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Am J Neurodegener Dis 2013;2(4):228-246

Review Article
Aging, circadian rhythms and depressive disorders: a review

Inês Campos Costa, Hugo Nogueira Carvalho, Lia Fernandes

Faculty of Medicine, University of Porto, Portugal; Psychiatry Service, Centro Hospitalar de São João, Porto, Portugal;
CINTESIS & Faculty of Medicine, University of Porto, Porto, Portugal

Received September 8, 2013; Accepted September 23, 2013; Epub November 29, 2013; Published December 15, 2013

Abstract: Introduction: Aging is typically associated with impairing behavioral patterns that are frequently and
inappropriately seen as normal. Circadian rhythm changes and depressive disorders have been increasingly
proposed as the two main overlapping and interpenetrating changes that take place in older age. This study aims to
review the state of the art on the subject concerning epidemiology, pathophysiological mechanism, clinical findings
and relevance, as well as available treatment options. Materials and Methods: A nonsystematic review of all English
language PubMed articles published between 1995 and December 2012 using the terms “circadian rhythms”, “mood
disorders”, “depression”, “age”, “aging”, “elderly” and “sleep”. Discussion and conclusion: Sleep disorders, mainly
insomnia, and depression have been demonstrated to be highly co-prevalent and mutually precipitating conditions in
the elderly population. There is extensive research on the pathophysiological mechanisms through which age
conditions circadian disruption, being the disruption of the Melatonin system one of the main changes. However,
research linking clearly and unequivocally circadian disruption and mood disorders is still lacking. Nonetheless, there
are consistently described molecular changes on shared genes and also several proposed pathophysiological
models linking depression and sleep disruption, with clinical studies also suggesting a bi-directional relationship
between these pathologies. In spite of this suggested relation, clinical evaluation of these conditions in elderly patients
consistently reveals itself rather complicated due to the frequently co-existing co-morbidities, some of them having
been demonstrated to alter sleep and mood patters. This is the case of strokes, forms of dementia such as Alzheimer
and Parkinson, several neurodegenerative disorders, among others. Although there are to the present no specific
treatment guidelines, available treatment options generally base themselves on the premise that depression and
sleep disturbances share a bidirectional relationship and so, the adoption of measures that address specifically one
of the conditions will reciprocally benefit the other. Treatment options range from Cognitive Behavioral Therapy,
Chronotherapy, and Light therapy, to drugs such as Melatonin/Melatonin agonists, antidepressants and sedatives.

Keywords: Aging, circadian rhythms, depressive disorders, Alzheimer, Parkinson, sleep

Address correspondence to: Lia Fernandes, CINTESIS & Faculty of Medicine, University of Porto, Al, Hernâni Monteiro,
4202-451 Porto, Portugal. E-mail: lfernandes@med.up.pt; Inês Campos Costa or Hugo Nogueira Carvalho, Faculty of
Medicine, University of Porto, Portugal. E-mail: inescamposcostamd@gmail.com (Inês Campos Costa); carvalho.
hn@gmail.com (Hugo Nogueira Carvalho)