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Alcohol abuse by elderly persons may be overlooked by clinicians because the effects of alcoholism on intellectual processes may be attributed to advancing age. In older patients, in whom liver and other organ functions may be reduced, even modest social drinking will impair cognitive abilities. Alcoholism is especially detrimental to older persons because 1) their blood levels of ethanol are higher than those in younger persons, and brain neurons may be more sensitive to the drug; 2) ethanol can disturb their sleep and sexual performance; 3) their cognitive functions may be significantly impaired by ethanol; and 4) for elderly patients, who commonly take a variety of drugs, ethanol and drug interactions are particularly hazardous.

ABSTRACT: The characteristic morphologic changes frequently observed in the brain of an old adult include a decrease in weight and volume, a change in the pattern of cerebral cortical convolutions, and an increase in ventricular size. Cell loss varies from region to region in the brain, and may be intensified in Alzheimer's disease and other disorders associated with senile dementia. Among the neuroglial cells, the microglia undergo the most significant changes with age. Although senile brain disease previously has been regarded as secondary to atherosclerosis, recent neuropathologic studies indicate that only 30 to 40 percent of senile brain disease arises from cerebrovascular pathologic lesions. The dilemma remains, however, of how much of the deterioration observed in the aged is related to disease and how much to senescence. The interaction between gene expression and environmental conditions in aging is another important question for the geriatrician. Progress in the control and treatment of disorders associated with old age depends upon further research into the mechanisms that underlie the process of aging in the brain.

Developing Long-Evans rats were undernourished to produce a body-weight deficit of 39% at the age of weaning. Well-nourished litter mates were used as controls. Morphometric analyses were made of pyramidal tracts and posterior tibial nerves of each animal. In measuring pyramidal tract, we observed that axonal circumferences of myelinated fibers were smaller in the undernourished rats and that the number of myelin lamellae per axon appeared reduced by a small amount. The most striking observation in the undernourished rats compared to the controls was that the proportion of myelinated fibers was decreased by 40% at 20 days of age. Axon circumferences of nonmyelinated axons were not measured. Similar decreases were observed in myelinated axon circumference and myelin lamellae of posterior tibial nerves of undernourished rats. Because of sampling problems, we did not attempt to compare the proportion of myelinated and nonmyelinated fibers in posterior tibial nerves of undernourished and well-nourished rats. These morphometric data, particularly the reduction of myelinated fibers, are consistent with biochemical studies of brain hypomyelination in undernourished rats. The data indicate that the mechanism of hypomyelination in nutritionally deprived rats involves a failure of the “trigger” by which myelin-forming cells being to sheath axons in myelin.

Available evidence suggests that age is an important determinant of the levels of neurotransmitters and their associated enzymes and metabolites in some regions of the brain. Alterations at the synaptic level, or selective cell death in the brain, or both, may be implicated in progressive loss of function, behavioral changes and the onset of age‐related diseases. Stimulation of hypothalamic neuroendocrine transducer cells by agents that alter neurotransmitter metabolism might provide some measure of control of the process of aging.

Studies of the rapid penetration of intravascular tritium labelled norepinephrine into mouse brain are described. The most intense localization of norepinephrine is seen in the median eminence of the hypothalamus, and this is discussed in terms of the mechanism of stress activation of ACTH release. Autoradiographs showing localization of norepinephrine in the hypophysis, hypothalamus, pineal, choroid plexus, and blood vessels are also shown.

Prolonged exposure of the brain, such as occurs during neurosurgical procedures, frequently results in cerebral swelling and cerebral edema. These changes are generally attributed to disturbances in the cerebral circulation (Cannon1; Obrador and Pi-Suñer2; Evans and Scheinker,3 and Prados, Strowger, and Feindel4,5). Some investigators have been concerned with the permeability of the "blood-brain barrier" in these conditions. By injecting trypan blue intravitally, Prados et al.4,5 found macroscopically visible staining after exposure of the brain, particularly noticeable in the gray matter of the exposed areas. These experiments showed that cerebral vessels undergo an increase in permeability to trypan blue when the brain is exposed to air. In contrast to these observations, Apfelbach,6 Bonvallet and Le Beau,7 and Obrador and Pi-Suñer2 failed to observe such an increase in trypanblue permeability in their experiments on cerebral edema resulting from exposure or from other experimental procedures.

INTRODUCTION In recent years, many theories and a vast amount of empirical data concerning vision have come from various scientific disciplines ranging from electron microscopy, photochemistry, physiology, and ophthalmology to experimental psychology. However, this vast amount of information on vision has been obtained almost exclusively from research on adult subjects. The experimental literature on the postnatal structural and functional development of the visual system in newborn primates is still very fragmentary even though it is generally accepted that high visual acuity must play a basic role in the development of visually-guided behavior of man and the diurnal subhuman primates. Since a number of visual reflexes can be elicited by light at birth or shortly after in newborn primate infants, it is commonly accepted that gross visual sensitivity to light is present at birth. However, in view of the methodologic difficulties in testing neonatal infants and the consequent lack of experimental