Pathophysiology of Alzheimer’s Disease
The core pathological findings in Alzheimer’s disease include extracellular amyloid
plaques, intracellular neurofibrillary tangles and neuronal degeneration. Amyloid plaques are a
cardinal feature of AD. They are complex structures which consist of a core of A amyloid
protein and surrounded by dystrophic dendritic processes (Serrano-Pozo, Frosch et al., 2011)
which are deposited in the cortex. This leads to neuronal damage of the medial temporal lobe
structures and the frontal cortex, consisting of the hippocampus. In the normal brain, the
protein fragments are usually eliminated. But in Alzheimer’s disease the fragments harden to
form plaques and accumulate in the brain. The
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These are intraneuronal aggregates of insoluble cytoskeletal protein,
formed from hyperphosphorylation of tau protein. Since the tau protein is abnormal in AD, the
microtubular functions are impaired. The other additional changes we can witness in the AD
brain include cerebral amyloid angiopathy, synaptic loss, Hirano body formation and
granuovacuolar degeneration (Perl D, 2010). Alzheimer’s disease is a slowly progressive disease
in which these lesions develop over many years and eventually lead to functional impairment.
(Parl, Lee et al., 2012). As a result of the changes in the brain, Alzheimer’s patients begin with a
decline in short term memory. Followed by alterations in mood and personality, progressive
disorientation, language dysfunction and apraxia. This causes the inability of the patient to care
for himself/herself and eventually causes them to be bedridden.
Genetics of Early vs Late of Alzheimer’s Disease
Early onset Alzheimer’s disease is usually seen among people 65 years and younger. It
accounts for about 6-7% of the cases (Ridge, Ebbert et al., 2013) of AD. Mutations in three
different genes are known to be the causal factor for Early onset AD. These genes
Percy, A. K. (1999). Inherited neurodegenerative disease: The evolution of our thinking. Journal of Child Neurology, 14(4), 256-62. Retrieved from
This is a disease is found in the brain and is caused by a buildup of a protein called tau. Tau slowly kills brain cells. Even after brain trauma has ended this process still continues. There are many symptoms such as memory loss, confusion, impaired judgement, depression, and even aggression.
Attention Deficit Hyperactivity Disorder (ADHD) is a developmental disorder that displays as distracted, hyperactive, and unable to focus on tasks and activities. Also known as Hyperkinetic Impulse Disorder, Hyperkinesis, Hyperactive Syndrome, Minimal Brain Damage, Minimal Brain Dysfunction, and Undifferentiated Deficit Disorder, ADHD is the most commonly diagnosed neurological disorder in children. Although many children with ADHD are quite intelligent, their lack of focus can frequently lead to poor grades and a low self esteem. The exact cause of ADHD is still unknown, but it is considered highly inheritable. Results from numerous international studies on twins have found that ADHD may have a genetic link. The occurrence of ADHD in one twin is more often mirrored an identical twin who has the same genetic makeup, then in a fraternal twin whose genetics are similar but not identical. It is also believed that if a parent, uncle, or grandparent had ADHD, it is more likely their family may develop it as well. No gene has been discovered that directly relates to the disorder. MRI studies comparing the brains of children with and without the condition have shown that children with ADHD have weaker brain activity in the frontal area of the brain when responding to tasks that require inhibition. Because of this, it is thought that ADHD affects certain sections of the frontal cortex, parietal lobe, and possibly parts of the cerebellum.
There are seven stages of Alzheimer’s, classified by Dr. Barry Reisberg, M.D. clinical director of the New York University School of Medicine’s Silberstein Aging and Dementia Research Center. Each stage carr...
