EFECTOS COGNITIVOS Y EMOCIONALES DEL ENVEJECIMIENTO: APORTES DE INVESTIGACIONES BASICAS PARA LAS ESTRATEGIAS DE REHABILITACION.

The aging process is a universal phenomenon that affects all kinds of life. It is associated to a general impairment of physiological functions. Among these functions we are interested in brain functioning, that is linked to behavioral, cognitive, and emotional problems. In the present article, results related to aging are presented, within the fields of cognition and emotion, with special emphasis in animal models. Though it could be quite artificial to separate cognitive from emotional functions because they interact with each other, in the present review article, we present behavioral and neurophysiological studies, in which the changes that aging process has upon the already mentioned functions have been considered. Lastly, we mention the treatments used to deal with these aging-related psychological problems. On one hand, within the cognitive functioning, one of the most evident impairments in humans is related with evocation memory, that is, the inability to recall information. Working memory is also compromised, specially when people face tasks that require complex parallel processing. On the other hand, procedural memory is usually conserved. Animal models have also shown that spatial long-term memory and spatial working memory are impaired with aging. In addition, executive functions are affected as evidenced by an impairment in attention, discrimination, and analysis of complex information in animals. The processing of reward incentive shifts is altered, as shown by the persistence of previously learned responses in aging rats. The temporal lobe and the prefrontal cortex seem to be the most important brain regions involved in this deficit. Cholinergic hypofunction may be the start point of these cognitive problems, also probably linked with an affected GABAergic transmission. Considering the emotional functions, aging humans may show anhedonia and a deficient gesture recognition associated with emotional states. In human and non-human studies, an exaggerated response to stress situations has been found, which is probably related to elevated noradrenaline levels, and to a dyisregulation of the HPA negative feedback. These findings, taken together, have allowed applied scientists to develop therapeutic goals. First, the existence of a set of drugs that enhance cholinergic functioning, and that have been successfully tested in non-human animal studies. Besides, diverse animal studies have tested drugs that modulate 5TH-ergic neurotransmission, and vaso-dilating drugs also seem to have a beneficial effect upon the performance on memory tasks. Second, on a cognitive-behavioral level, a preventive and healing effect of cognitive exercising has been proven. This has lead to the development of cognitive stimulation programs directed to third-age people, with the goal of reducing the aging impact, and the associated mental illnesses, such as Alzheimer. Behavioral interventions in humans also include maintaining and caring for general health, and adequate feeding, physical exercise, and specific cognitive training. Studies with non-human subjects are showing the positive impact that the exposure to an enriched environment has on neuronal plasticity, which also implies enhancing cognitive functioning. Hebb (1949) already insisted on neuronal plasticity as a function of use, which eventually has been confirmed on recent research. In our concern, the use means that one of the crucial factors to reach a satisfactory aging process is to prompt an adequate interaction between the elderly and their environments, which may also mean to provide physical, social, and mental activities to deal with the environmental impoverishment that could arrive in the last period of our lives. [ABSTRACT FROM AUTHOR]