Normal aging in the nervous system: implications for SCI nurses.

The normal microscopic and macroscopic changes that occur with aging and the neurophysiological effects of these neuroanatomical changes are described. Among the microscopic changes are dendritic and neuronal losses, thinning of axons and myelin sheaths; a decrease in the number of receptors and amount of neurotransmitter available together with the appearance of lipofuscin, granulovacuolar organelles, neurofibrillary tangles and senile plaques. Macroscopic changes include decreases in the weight and volume of the brain, thinning of the cortical mantle and white matter tracts, widening of sulci and fissures, and meningeal thickening. Neurophysiologically aging persons evidence decreased recent memory, a decreased ability to process information and an increased conduction time. These factors result in increased learning time, response time and, hence, recovery time. The major nursing implications of these neurophysiological changes for spinal cord injured persons relate to safety when mobilizing and engaging in self care and providing increased learning time.