Memory plays a significant role in the everyday lives of people of all ages. It allows them to recall information and remember skills that were learned in the past. Memory also organizes past information to help people make current and future decisions. However, imagine forgetting the names of close family members or not having the ability to find your keys every time you want to leave the house. These are some of the struggles that people with Alzheimer’s disease face daily. Alzheimer’s disease was first identified by German neurologist Alois Alzheimer in 1906, and was discovered to have an overpowering effect on explicit memory loss (Gruetzner, 1988). There are two types of Alzheimer’s disease – early onset and late onset. Early onset occurs in patients who are diagnosed before the age of 65 whereas late onset occurs in patients who are diagnosed after the age of 65. In the early stages of Alzheimer’s disease, short-term memory is often lost. As Alzheimer’s disease progresses, problems with long-term memory begin to develop, in addition to short-term memory impairments. Although a lot is known about the symptoms of Alzheimer’s disease, the cause has not been conclusively identified. However, as research continues, new theories about the cause of Alzheimer’s disease are being proposed. This has led to a controversy over whether Alzheimer’s disease is caused by genetics or environmental influences (Gruetzner, 1988).
of diagnosis is about 80 years old (Johnson, 1989). The incidence is about the same for all races, but women are more likely than men to develop the disease, because they live longer. The second factor is heredity. Family history plays a role in about forty percent of people with early onset of Alzheimer’s (Johnson, 1989). If your parents or a sibling developed the disease, you are more likely to, as well. But there are cases of families with several people who have had this disease and other members are not affected. These two factors are the only proven factors, but environmental research is being done to help with a possible protective effect for the disease. As of now, more research is needed to confirm any be...
There are definitely people with a genetic vulnerability. However, there are also others with biological vulnerabilities. ADHD is a real disorder with implications to problems with brain chemistry and function. It is also know to be one the most commonly diagnosed disorders in school aged children. Today we use brain scan studies and genetic studies to help us diagnose this disorder. However, we have learned that is a heterogenous disorder and is still a very low-tech diagnosis based on symptoms (Ullman,
Chronic Traumatic Encephalopathy, also known as CTE, is a neurodegenerative disease where an excess amount of tau, an abnormal protein, builds up inside of the brain. According to “A critical review of chronic traumatic encephalopathy”, the disease also creates “multiple blockages of the axonal transport to the brain cells, along with white spaces in the brain on a MRI scan.”, as
degeneration 3 A nerve cell has numerous axons and dendrites coming out of it. A neurofibrillary tangle is when the neuron changes. A number of dendrites are missing and the nucleus is filled with protein filaments resembling steel wool. Although all elderly people have a few of these helix shaped bundles in their brain as they are normal indicators of aging, Alzheimer's patients have. more than usual.
There are three stages towards Alzheimer’s and one should be aware of the important signs and symptoms. For instance, one should be aware of co...
“Alzheimer's disease is a progressive, degenerative disorder that attacks the brain's nerve cells, or neurons, resulting in loss of memory, thinking and language skills, and behavioral changes” (Alzheimer’s Foundation of America, 2014). AD is a debilitating disease that interferes with the individual’s quality of life and often causes distress to the loved ones around them. The cause of AD is unknown; however, there are some factors that put individuals at risk for developing AD such as: age (gre...
Alzheimer’s disease (AD) is a progressive, terminal, degenerative brain disease. It is the fourth leading cause of death in adults and currently affects over four million people in the United States. This number is expected to increase over the next several years as the baby boomers age, until it reaches fourteen million by the year 2025.
Since the gene for HD is dominant, there is a 50% chance of a sufferer's
Because A"β" is critical to the pathogenesis of Alzheimer’s disease, “it is imperative to understand the molecular and cellular basis of its production” (Bali 2010). The A"β" peptides themselves are formed from an Amyloid Precursor Protein, “ by the sequential action of of "β" - sycretase and "γ " secretase” and are released, forming plaques. The toxic properties of these plaques include the phosphorylation of tau, thus the creation of tangles in the brain, and neurodegeneration (Bali 2010).
Biology The brain consists of both neurons and glia cells. The neurons, which are cells housed in a cell body called a Soma, have branches which extend from them, referred to as dendrites. From these dendrites extend axons which send and receive impulses, ending at junction points called synapses. It is at these synapse points that the transfer of information takes place. At the heart of neuroplasticity is the idea of synaptic pruning.