Mood and energy regulation in seasonal and non-seasonal depression before and after midday treatment with physical exercise or bright light

Abstract

The effects of two non-drug treatments (physical exercise and bright light) on mood, body weight and oxygen consumption were compared in age-matched groups of female subjects with winter depression, non-seasonal depression or without depression. It was found that oxygen consumption in the pre-treatment condition was similar in non-depressed subjects (n=18) and depressed non-seasonals (n=18), while comparatively lower values were obtained in winter depression (n=27). Neither mood nor metabolic parameters changed significantly in the group of nine untreated winter depressives. One week of physical exercise (1-h pedaling on a bicycle ergometer between 13.00 and 14.00 h) increased oxygen consumption in the group of nine winter depressives and lowered oxygen consumption in nine-subject groups of depressed and non-depressed non-seasonals. One week of bright light treatment (2-h exposure to 2500 lux between 14.00 and 16.00 h) increased oxygen consumption in nine winter depressives and nine non-depressed subjects, while no significant change in oxygen consumption was found in nine subjects with non-seasonal depression. Weight loss was observed in the groups treated with physical exercise and in the group of light-treated winter depressives. Winter depression responded equally well to exercising and light, while a significant therapeutic difference in favor of exercising was found in non-seasonal depression. Overall, the results of the study suggest that energy-regulating systems are implicated in the antidepressant action of the non-drug treatments.

Introduction

Winter depression, the most common form of seasonal affective disorder (SAD), is a cyclic mood and neuro-vegetative disturbance with regular fall/winter depressions and non-depressed periods in spring/summer (Rosenthal et al., 1984a). This syndrome seems to result mainly from the deprivation of light in wintertime, and patients with SAD benefit from bright light treatment (BLT) within a few days (Rosenthal et al., 1984a). The efficacy of BLT for winter depression has been confirmed by numerous investigators (see Terman et al., 1989, Terman et al., 1998, Wirz-Justice and Anderson, 1990, Wirz-Justice et al., 1993, Lam et al., 1997).

In contrast to winter depression, the clinical effects of light therapy for non-seasonal depression have not been extensively studied. It was concluded that bright light seems to be effective against non-SAD depression (see Lam et al., 1989, Kripke and Gaddy, 1990, Kripke, 1998). However, there were reports of both positive (Kripke et al., 1983, Yamada et al., 1995) and negative findings (Stinson and Thompson, 1990, Mackert et al., 1991).

In normal subjects, the mood-enhancing effect of BLT was reported by several groups (Dietzel et al., 1986, Wirz-Justice et al., 1986, Putilov, 1998). On the other hand, bright light was not found to be beneficial for individuals without a history of winter difficulties (Rosenthal et al., 1987, Kasper et al., 1990, Genhart et al., 1993).

Although the mood-enhancing action of physical activity in healthy and depressed individuals is a repeatedly confirmed finding (Ledwidge, 1980, Morgan et al., 1980, Hughes, 1984, Simons et al., 1985, Martinsen, 1994), little is yet known about the effectiveness of physical exercise treatment (PET) for winter depression. In the pioneer study of Koehler et al. (1993), 50% improvement of mood was reported following 2 weeks of training on a stationary bicycle between 6.00 and 8.00 h. Kurz et al. (1995) reported a 50% reduction on depressive scales in subjects with SAD and a milder (subsyndromal) form of SAD after 12-day aerobic treatment from 07.00 to 8.00 h. In contrast, no mood effect was found in those depressed subjects who just listened to music and read magazines during the same hours. Moreover, a negative mood effect was found in healthy subjects treated with aerobics.

It was suggested that PET works in SAD because of a circadian phase advance (Koehler et al., 1993). In general, the question about the timing of non-pharmacological treatment for SAD is of both practical and theoretical importance. Midday treatment has been proposed as a test of the mechanisms underlying the clinical effect of BLT. In particular, midday light was used to examine two chronobiological explanations: a normalization of the timing of melatonin secretion by extension of day length with morning plus evening BLT (Lewy et al., 1982), and a correction of abnormally phased circadian rhythms with early morning BLT (Lewy and Sack, 1986, Lewy et al., 1987, Lewy et al., 1988). Indeed, these hypotheses suggest only a weak, if any, therapeutic response to bright light in the midday, because such treatment fails to extend day length or reset the abnormally delayed circadian rhythms. It was found, however, that midday BLT still effectively reverses the symptoms of winter depression (Jacobsen et al., 1985, Wehr et al., 1986, Wirz-Justice et al., 1994).

The well-known distinctive features of endogenous and melancholic subtypes of Major Depressive Disorder are anorexia, loss of weight or appetite, hyposomnia or insomnia, early morning awakening, psychomotor agitation, anxiety, etc. (Spitzer et al., 1978, Zimmerman et al., 1989). By contrast, winter depression is often associated with so-called atypical symptoms including hyperphagia, increased appetite, weight gain, carbohydrate craving, hypersomnia, difficulty waking up in the morning, daytime sleepiness, psychomotor retardation, anergia and fatigability (Rosenthal et al., 1984a, Rosenthal and Heffernan, 1986). It is natural to suggest that the pathophysiological changes in energy-regulating systems may account for these traits of energy-conserving behavior in SAD.

More than 70 years ago Lange (1928) hypothesized that disturbances in energy regulation may be at the basis of the pathophysiology of depression. Since that time, only a few studies of energy regulation in SAD and other depressive subtypes have been conducted. No differences in resting metabolic rate between untreated depressed patients and normal individuals were found by Caroff et al. (1981). Fernstrom et al. (1985) demonstrated that successful treatment with antidepressant medications was accompanied by a reduction in the resting metabolic rate in three non-seasonal depressives. Another group (Zach and Ackerman, 1988) reported an increased resting metabolic rate after recovery in patients with major depression, while patients with minor depression had a non-significant decrease.

The results of the first study of resting metabolic rate in SAD were surprising (Gaist et al., 1990). Contrary to prediction, higher than control values of resting metabolic rate were found in depressed SAD patients, and these values were significantly lowered by BLT.

In our previous studies we did not observe significant changes in the resting metabolic rate in SAD patients treated with bright light in the morning or late afternoon. However, this index significantly increased in summer (Putilov, 1997, Putilov, 1999, Putilov and Danilenko, 1999). We also demonstrated that successful BLT was significantly related to an increase in the oxygen consumption rate (Putilov, 1998, Putilov and Danilenko, 1999), a decrease of body weight (Putilov, 1998, Putilov, 1999), an increase of heart rate (Putilov et al., 1991, Neschumova et al., 1994, Schergin et al., 1996) and an increase in respiratory rate (Putilov, 1998, Putilov and Danilenko, 1999). Moreover, among a number of significant physiological effects of BLT, we observed a decrease of body weight (Putilov et al., 1991, Putilov, 1999) and a rise of daytime levels of TSH (Danilenko and Putilov, 1993) and body temperature (Putilov et al., 1991, Danilenko and Putilov, 1994).

To our knowledge, no research has assessed whether BLT in the middle of the day affects energy regulation in seasonal and non-seasonal depression. Furthermore, there has been no study comparing the effects of PET in the middle of the day on mood and energy regulation in subjects with typical and atypical depressive symptoms. Since physical exercise could normalize body metabolism, it is not excluded that PET could, in particular, affect metabolic parameters in depressed subjects with abnormally low or high metabolic rates.

In the present study we examined psychic and metabolic action of midday PET and BLT in asymptomatic subjects and subjects with typical and atypical depressive symptoms.