Potential biomarkers for the diagnosis of Alzheimer’s disease
In a study published this week in Nature Neuroscience, Bess Frost, PhD, and co-authors, identify abnormal expression of genes, resulting from DNA relaxation, that can be detected in the brain and blood of Alzheimer’s patients.
The protein tau is involved in a number of neurodegenerative disorders, including Alzheimer’s disease. Previous studies have implicated DNA damage as a cause of neuron, or cell, death in Alzheimer’s patients. Given that DNA damage can change the structure of DNA within cells, the researchers examined changes in DNA structure in tau-induced neurodegeneration. They used transgenic flies and mice expressing human tau to show that DNA is more relaxed in tauopathy. They then identified that the relaxation of tightly wound DNA and resulting abnormal gene expression are central events that cause neurons to die in Alzheimer’s disease.
The authors write, “Our work suggests that drugs that modify DNA structure may be beneficial for treating Alzheimer’s Disease.” The authors recommend, “A greater understanding of the pathway of DNA relaxation in tauopathies will allow us to identify the optimal target and explore the therapeutic potential of epigenetic-based drugs.”
Alzheimer’s disease is an irreversible, progressive brain disease that slowly destroys memory and thinking skills, and eventually even the ability to carry out the simplest tasks. In most people with Alzheimer’s, symptoms first appear after age 60. Estimates vary, but experts suggest that as many as 5.1 million Americans may have Alzheimer’s disease.
Alzheimer’s disease is the most common cause of dementia among older people. Dementia is the loss of cognitive functioning - thinking, remembering, and reasoning - and behavioral abilities, to such an extent that it interferes with a person’s daily life and activities. Dementia ranges in severity from the mildest stage, when it is just beginning to affect a person’s functioning, to the most severe stage, when the person must depend completely on others for basic activities of daily living.
Alzheimer’s disease is named after Dr. Alois Alzheimer. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. Her symptoms included memory loss, language problems, and unpredictable behavior. After she died, he examined her brain and found many abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now called neurofibrillary tangles). Plaques and tangles in the brain are two of the main features of Alzheimer’s disease. The third is the loss of connections between nerve cells (neurons) in the brain.
###
Getting a diagnosis
If you are concerned about your own health, or the health of someone close to you, it is important to seek help from a GP. An early diagnosis will have a number of benefits including the opportunity to plan for the future and access treatment, advice and support.
There is no straightforward test for Alzheimer’s disease or for any other cause of dementia. A diagnosis is usually made by excluding other causes which present similar symptoms. The GP will need to rule out conditions such as infections, vitamin deficiency, thyroid problems, depression and the side-effects of medication.
Specialists
The GP may ask a specialist for help in carrying out a diagnosis. The specialist may be an old-age psychiatrist, a neurologist, a physician in geriatric medicine or a general psychiatrist. Who the person sees will depend on their age, how physically able they are and how well services are developed in the local area.
Tests
The person being tested will usually be given a blood test and a full physical examination to rule out or identify any other medical problems. The person’s memory will be assessed, initially with questions about recent events and past memories. Their memory and thinking skills may also be assessed in detail by a psychologist.
A brain scan may be carried out to give some clues about the changes taking place in the person’s brain. There are a number of different types of scan, including computerised tomography (CT) and magnetic resonance imaging (MRI).
###
Jessica Maki
.(JavaScript must be enabled to view this email address)
617-525-6373
Brigham and Women’s Hospital