More Evidence to Reinforce "Use It or Lose It," Even in Later Life
Most older people exercise the body and mind far less than they should; as a consequence some degree of the frailty observed in old age in wealthier parts of the world is preventable, a case of neglect rather than unavoidable outcome. You can't choose not to age, yet, but you can choose to exert yourself in order to make matters better than they would otherwise be. There are plenty of studies to show that, even in very late life, greater levels of mental and physical activity produce benefits. In this paper, the researchers dig deeper to see if certain forms of activity can be tied to specific benefits in cognitive function and physiology, but given the current poor state of health maintenance in the general population, I think it more important as yet another set of evidence to show that "use it or lose it" is very real.
The human hippocampus (HC) is affected not only by pathological aging such as in Alzheimer's disease but also by the normal aging process resulting in deficits in memory, learning, and spatial navigation at old age. Magnetic resonance-studies indicate an atrophy rate of the hippocampus and the nearby parahippocampal gyrus of 2-3% per decade, which is further accelerated in the very old age where there is an annual loss of 1% over the age of 70. On the other hand more recent research has shown that the HC counts among the few brain regions with the ability to generate new neurons throughout the lifespan.
In animal models physical activity has been identified as a key mechanism that can drive this adult neuroplasticity. In humans, research has focused on the effects of aerobic fitness and training on volumes and perfusion of the HC. Results reveal that higher cardiorespiratory fitness levels (VO2 max) are associated with larger hippocampal volumes in late adulthood, and that larger hippocampal volumes may, in turn, contribute to better memory function. Furthermore, some investigations also assessed possible physiological mediators of the observed neuroplasticity, such as brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF). However, the role of cardio-respiratory fitness in modulating hippocampal gray matter volume is still under debate.
The hippocampus is also involved in spatial navigation and in motor sequence consolidation suggesting that motor skill learning and motor fitness can have impact on hippocampal volume without any cardio-respiratory change. Hence, the HC seems not only crucial for long-term memory consolidation, learning and spatial navigation, but also for balancing. Intact balance is essential for social mobility and quality of life in aging. Hence, physical intervention programs should take this function into account, too.
In this respect dancing seems to be a promising intervention since it requires the integration of sensory information from multiple channels (auditory, vestibular, visual, somatosensory) and the fine-grained motor control of the whole body. Behavioral studies have already provided evidence of better performance in balance and memory tasks in elderly dancers, but the underlying neural mechanisms have not been addressed comprehensively so far. Knowing that aerobic, sensorimotor and cognitive training contribute to hippocampal volume, which also seems to be associated with balancing capabilities, we initialized a prospective, randomized longitudinal trial over a period of 18 months in healthy seniors. Two interventions were compared: a specially designed dance program, during which subjects constantly had to learn new choreographies, and a traditional fitness program with mainly repetitive exercises.
Before and after intervention, balance was evaluated using the Sensory Organization Test and HC volumes were derived from magnetic resonance images. Fourteen members of the dance (67.21 ± 3.78 years, seven females), and 12 members of the fitness group (68.67 ± 2.57 years, five females) completed the whole study. Both groups revealed hippocampal volume increases mainly in the left HC (CA1, CA2, subiculum). The dancers showed additional increases in the left dentate gyrus and the right subiculum. Moreover, only the dancers achieved a significant increase in the balance composite score. Hence, dancing constitutes a promising candidate in counteracting the age-related decline in physical and mental abilities.