Tau Brain Scans
The deadly disease Alzheimer's takes a terrible toll on not just memories but also lives of millions year on year. Although doctors use checklists of symptoms and signs to detect Alzheimer's, these methods are open to major variations in medical opinion about a single patient. There is a danger of Alzheimer's disease - AD - being confused with any other dementia or common declining intellectual disabilities.
Sometimes, memory loss need not be the first symptom of Alzheimer's and it could be behavioral or language changes or difficulty in everyday activities. Hence, doctors treating Alzheimer are always left to face uncertainty in trying to diagnose the disease in the living, and only an autopsy can confirm the disease for certain.
A pioneering brain image - Tau brain imaging - can detect the build-up of destructive proteins linked to Alzheimer's. This is the beginning of diagnosing the condition and testing of new drugs. Reported in the journal Neuron, tau brain scan can identify living clumps of a protein called tau that is closely linked to the disease. With this new diagnosis, patients can be helped early to make the most of their remaining life span. This definitive diagnosis can tell Alzheimer's disease apart from other disorders.
To understand this, it is relevant to know that Alzheimer's patients lose their brain's nerve fibers and there is an abnormal buildup of protein that damages nerve cells. Patients who begin with mild memory loss soon worsen to become restless, anxious, confused and moody. Patients lose their ability to talk or care for themselves in the final stages.
Tauopathies are a set of neuro-degenerative diseases associated with phosphorylated tau protein aggregation in the human brain. In Alzheimer's, tau protein is deposited within the neurons as neurofibrillary tangles. The German psychiatrist and later Neuro pathologist Dr. Alois Alzheimer was the first to describe this disease as pre senile dementia.
It is the associated protein tau that causes the tangles to aggregate in an insoluble form. The tau protein is referred to as 'PHF' or paired helical filaments. There are other conditions as well in which such neurofibrillary tangles are observed and these include progressive supranuclear palsy, chronic traumatic encephalopathy, Parkinson-dementia complex, ganglioglioma, meningioangiomatosis and tuberus sclerosis among others. These non-Alzheimer's tauopathies are grouped as Pick's complex.
A protein called tau (τ) is very closely linked to Alzheimer's and tangles of tau are thought to be one way in which the brain cells are killed. Researchers have developed a chemical that could bind to tau and then be detected during a brain scan. This was tested on mice and people and it showed that suspected Alzheimer's could be revealed by this technology that could detect tau.
Dr Makato Higuchi, National Institute of Radiological Sciences, Japan says that this emission tomography image of tau accumulation provides robust information on brain regions and also risk for tau-induced neuronal death. Although this research is at an early stage, it could eventually lead to identifying Alzheimer's.
As another Alzheimer's expert says "Tau can be compared to railroad ties that stabilize a train truck that brain cells use to transport food, messages and other vital cargo throughout neurons. In Alzheimer's, changes in tau protein causes the tracks to become unstable in neurons of the hippocampus, the center of memory. Abnormal tau spreads from cell to cell, disseminating pathological tau in the brain cortex".
While researchers have already tried time-tested medical imaging techniques to detect this disease, and while magnetic resonance imaging and computed tomography scan only rule out other disorders, there is no positive detection tool for Alzheimer's. Tau imaging highlights a new method for detecting tau, which would be a key player in both Alzheimer's and frontotemperal dementia in the living brain. The tau scan is capable of visualizing the protein inside the brain and is important for assessing whether treatments in clinical trials are hitting the target.
If the tau scan is shown to be effective, then it could become a potential aid for providing people with accurate diagnosis for monitoring the disease progression. The new focus for Alzheimer's treatment is halting the toxic tau.
A set of researchers at the Mayo Clinic in the US were able to look at the evolution of tau using neuro pathologic measures. Just like one could identify the changing seasons by looking at the rings of a tree, and the aging of the tree by viewing the cross section, studying the different stages of Alzheimer's gives a perspective of the cognitive impact of a wide range of amyloids and tau severity. At the Mayo brain bank, a collection of thousands of post mortem brains have allowed to understand changes in tau and amyloid that occur over a period of time.
