Alzheimer’s and Its Symptoms
Alzheimer’s is a degenerative disease that alters the brain permanently and hinders the sufferer's ability to think clearly, remember things, carry out daily tasks and causes irrational behavior. Those suffering from the disease will progressively get worse. Early symptoms of Alzheimer’s usually involves difficulty remembering newly learned information, other symptoms can then include disorientation, the inability to recognize familiar faces and irrational mood and behavioral changes (What is Alzheimer’s, n.d.). Alzheimer’s is caused by the buildup of abnormal deposits of certain proteins within the neuron, which form plaques and tangles within the brain and causing healthy neurons to stop functioning properly and die off at a rapid rate. As the disease progresses, the person suffering will lose the ability to take care of themselves and will need constant assistance.
The Main Causes, Known Genes, and Risk Factors of Alzheimer’s
Alzheimer’s is caused by the abnormal buildup of beta-amyloid 42 and neurofibrillary tangles within the brain. In a healthy brain, amyloid protein fragments are broken down and eliminated by the body; in patients suffering from Alzheimer’s, these protein fragments accumulate within the brain to form insoluble plaques that hinders a neuron's ability to function properly (Amyloid and Neurofibrillary Plaques, n.d.). Neurofibrillary tangles are made up of a protein called tau. In healthy people, the tau protein functions to stabilize microtubules, which functions to transport nutrients and important molecules throughout the neuron. With Alzheimer’s, abnormal chemical changes causes tau molecules to break off from microtubules and attach to other tau molecules, creating neurofibrillary tangles within the brain. These tangles prevent the neuron from exporting signals and halts the synaptic communication between neurons. The buildup of amyloid plaques and neurofibrillary tangles normally begins in the Hippocampus, the area of the brain associated with memory. As the disease progresses, neurons will gradually die off and spread to the cerebral cortex, the portion of the brain responsible for language, reasoning and social behavior. The disease will continue to spread to other critical parts of the brain before leading to death.(What Happens to the Brain in Alzheimer’s Disease?, 2017).
There are many theories and genes that are thought to be associated with Alzheimer’s, however, there is no single explanation as to what causes the disease itself. Alzheimer’s is believed to be a multifactorial disease and there could be different variables that can play into the cause of the disease. One such theory is a defective TREM2 gene. Microglia functions in the brain by removing waste products through phagocytosis. It is believed that when microglia fails to clear away waste, debris and protein buildup within in the brain, it can lead to the accumulation of beta-amyloid plaques and cause chronic inflammation within the brain. TREM2 is a protein that normally tells microglial cells and astrocytes to clear amyloid plaques from the brain. Defects with the gene can send signals to microglial cells and astrocytes to collect around neurons, but not carry out their normal waste removing function. Instead, these cells will release chemicals that causes chronic inflammation and further damage neurons. Another theory is that vascular issues within the body can lead to a faulty blood-brain barrier, preventing glucose and oxygen from reaching the brain properly. Vascular issues can contribute to the buildup of amyloid and tau proteins as they aren’t being cleared away properly due to the faulty blood-brain barrier. Accumulation of these molecules can result in more inflammation and results with more vascular issues within the brain (What Happens to the Brain in Alzheimer’s Disease?, 2017). The APOE ε4 gene is the only gene known so far that is associated with an increased risk of developing Alzheimer’s, unfortunately, this allele is not associated with an increased buildup of amyloid plaques within the brain and it is not known how it is related to the increased risk of Alzheimer’s. Located on chromosome 19, it is known that inheriting one copy of the APOE ε4 gene increases your risk for the disease, and inheriting two copies of the gene even further increases the risk of developing Alzheimer’s later on in life (APOE gene, US National Library of Medicine, 2008).
How Alzheimer’s is Diagnosed
The first step in diagnosing Alzheimer’s involves a physical exam from your primary care doctor. The doctor will ask basic questions about family history, medical history, when did symptoms begin, what medications the patient is currently on, and may order blood and urine tests to rule out any other treatable conditions. Blood tests are usually conducted to check for any vitamin B12 deficiency or to measure the presence of TSH in the blood stream to rule out any abnormal thyroid function that may presenting symptoms similar to that of Alzheimer’s (Diagnosing Dementia, 2017). The primary care doctor will then refer the patient to a neurologist, who might order cognitive and neurophysical tests to measure the patient’s ability to remember things, solve problems and observe other cognitive abilities related mental functioning. Neurophysical tests are standardized tests where the score of the patient is compared to the score of a healthy individual with a similar background. A neuropsychologist will look at all the data from the neurophysical examination to determine a pattern of cognitive strengths and weaknesses that are associated in patients with Alzheimer’s (Neuropsychological Evaluation FAQ, n.d.). A neurologist may also order a brain scan to identify any previous strokes, tumours, or changes in brain structure and shape that may cause the development of Alzheimer’s. Either a CT scan, which takes multiple X-rays to produce images of the brain, or an MRI, which uses magnetic resonance to provide detailed images of the brain, can be ordered to view the anatomical structure of the brain. Both a CT and MRI scan can reveal the loss of brain mass that is commonly associated in patients suffering from Alzheimer’s (Recognizing and Diagnosing Alzheimer’s, n.d.). A PET scan uses radiation to provide pictures of brain activity and can reveal deficits that are common in Alzheimer’s, such as frontotemporal lobar degeneration. The PiB PET tracer is a recent innovation still in experimental trial that has been shown to bind specifically to amyloid deposits in the brain and reveal the presence of Alzheimer’s in a PET scan (Recognizing and Diagnosing Alzheimer’s, n.d.).
