression of the disease. Familial Alzheimer’s disease is also referred to as early-onset Alzheimer’s. Familial Alzheimer’s accounts for about 5-10% of cases and is caused by several gene mutations, like mutations PSEN-1 on chromosome 14 and PSEN-2 on chromosome 1. These genes encode presenilin 1 and presenilin 2 .
Both proteins form the subunits of γ-Secretase. Mutations in PSEN-1 OR PSEN-2 genes can change the location where γ-Secretase chops APP, producing different lengths of Beta-Amyloid molecules which then clump to form plaques.
Another known genetic cause of Alzheimer’s disease is trisomy 21, or Down Syndrome. It involves an extra copy of chromosome 21. The gene responsible for producing APP is located on chromosome 21. There is an increased expression of the APP gene resulting in an increased amount of plaque built up. For this reason, familial Alzheimer’s disease often progresses by age 40 in patients with Downs Syndrome. Symptoms of Alzheimer’s disease worsen as plaques and tangles develop and damage the neurons.
- In the early stages, symptoms might not even be detectible. As it progresses, patients lose short-term memory.
- Memory problems become more severe causing confusion and disorientation.
- Issues with motor abilities, particularly problems in language and speech
- Changes in the personality that become aggressive, demanding, or suspicious of others
- Low mood and anxious feelings
A diagnosis of Alzheimer’s Disease is difficult to make. Usually, a clinician will make a diagnosis after excluding other causes of dementia. Currently, there is no cure for Alzheimer’s Disease. Some medications exist but the benefits are small. There haven’t been any medications that clearly and definitively halt it.
Treatment Options for You
Alzheimer’s has no cure but can be managed with the help of treatment with medicines like Acetylcholinesterase (AChE) inhibitors, Donepezil, galantamine, and rivastigmine. Various other types of support are available to help people — like making accommodations at home so that it’s easy for them to move around and remember daily tasks.
Cognitive stimulation, which is a psychological treatment, can be utilized to support memory, problem-solving skills, and language ability.
Reminiscence work involves talking about the events that happened in the past. It’s often best to include props such as photos, favorite possessions, or music. Life story work is also one of the important aspects of managing Alzheimer’s.
- What is the prevalence of Alzheimer’s Disease? Globally it is estimated that around 50 million people suffer from dementia, where 70% of cases are caused by Alzheimer’s disease.
- What is the difference between memory loss due to aging and memory loss associated with Alzheimer’s disease? In normal memory loss, forgetfulness does not interfere with normal daily activities. In contrast, in Alzheimer’s disease, there is a marked and persistent memory loss that disables more intellectual abilities like judgment, abstract reasoning, etc.
Healthier Me Today is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment, always consult with your healthcare professional. Stay healthy!