MODULE SUPPLEMENT: NEUROLOGICAL SYSTEM
Central Neurotransmitters and Aging

There are numerous putative neurotransmitters within the nervous system. These include the Monamines which are comprised of the catacholamines (norepinephrine, dopamine) and the indoleethyline, 5-hydroxytryptamine (serotonin), as well as acethylcholine. Others include various peptids and amino acids such as GABA and glycine. Alterations in the levels of various neurotransmitters or their receptors have been studied extensively, but much of this research has been accomplished in animals and many of the findings are conflicting. As noted earlier, data support changes in both norepinephrine and dopamine which may impact gait and balance as well as cognitive functioning. Changes in acetylcholine (ACH) in Alzheimer's disease underpins the use of cholinergic drugs such as Tacrine (Cognex), Rivastigmine (Exelon), and Galantamine (Reminyl) each of which increases ACH levels, although in slightly different ways.

However, what may be KEY in terms of clinical findings is the imbalance that changes in the various neurotransmitters can create in the regulation of normal physiologic functioning.

An example is Parkinson's disease where there is a significant loss of dopamine. This off sets the balance that is usually present among the various neurotransmitters that facilitate or inhibit movement--especially GABA and acetycholine. But similar dysregulation can occur in other systems.

Increasingly, a range of neurotransmitters are found to be involved in various aspects of cognitive functioning, and changes in their levels, neurons, or synapses can result in problems related to maintaining the smooth interconnected functioning of the nervous system. Neurotransmitters and aging is an area of current research.

Indiana State's biochemistry department posts information on known neurotransmitters on their site at Biochemistry of Neurotransmitters. This site provides interesting information on neurotransmitters. As more material becomes available it will be added into text. If you find a site that is of interest and you feel is content correct, please let us know.