There is an estimated 3 to 4 million people in the US with some form of Alzheimer's and there is a tendency for the number to increase over the years. Therefore, a good diagnostic tool is a must. Tau imaging represents significant advancement in the field and it is hoped that combined tau and amyloid positive PET scans may in the future help researchers get closer to an affirmative diagnosis of Alzheimer's disease.
This is a rare degenerative disease, a fatal brain disorder. One in every million worldwide is affected by Creutzfeldt Jakob disease which occurs about age 60, and about 90 percent of patients die within a year. Since first described in 1920, less than 1 percent of cases have acquired CJD.
Signs and symptoms
During the early stages of the disease failing memory, behavioral changes, lack of coordination and visual disturbances are exhibited. Impaired memory, judgment and thinking and insomnia, depression or unusual sensations are other symptoms. CJD may also cause fever or other flu-like symptoms. As the illness progresses, mental deterioration becomes severe. Involuntary movements, blindness and weakness of extremities are other symptoms.
Rapidly the disease progresses into dementia. Patients eventually lose the ability to move and speak and then enter a coma. Pneumonia and other infections may occur in these individuals and can lead to death. Some symptoms of CJD can be similar to Alzheimers or Huntington disease. CJD causes unique changes in brain tissue which can be seen at autopsy and the deterioration is more rapid than Alzheimer's disease or other types of dementia.
Major categories of CJD
Sporadic CJD: Here the disease appears even though the person may not exhibit any known risk factors. This is by far the most common type of CJD and 85 percent cases come under this category.
Variant CJD is caused by consuming meat from a cow that had Bovine Spongiform Encephalopathy (BSE) or mad cow disease, a prion disease similar to CJD. Strict controls have proved very effective since its discovery in 1996.
In hereditary CJD, the person has a family history of the disease and tests positive for a genetic mutation associated with CJD. About 5 to 10 percent of cases in the US are hereditary and the symptoms usually develop in early 50s.
In latrogenic CJD, the infection spreads from someone through medical or surgical treatment. A common instance of this is spread of CJD from someone with growth hormone treatment using human pituitary growth hormones extracted from deceased individuals who might have had CJD infection.
CJD is not contagious through casual contact with a CJD patient.
Researchers believe that an unusual slow virus or any other organism causes CJD. But they have never been able to isolate a virus or any organism in people with the disease. As the agent causing CJD has several characteristics other than known organisms such as bacteria and virus, it is difficult to destroy as it does not contain any genetic information in the form of nucleic acids. For example, prions are not destroyed by the extremes of heat and radiation used to kill bacteria and viruses, and antibiotics or antiviral medicines have no effect on them. It also incubates for a long period of time before the symptoms appear, as long as even 50 years. The leading scientific theory maintains that CJD is caused by a type of protein called as a prion. Also 5 to 10 percent of CJD cases are inherited. These cases arise from a mutation, or change in the gene that controls formation of the normal prion protein.
Diagnosis of CJD
There is no single diagnostic test for CJD. First, all treatable forms of dementia are ruled out. A neurological examination is performed and consultation with other physicians is sought. Spinal tap, electroencephalogram, CT and MRI and brain scans can reveal characteristic patterns of brain degeneration that can help diagnose CJD.
For a confirmed diagnosis of CJD, brain autopsy is the only way. A neurosurgeon removes a small piece of tissue from the patient's brain and it is examined by a neuropathologist. The procedure may be dangerous as it does not always obtain tissue from the affected part of the brain. Brain biopsy is discouraged unless it is needed to rule out a treatable disorder. In autopsy, the whole brain is examined after death. Special surgical and disinfection procedures can minimize the risk. Scientists are working to develop laboratory tests for CJD.
