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Researchers here discuss what is know of changes that take place with age in cell membranes in the brain, and how they might negatively affect cell function. Like many aspects of aging, connecting these changes to the set of underlying mechanisms that cause aging is a challenging prospect, yet to be accomplished. Everything changes with age, and drawing connections between any two of those changes in order to demonstrate causation is a hard task.
Aging affects the plasma membrane of all the cells of the body, not only its composition and structure but also the function of its different components. Any change in the lipid composition of the cell membranes will impact the function of membrane receptors and the way the cells sense the environment. Numerous studies have shown the existence of significant differences in the relative amounts of the different lipids in tissues of young and old individuals, and this is mainly evident in the brain, because the blood-brain barrier strictly controls the entrance of lipids to the central nervous system. In particular, an increase in saturated fatty acid content and a decrease in polyunsaturated fatty acid (PUFA) content was found with age starting from 50 years old.
Lipid changes in the old seems to be more pronounced in lipid raft fractions of the plasma membrane. Using lipid rafts isolated from human frontal cortex in nondemented subjects aged from 24 to 85 years, researchers showed that these lipid rafts undergo significant alterations of specific lipid classes with aging. Furthermore, lipid rafts seems to be particularly sensitive to aging and decreased arachidonic acid (AA) and docosahexaenoic acid (DHA) levels in lipid rafts may represent an early event during normal aging, at least in the brain. These results clearly show that lipid remodeling occurs at the plasma membrane with aging. In the brain, some of these changes seem to occur early, at the starting point of the aging process, supporting the hypothesis that reshaping of the plasma membrane may be a very early event in the development of cellular aging, responsible for the occurrence of some of the typical manifestations of aging.