Bright light therapy in the treatment of childhood

Authors: Krzysztof Krysta Marek Krzystanek Małgorzata JanasKozik Irena KrupkaMatuszczyk

Publish Date: 2012/07/19

Volume: 119, Issue: 10, Pages: 1167-1172

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Abstract

Circadian rhythm disorders represent an important component underlying the pathology of depression One of the subtypes of depression in which these disorders may play a crucial role is the seasonal affective disorder SAD The bright light therapy BLT has been reported as a novel promising treatment method for SAD since 1984 and most of the data revealing its efficacy has been referred to adult patients without comorbid disorders However in the recent years more and more reports have been presented which confirm the usefulness of BLT in some specific subpopulations of patients including children adolescents and pregnant women The present review summarizes the applications of BLT in antepartum depression childhood and adolescence depression as well as in patients suffering from eating disorders Although the body of evidence is still too small to recommend the use of BLT as the first line of treatment for the depression or eating disorders in these patient subpopulations it appears that BLT may be a useful alternative or adjunctive therapy for these diseases However the specific clinical applications of BLT in these areas need further investigationA possible connection between the psychopathology of depressive disorders and circadian rhythms has been postulated for many years however the underlying biological mechanisms still remain unexplained There are some data suggesting that the effect of antidepressive medications is at least partially due to their action on the circadian rhythms McClung 2007 Exploring of the neurobiological mechanisms has contributed to the discovery of socalled clock genes which are present in many cells of the central nervous system and which are responsible for the circadian rhythm abnormalities leading to disrupted behavioral states Turek 2007 These biological connections may explain how close are the relations between sleep disorders and depressive symptoms According to Harvey 2011 sleep disturbances are important but still underrecognized mechanisms related to the etiology and clinical course of mood disorders In particular abnormal sleep patterns may be risk factors for the relapse of depressive episodes as well as for the deterioration of cognitive and emotional regulation and hormonal or metabolic disordersAccording to Antonijevic 2008 there may be different subtypes of depression due to some alterations in functioning of the hypothalamic–pituitary–adrenal HPA axis and different patterns of sleep architecture This kind of distinction may serve as a future marker potentially helpful in the selection of individually targeted treatment strategies One of the first subtypes of depression in which the positive effects of bright light therapy BLT were observed was the seasonal affective disorder SAD Rosenthal et al 1984 reported the first attempt of using BLT in a group of 29 patients who were diagnosed with the bipolar disorder Since that time a number of studies analyzing the efficacy of BLT have been published The mechanism of BLT is complex and different explanations have been proposed including the circadian rhythm hypothesis based on the sleep phase shift This might mean that the individuals suffering from SAD during the winter might have the sleep phase delayed or advanced in relation to their sleep/wake cycle Lewy et al 2007 It is assumed that BLT applied in the morning reduces the secretion of melatonin in phaseshift delay Depending on the individual circadian rhythm changes the morning or evening BLT application could be indicated as adjunctive chronobiological treatment methods for SADOne of the most important anatomical structures responsible for mood control is the suprachiasmatic nucleus SCN which is considered to be the circadian pacemaker of many different physiological and behavioral processes Arushanian and Popov 2011 The neuronal activity of SCN is regulated by two Gprotein coupled melatonin receptors MT1 and MT2 and by melatonin secretion from the pineal gland SCN receives neuronal impulses from the retina via the retinohypothalamic tract Dubocovich 2007 Therefore the level of melatonin secretion depends on the exposure to light during the day time and also on the season of the year The exact way of the SCN regulation still remains hypothetical One possibility is that the indolamines melatonin and its precursor serotonin have an ability to transduce light signals into the SCN Another explanation is that the serotonin may play some role in the modulation of SCN networks and in melatonin production by the pineal gland that influences biological rhythmsMoreover it has been hypothesized that the light exerts neurotrophic influence on neurons and thus a prolonged light deprivation can cause functional impairments of the noradrenergiclocus coeruleus system In their experimental work Gonzalez and AstonJones 2008 showed that the permanent light deprivation in rats increased apoptosis in the locus coeruleus however this effect can be reversed by some antidepressant drugsAlso there are some studies suggesting that the mechanism of antidepressant effect of BLT is connected with the functional augmentation of serotonergic and noradrenergic network systems As an illustration a tryptophanfree diet and an administration of the hydroxylase inhibitor alphamethylparatyrosine produce a robust increase of the depressive symptoms in patients diagnosed with SAD while BLT administration remits these symptoms Neumeister et al 1998 It can be considered that the action of BLT is related to the augmentation of serotoninergic and noradrenergic transmission systems In a study by Stastny et al 2003 the serotoninergic and noradrenergic depletions in patients with SAD who were in remission after receiving BLT produced a transient reduction in plasma interleukine 4 levels This may suggest that the BLT may influence the immune system regulation which is often distorted in depressionIn addition the alterations in neurohormones such as ghrelin and leptin may be involved in the pathophysiology of SAD This can result in hyperphagia with cravings for carbohydrates and subsequently can contribute to a moderate weight gain that frequently accompanies depressive and obsessive–compulsive disorders which might favorably respond to BLT Cizza et al 2005 Garaulet et al 2011According to the clinical observations by PraschakRieder and Willeit 2003 the morning BLT may be superior to the evening one since it reduces the secretion of melatonin in phaseshift delay The duration and frequency of BLT exposure are still controversial KronfeldSchor and Einat 2012 For instance Reeves et al 2012 reported that a significant improvement in the depression scores can be found even after a single BLT session

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