The loss of myelin is a normal feature of aging. Though scientists aren’t exactly sure why this protective sheath breaks down with age, recent studies have indicated that certain proteins in the brain may cause the cells that produce myelin to die. Aside from this natural contributor to myelin loss, certain diseases, including multiple sclerosis, cause this condition and the deterioration in neural function associated with depleted myelin.
Though the complicated processes that cause aging are not well understood, most of the body’s systems undergo some loss of function and deterioration as a person gets older. Brain function can deteriorate significantly with age, often due to a loss of myelin that normally coats neurons and allows electrical signals to travel quickly through the neural network. Much of this loss can be attributed to a protein known as DR6. This messenger instructs the cells that coat neurons with myelin to die without replicating. When the brain has fewer of these cells, it is unable to keep up with the task of re-coating neurons with myelin and many neural connections begin to fail.
Many patients can experience a loss of myelin as a result of a demyelinating disease. There are a number of these diseases, including multiple sclerosis, which is the best known and most common. Patients with multiple sclerosis lose myelin as a result of an improper immune response. In this disease, immune cells target and destroy both myelin and the cells that produce it. Patients with this disease may initially have mild symptoms that become progressively worse as more myelin is destroyed.
Inflammation in parts of the central nervous system can also cause a decrease in myelin. The optic nerves, spinal cord, or brain may swell for a number of reasons. When nerves swell, the myelin coating can be damaged. If the patient does not suffer from am autoimmune disease that causes the body to attack or halt production of myelin, the loss of myelin caused by inflammation may be temporary.
There are also inherited conditions that can cause the loss of myelin. Adrenoleukodystrophy and the closely related syndrome, adrenomyeloneuropathy are conditions that interfere with a person’s ability to break down some types of fatty acids. These conditions are linked to a faulty gene on the X chromosome and affects males more often than females. The myelin loss caused by these diseases is severe and irreversible, though there are ways to manage these conditions through diet.