Neurodegenerative disease

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at September 26, 2016
StartDiseasesNeurodegenerative disease

Neurodegenerative diseases affect a wide range of body functions. Breathing, swallowing, speech, balance, movement, and heart function may be impaired. There are treatments to relieve symptoms, but most degenerative nerve diseases are incurable. 

Contents

Definition & Facts 

Normally, nerve cells in the brain called motor neurons transmit messages to other cells in the brainstem and spinal cord. The nerve impulses then reach particular muscles throughout the body to produce movement. When degenerative nerve diseases attack and destroy motor neurons, their signals fail to reach muscles. Eventually, the muscles weaken and deteriorate.

Both voluntary and involuntary movements can be impaired. Depending on the disease, brain tissue can also be affected. Symptoms worsen as the disease progresses, and new symptoms can appear in later stages of illness. There are many neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis, also called ALS or Lou Gehrig’s disease.

Symptoms & Complaints

Symptoms vary according to which cells are destroyed. Alzheimer’s disease, for example, is marked by dementia which involves memory loss, difficulty constructing sentences, confusion, and disorientation. People with Alzheimer’s frequently lose their keys, wallets or other personal items. They may forget to bring in the mail or pay the bills.

The progression of the disease can create potentially dangerous situations. A patient may leave the stove on, forget to take his or her medication or get lost while driving.

Failure to recognize familiar people is also a common marker. Some patients become depressed or apathetic.

ALS symptoms usually start with weakness in the tongue or one hand. As the disease progresses, muscles can become stiff and movements can become clumsy. Gradual paralysis sets in. Fatigue, speech problems, drooling, severe unexplained weight loss, and difficulty swallowing (dysphagia) are not uncommon in later stages.

Symptoms of Parkinson’s disease include tremors, shaking, slowed movement and dragging the feet when walking. Getting out of a chair or a car is progressively more difficult. Muscle stiffness causes difficulties with balance and posture. Changes in speech and handwriting are evident. Muscle reflexes can become overactive.

Causes

The causes of motor neuron diseases continue to elude scientists. Alzheimer’s patients tend to be older people, but why some seniors get it and some don’t is a mystery. It is known that two kinds of nerve damage contribute to symptoms: tangled nerve cells and a buildup of protein deposits in the brain. One in particular, apolipoprotein E, might contribute to the plaque that forms between nerve cells and causes brain damage.

Other unproven theories suggest that high blood pressure (hypertension), high cholesterol (hypercholesterolemia) or traumatic head injuries play a role in causing Alzheimer's disease. Alzheimer’s does seem to run in families.

ALS involves genetic factors which play a role in 5-10 percent of cases. In inherited ALS, a genetic mutation affects production of an enzyme called superoxide dismutase (SOD1 or copper zinc sueroxide disumutase 1). That enzyme is responsible for getting rid of certain wastes that are created during metabolism. ALS can result from genetic mutations that cause this enzyme to become toxic. Researchers are looking into other possible causes of amyotrophic lateral sclerosis such as viral infection and exposure to environmental toxicants.

It is not known exactly what causes Parkinson’s disease, but patients have low dopamine levels. Between 15 and 25 percent of patients have a relative with the same disease. There are strong links between Parkinson’s and exposure to certain chemicals such as insecticides, herbicides and Agent Orange.

Diagnosis & Tests 

The doctor will inquire about the patient's medical history and family history. He or she will also perform a physical examination. Diagnosis of neurodegenerative diseases will involve neurological examinations to test the sensory and motor responses. Physicians will give memory tests and assess the degree of impairment.

They will evaluate cognitive thinking skills, behavior and personality through neuropsychological assessments. Medical imaging tests of the brain will be conducted. Such exams include magnetic resonance imaging (MRI) scans, computed tomography (CT) scans, and positron emission tomography (PET) scans.

ALS can only be diagnosed by observing symptoms and doing blood tests to rule out similar diseases. Doctors first look for signs of deterioration in upper and lower motor neurons. They will check the rate at which symptoms are affecting other parts of the body. Simple tests of nerve and muscle function are part of a neurological exam.

If the disease appears to be ALS, an electromyogram is done. It measures the signals that pass between nerves and muscles. A muscle tissue biopsy may also aid diagnosis.

Like most other neurodegenerative problems, there is no specific test for Parkinson’s. A patient's medical history, a study of symptoms, and physical and neurological exams give doctors a place to start. Some doctors prescribe a dose of carbidopa and levodopa, a drug used to improve symptoms and pain. If a patient shows improvement, it’s likely that he has Parkinson’s.

Treatment & Therapy

To date, there is no way to stop the progress of degenerative nerve diseases. However, symptoms can be stalled and patients made more comfortable. Some drugs have been shown to slightly improve cognitive skills and memory in Alzheimer’s patients. Ginkgo, omega-3 fatty acids and vitamin E have been tested with mixed results.

A safe environment is extremely important. Those caring for someone with Alzheimer’s should install hand rails and remove excess furniture. The patient should wear non-skid shoes. Items like keys, glasses and wallets should always be kept together in the same place.

Levodopa is used to treat Parkinson's. It is synthesized by the brain into dopamine of which Parkinson's patients have an insufficient amount. Carbidopa is used in combination with levodopa because it prevents the body from breaking down levodopa.

Symptoms of Parkinson’s can be improved with deep brain stimulation. In DBS, electrodes are implanted in certain areas of the brain. When they’re connected to a generator, electrical impulses travel to the brain and reduce symptoms.

The complaints of ALS are harder to treat, but certain drugs like antidepressants can help. New technological advancements that enable impulse-controlled speaking and typing have made it easier for paralyzed patients to communicate or continue working. For all motor neuron diseases, reguar exercise, healthy diet, and socialization improve symptoms and quality of life. 

Prevention & Prophylaxis 

Unfortunately, science has not yet found a way to prevent neurodegenerative disease. Research is ongoing, and scientists continue to come close to solutions. A promising new gene therapy for ALS was unveiled only recently. The medical community is hopeful that more studies in molecular and cellular biochemistry will soon provide answers.