Main Treatments for Alzheimer’s
There is no cure for Alzheimer’s, there are only treatments that try to help improve the quality of life for those suffering from the disease. Cholinesterase Inhibitors are commonly prescribed to patients in early to moderate stages of Alzheimer’s. They delay and slow the worsening of cognitive symptoms of Alzheimer’s by preventing the breakdown of acetylcholine, by keeping acetylcholine levels high, this medication helps supports communication in nerve cells important for learning and memory. Memantine is another medication commonly prescribed to patients suffering from moderate to severe Alzheimer’s. It helps improve mental function and the ability to perform daily tasks by regulating glutamate activity, a neurotransmitter responsible for information processing, storage and retrieval. Evidence has shown that patients taking cholinesterase inhibitors have also benefited from taking memantine in conjunction (Medications for Memory Loss, n.d.).
Current Research
It has been discovered that THC can be used a potential therapeutic drug for patients with Alzheimer’s. Recent research has discovered that THC directly interacts with the amyloid peptide by lowering the levels of glycogen synthase kinase-3β. This kinase is thought to directly promote amyloid protein production and the buildup of neurofibrillary tangles in patients with Alzheimer’s. At low concentrations, THC is effective at lowering glycogen synthase kinase-3β and is a serious candidate as a potential therapeutic drug in the near future (The Potential Therapeutic Effects of THC on Alzheimer’s Disease, 2014).
Other types of research on Alzheimer’s have been focused on reversing the classic symptoms of Alzheimer’s by using a magnetic resonance imaging-guided focused ultrasound. This machine temporarily opens the blood brain barrier to allow the more effective delivery of drugs. The research was conducted on transgenic mice, which serves as an animal model for Alzheimer’s disease. After focused ultrasound treatment, these mice have been shown to develop improvements in cognition and spatial learning and have an increased neuronal plasticity . Scientists believe that these cognitive improvements are the result of reduced plaque and increased neuronal plasticity due to the ultrasound treatments.
References
Alzheimer's Association. (n.d.). Alzheimer's Disease & Dementia. Retrieved October 26, 2017, from https://www.alz.org/alzheimers_disease_what_is_alzheimers.asp
Alzheimer's Association. (n.d.). Latest Medication for Memory Loss. Retrieved October 26, 2017, from https://www.alz.org/alzheimers_disease_standard_prescriptions.asp#cholinesterase
Alzheimer's Association. (n.d.). Treatments For Behavioral Symptoms. Retrieved October 26, 2017, from https://www.alz.org/alzheimers_disease_treatments_for_behavior.asp
Bright Focus Foundation. (2017, June 21). Amyloid Plaques and Neurofibrillary Tangles. Retrieved November 16, 2017, from https://www.brightfocus.org/alzheimers/infographic/amyloid-plaques-and-neurofibrillary-tangles
Bright Focus Foundation. (2017, May 23). Possible Causes of Alzheimer's Disease. Retrieved October 26, 2017, from https://www.brightfocus.org/alzheimers/article/possible-causes-alzheimers-disease
Cao, C, Li, Y, Liu, H, Bai, G, Mayl, J, Lin, X, . . . Cai, J. (2014). The potential therapeutic effects of THC on Alzheimer's disease. Retrieved October 26, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/25024327
Harvard Health Publications. (n.d.). Recognizing Alzheimer’s Disease. Retrieved October 26, 2017, from https://www.helpguide.org/harvard/recognizing-and-diagnosing-alzheimers.htm
Meade, J. (2015, October 27). Attacking Alzheimer's with Ultrasound. Retrieved October 26, 2017, from https://www.nibib.nih.gov/news-events/newsroom/attacking-alzheimer%E2%80%99s-ultrasound
National Library of Medicine. (n.d.). APOE gene – Genetics Home Reference. Retrieved October 26, 2017, from https://ghr.nlm.nih.gov/gene/APOE#conditions
National Institute of Aging. (n.d.). Diagnosing Dementia. Retrieved October 26, 2017, from https://www.nia.nih.gov/health/diagnosing-dementia
National Institute of Aging. (n.d.). What Happens to the Brain in Alzheimer's Disease? Retrieved October 26, 2017, from https://www.nia.nih.gov/health/what-happens-brain-alzheimers-disease
UNC School of Medicine Neurological Department. (2017, October 10). Neuropsychological Evaluation FAQ. Retrieved October 26, 2017, from https://www.med.unc.edu/neurology/divisions/movement-disorders/npsycheval