http://journal.frontiersin.org/Journal/10.3389/fnagi.2014.00170/full?
- 1Jacobs Center on Lifelong Learning and Institutional Development, Jacobs University Bremen, Bremen, Germany
- 2AgeAct Research Center, Jacobs University Bremen, Bremen, Germany
Introduction
It has repeatedly been shown that physical activity is positively related to brain structure and function (see Kramer et al., 2006; Hillman et al., 2008; Park and Reuter-Lorenz, 2009) as well as cognitive performance (for a review see Etnier et al., 2006) and that it might reduce the risk of developing dementia (Sumic et al., 2007; Erickson et al., 2012).
Particularly the hippocampal formation has been in the focus of these
studies investigating the positive effect of physical activity on brain
volume because this brain structure is thought to be significantly
involved in diseases related to memory impairment like, e.g.,
Alzheimer’s disease (Driscoll et al., 2003; Barnes et al., 2009).
Whereas positive correlations between cardiovascular activity and
hippocampal volume have been shown, it is unknown whether this applies
to other types of physical activity like, e.g., coordination training,
as well. With this paper we aim to extend the knowledge about the
effects of different physical activity interventions in older adults and
its potential to diminish the decline in hippocampal volume during the
aging process.
The Hippocampus and its Shrinkage Across the Adult Lifespan
The hippocampal formation as part of the limbic system is
located in the medial temporal lobe. It is highly involved in processes
of episodic memory formation (Tulving and Markowitsch, 1998; Van Petten, 2004) and spatial navigation (O’Keefe, 1990; Maguire et al., 2000). Both cognitive dimensions are especially vulnerable to performance loss in late adulthood (cf. Hedden and Gabrieli, 2004). Recently, the hippocampus has also been associated with motor sequence consolidation (Albouy et al., 2008).
Over the adult lifespan, on average, hippocampal volume shrinks about
0.86% per year, but this development is highly non-linear (Raz et al., 2004b).
Whereas for adults below the age of 50 annual hippocampal volume
reductions of only 0.51% were observed, adults above the age of 50
revealed a much steeper annual volume decline of 1.18% (Raz et al., 2004b).
These volume reductions are mainly attributed to reductions in the
neuropil part of the brain structure and – to a smaller extend – to cell
body shrinkage and changes in vascularization (Thomas et al., 2012).
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