Aging in nucleus accumbens and its impact on alcohol use disorders

Changes in the Properties of Ethanol-Sensitive Molecular Targets During Maturation and Aging

At present, there is a good understanding of the negative neurobiological impacts that ethanol has on adolescent and adult brains; the effects of this drug on the aging brain, both normal and pathological, are only now starting to emerge. Biomedical research involving the effects of alcohol on aging is limited; however, studies in human subjects show that older adults perform worse in tests assessing working memory, attention, and cognition as compared to younger adults. The neurobiological basis for these effects in the elderly is largely unknown. In the last 30 years, important molecular targets for ethanol actions in the adolescent and adult brain have been identified. Yet, we know very little about whether these targets are still affected by ethanol in the older brain. The brain structure changes during aging, and the targets and their functional characteristics may also change. Thus, one can expect that ethanol will have distinct effects on the brain of an aged organism.This chapter discusses the available data showing how aging influences critical proteins that affect neuronal excitability, nerve conduction, and synaptic transmission and how aging modifies the sensitivity of these proteins to ethanol. The data show limited information on ethanol's effects in the aged brains of mice and rats.

Reorganization of structural connectivity in the brain supports preservation of cognitive ability in healthy aging

The global population is aging rapidly, and a research question of critical importance is why some older adults suffer tremendous cognitive decline while others are mostly spared. Past aging research has shown that older adults with spared cognitive ability have better local short-range information processing while global long-range processing is less efficient. We took this research a step further to investigate whether the underlying structural connections, measured in vivo using diffusion magnetic resonance imaging (dMRI), show a similar shift to support cognitive ability. We analyzed the structural connectivity streamline probability (representing the probability of connection between regions) and nodal efficiency and local efficiency regional graph theory metrics to determine whether age and cognitive ability are related to structural network differences. We found that the relationship between structural connectivity and cognitive ability with age was nuanced, with some differences with age that were associated with poorer cognitive outcomes, but other reorganizations that were associated with spared cognitive ability. These positive changes included strengthened local intrahemispheric connectivity and increased nodal efficiency of the ventral occipital-temporal stream, nucleus accumbens, and hippocampus for older adults, and widespread local efficiency primarily for middle-aged individuals.