1 December 2012
Recently, numerous lifestyle factors have been described that influence the risk of dementia such as smoking, obesity, and physical exercise, or certain nutrients like selenium [1]. Another factor that has received little attention to so far, although it might be of crucial importance in the modern human environment with its increasing complexity and speed-up of daily events, is stress. Psychological stress occurs when individuals face situational demands that exceed their adaptive capacity.
There are different lines of evidence supporting the importance of the role of stress on the development of dementia. Mechanistically, it has long been known that cortisol receptors in the hippocampus might contribute to forgetting. What is adaptive in acutely stressful situations may become a hazard in long-term stress [2, 3].
Observational studies found an association between stressful periods in life and later incidence of Alzheimer’s disease (AD) (see [1] for further references). Stress induces depression and other indications that are associated with AD. Neurophysiological knowledge from stress reducing practices speaks in favor of the importance of the role of stress on AD. While there are no reliable data, to our knowledge, that specifically document the effect of stress reducing practices on the prevention of cognitive decline, research has shown that (a) hippocampal volume is larger in participants with mindfulness training than in age-matched controls, (b) meditation may be used as a method of reducing the activity of the default mode network, whose structures overlap those implicated in AD, and (c) meta-cognitive awareness, a tool to anticipate stress factors before they become ingrained patterns, is developed through meditation. Furthermore, Zen-meditators show no cognitive decline with aged compared with age-matched control [4].
The study of Hebda-Bauer et al. now shows that the HPA axis is activated during early stages of the neuropathology in 3x-Tg AD-mice indicating an increased vulnerability to stress at the initial stages of the disease [5]. Therefore, approaches to reduce stress might not only address a crucial risk factor for AD, but also teach people how to cope with the disease-associated stress, reduce the incidence of other stress-related diseases, and in such a way increase their quality of life.
In reaction to our current culture of information overload, high speed information processing due to high through-put demands, and the promotion of multi-tasking, the awareness and management of daily stresses can be promoted through simple and cost-effective techniques such as meditation, which might provide a practical preventative tool for AD. For those who are spiritually inclined, if regarded under the umbrella of spirituality [6], it might additionally help people to better adhere to a healthy lifestyle [7, 8] and represent essential components in lifestyle-based prevention programs [1].
Future studies are needed to explore the potentials of stress reduction programs in the primary and secondary prevention of dementia.
Martin Loef, Majella Horan, Harald Walach
European University Viadrina, Institute of Transcultural Health Studies, Frankfurt (Oder), Germany; walach@europa-uni.de
References:
[1] Walach H, Loef M (2012) Towards primary prevention of Alzheimer’s disease. Am J Alzheimers Dis 1, 1-28.
[2] van Praag HM, de Kloet R, van Os J (2004) Stress, the Brain, and Depression. Cambridge University Press, Cambridge.
[3] Bremner JD, Narayan M, Anderson ER, Staib LH, Miller HL, Charney DS (2000) Hippocampal volume reduction in major depression. Am J Psychiatry 157, 115-117.
[4] Pagnoni G, Cekic M (2007) Age effects on gray matter volume and attentional perfomance in Zen meditation. Neurobiol Aging 28, 1623-1627.
[5] Hebda-Bauer EK, Simmons TA, Sugg A, Ural E, Stewart JA, Beals JL, Wei Q, Watson SJ, Akil H (2013) 3xTg-AD mice exhibit an activated central stress axis during early-stage pathology. J Alzheimers Dis 33, 407-422.
[6] Walach H (2011) Spiritualität: Warum wir die Aufklärung weiterführen müssen. Drachen Verlag, Klein Jasedow.
[7] Powell LH, Shahabi L, Thoresen CE (2003) Religion and spirituality: linkages to physical health. Am Psychologist 58(1), 36.
[8] Boswell G, Kahana E, Dilworth-Anderson P (2006) Spirituality and healthy lifestyle behaviors: stress counter-balancing effects on the well-being of older adults. J Religion Health 45, 587-602.