As such there is no treatment or cure to control CJD. Studies are on to try a variety of drugs but none of the treatments have shown consistent benefits in humans. Treatment aims at alleviating symptoms and making the patient as comfortable as possible. Opiate drugs can help relieve pain. During later stages of the disease, changing person's position frequently can keep them comfortable and help prevent bed sores. A catheter is used to drain urine if bladder control is lost. Intravenous fluids and artificial feeding are also used.
Avoid spreading CJD
To reduce the very low risk of CJD transmission from one person to another, it is better not to donate blood, tissues or organs if suspected or confirmed with CJD because of family history of the disease. As normal sterilization procedures such as cooking, washing and boiling do not destroy prions, the following precautions are suggested by the World Health Organization while dealing with patients contacted with CJD.
This is a less common form of dementia, more prominent in those under the age 65. Frequently misdiagnosed as Alzheimer's disease, Pick's patients initially exhibit marked personality and behavioral changes. And gradually the ability to speak coherently declines.
Although there is no cure for Pick's complex presently, it can however be managed well and the quality of life improved. According to Arnold Pick, who first described the disease in 1892, Pick's disease causes an irreversible decline in a person's functioning for several years. Pick's affects adults between the ages of 40 and 60 and is more common in women than men.
The frontal and temporal lobes of the brain control a person's speech and personality. Excess protein build-up in these parts causes slow atrophy in these regions. The cause for this build-up of protein is unknown. Other than causing speech and behavioral changes, Pick's disease can also cause memory loss quite like those with Alzheimer's as well as socially inappropriate behavior, poor decision making, progressing to severe impairment in intellect, speech and memory. Some opine that Pick's disease may have a genetic or heredity component although not all family members are affected.
Symptoms of Pick's disease
The first sign of Pick's complex is personality changes and decline of basic functioning. Pick's can occur in an age earlier than Alzheimer's and memory loss need not be a predominant early sign of Pick's disease. Although there could be reports of Pick's occurring as young as 20 years of age, the progression is slower in Pick's disease. However, there are cases where symptoms could worsen over time and brain cells degenerate. More severe symptoms appear at later stages of Pick's. Some noticeable behavioral symptoms of Pick's disease are poor judgment, extreme restlessness especially in the early stages, overeating or drinking, lack of personal hygiene, sexual exhibitionism, decreased interest in daily activities and obsessive behavior.
Mood swings, lack of empathy, apathy, rudeness, impatience and aggression, easy distraction and being unaware of strange behavior and memory loss are some of the prominent emotional symptoms of Pick's disease. Loss of vocabulary, difficulty in speaking and understanding, uncoordinated speech and decrease in the ability to speak and write are some serious signs of Pick's.
Diagnosis of Pick's Complex
Other than careful symptomatic evaluation, brain scans and EEG, three of the following five characteristics are found to be present in the early stages. They include:
Diet and activity
There should be a restriction on foods with high sugar content. There could be carbohydrate cravings in some. While in Alzheimer's and Parkinsons, a diet relatively high in fat and protein and low in carbohydrates is necessary, it is unclear if the same is recommended for Pick's complex. It is better to get a doctor's opinion on an appropriate heart-healthy diet. A regimen of therapeutic exercises such as brisk walking can help to regulate the patient's mood and benefit on cognitive function.
Pick's disease, like any other dementia progresses rapidly and life gets shortened about six to eight years, although some do live for as long as twenty years. As currently there is no cure for Pick's like Alzheimer's, the aim is to maximize quality of life by way of medications to manage particular symptoms, regular supervision, and assistance.
Emotional and substantive support is an important aspect of the treatment. The family of the affected may help with the following control symptoms:
Tips for coping with Pick's complex
Being diagnosed with Pick's complex can be overwhelming especially when it involves any form of dementia. It is good to learn more about Pick's disease and frontotemporal dementia. In this way, more control can be exhibited and they will be better prepared to manage symptoms.
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Diseases, Symptoms, Tests and Treatment arranged in alphabetical order:
Bibliography / Reference
Collection of Pages - Last revised Date: June 13, 2021