Memory Loss Due to Brain Demylenating Lesions

The central nervous system is composed of millions of nerve cells (neurons) and other tissues which control the body's every function. Like with any other body system, there are diseases and conditions which have an effect on the central nervous system's ability to perform its function. One of those functions is memory, and anything that interferes with the central nervous system may also have a detrimental effect on memory.

Neurons

• Neurons are the main cells of the central and peripheral nervous systems. In both systems, neurons carry electrical impulses from one part of the body to another. These electrical impulses are the messages that make muscles move, the heart beat, and memories be stored in the brain. Like with electrical wiring in a home, an insulator is needed to keep the impulses flowing the right way. Myelin is a protein that acts as an insulator around neurons.

Memory

• Memories are stored in neurons in the brain as chemical and electrical impulses. The exact mechanism of how memory works is not completely understood, but the mechanisms by which memory can be damaged are. It has been noted through anecdotal and experimental data that trauma to the brain cells causes memory loss. If the trauma demyelinates (strips away myelin from) the neurons, the electrical impulses used for memory storage misfire and the nerves and memories are lost.

Demylenating Conditions

• There are several known demyelinating conditions. Lou Gehrig's disease is one of them, yet it affects mostly the myelin in the muscle neurons of the body, not so much the brain. According to the Mayo Clinic, Multiple Sclerosis is the most common demyelinating disease. In it, the body's own immune system attacks and destroys myelin, leaving behind scar tissue and the resulting nerve impulse misfiring. A similar, yet not well understood mechanism happens with Alzheimer's Disease. Simple mechanical trauma like that suffered during a concussion also damages myelin and may also lead to memory loss and mobility problems.

Memory Loss

• As the myelin is stripped from neurons in the brain that help with memory, the electrical impulses received from the senses are corrupted, leading to memory loss or the inability to form new memories. Short-term memory loss is when the individual cannot make new memories or remember things just learned. People with short-term memory loss cannot make new acquaintances, yet they retain the knowledge of who they are as well as other details from years past. Long-term memory loss leads to the loss of memories from years past, where the individual forgets who they are, their name, or even how to perform simple tasks.

Other Neurological Conditions

• There are other neurological conditions which may lead to memory loss without loss of the myelin around neurons. These include psychogenic conditions where the disease is of the mind and not the physical function of the brain. Some medications, like sedatives and anti-psychotics, also have an effect on memory. Infections of the brain (encephalitis) or their surrounding tissues (meningitis) can also damage memory neurons or even kill them.