Robert G. Skwerer

Psychobiological effects of carbohydrate- and protein-rich meals in patients with seasonal affective disorder and normal controls

Patients with seasonal affective disorder (SAD) frequently report carbohydrate craving and note that carbohydrate ingestion energizes them. Bright artificial light has been shown to reverse the symptoms of SAD, including carbohydrate craving. In this study, 16 depressed SAD patients and 16 matched controls were fed two different isocaloric meals, one rich in protein and one rich in carbohydrates, in a crossover design. Although their biochemical response in terms of plasma large neutral amino acid concentrations was identical, SAD patients reported activation following carbohydrate ingestion, whereas normal controls reported sedation. Marked ordering effects on psychological parameters were noted, suggesting that order should be taken into account as a methodological consideration in meal studies.

Phototherapy for Seasonal Affective Disorder

is not a new one. Indeed, books were written on the subject in the early decades of this century (Humphris, 1924; Kovacs, 1932). However, there are important distinctions between the treatments outlined in these earlier texts and the phototherapy currently in use. These earlier clinicians regarded phototherapy as a broad-spectrum treatment for a wide variety of ills. Ultraviolet light was considered an important component of the treatments, and the entire body was exposed to the light. The emphasis was thus on exposing the skin to light, and special &dquo;light baths&dquo; were designed to maximize skin exposure and to shield the eyes from toxic ultraviolet rays. In contrast, phototherapy is currently regarded as helpful only with certain specific types of patients; the light sources used have contained relatively little ultraviolet light; and emphasis has been placed on the eyes rather than the skin as the portal of entry of the therapeutic effect. The majority of phototherapy studies conducted in the past few years have involved patients with SAD, a condition characterized by regular winter depressions alternating with nondepressed periods in the spring and summer (Rosenthal et al., 1984). There are a few recorded historical examples of manipulations of lighting and climate specifically aimed at reversing certain winter difficulties such as depression and lethargy. Esquirol (1845) reported a case of a man with symptoms remarkably similar to those of SAD, whom he treated successfully by advising him to move from

Neurobiology of Seasonal Affective Disorder and Phototherapy

I. To whom all correspondence should be addressed, at the Clinical Psychobiology Branch, NIMH. Building 1.0/Room 4S-239, 9000 Rockville Pike, Bethesda. Maryland 20892. The investigation of the biochemical basis of seasonal affective disorder (SAD) and light therapy is a new field. As with any body of knowledge undergoing rapid expansion, the data, though interesting, are incomplete and at times even conflicting. In this paper, we attempt to organize and synthesize the information currently available into a coherent and understandable form.

Effects of light treatment on core body temperature in seasonal affective disorder

Abnormalities in circadian rhythms of core body temperature have been reported previously in depressed patients. In this study, we compared the temperature rhythms of 10 depressed seasonal affective disorder (SAD) patients with winter depression with those of 12 normal controls and evaluated the effects of bright light on temperature in SAD. Unlike previous studies of depressed patients, the temperature curves of the patients and normal controls during the off-light condition were nearly identical. We found a significant difference in amplitude between the patients in the untreated and light-treated conditions. Although there was no systematic difference in circadian phase across groups or treatment conditions, we present preliminary evidence that suggests that phase-typed subgroups may be present in the population distinguished by their treatment responses.

Sleep in fall/winter seasonal affective disorder: effects of light and changing seasons.

Disturbances of sleep are a hallmark of seasonal affective disorders (SAD), as they are of other mood disorders. Fall/winter SAD patients most often report hypersomnia. Among responses of 293 SAD patients on a symptom questionnaire, complaints of winter hypersomnia (80%) greatly exceeded insomnia (10%), hypersomnia plus insomnia (5%), or no sleep difficulty (5%). Increased sleep length in fall/winter is not unique to SAD. Among 1571 individuals across four latitudes surveyed at random from the general population, winter sleep increases of < or = 2 hr/day relative to summer were reported by nearly half. However, hypersomnia had a low correlation (r = 0.29) with the total number of other SAD symptoms that were reported in this sample. Ten SAD patients kept daily sleep logs across 1 yr that showed increases in fall and winter (sleeping most in October; least in May) whose maximum averaged 2.7 hr per day more weekend sleep than in spring and summer. These winter increases might have been somewhat attenuated since most received light therapy during part of the winter. Nocturnal EEG recordings of depressed SAD patients in winter showed decreased sleep efficiency, decreased delta sleep percentage, and increased REM density (but normal REM latency) in comparison with recordings: (1) from themselves in summer; (2) from themselves after > or = 9 days of light therapy; or (3) from age- and gender-matched healthy controls. Thus, the extent of fall/winter oversleeping recorded by our SAD patients did not differ dramatically from that reported by the general population, but sleep complaints of our SAD patients have been accompanied by features of sleep architecture that are different from healthy controls and are reversed by summer or by bright-light therapy.

No mood-altering effects found after treatment of normal subjects with bright light in the morning

Studies have shown that depressed patients with seasonal affective disorder (SAD) respond to treatment with bright artificial light. In this study 2 hours of bright artificial light administered in the morning for 1 week did not alter mood in 11 normal subjects. This finding suggests that the mood-enhancing effect of light for SAD patients is not necessarily generalizable to other populations.

Effects of bright light on resting metabolic rate in patients with seasonal affective disorder and control subjects

Many of the symptoms of seasonal affective disorder (SAD) could be construed as having an energy-conserving function. We predicted that SAD patients would have abnormally low resting metabolic rates (RMR), which would be increased to normal levels by light therapy. To test this hypothesis we measured RMR in 10 patients on and off light treatment and 9 normal controls. Contrary to our prediction we found that SAD patients had significantly higher RMR values compared with the normal population (p less than 0.02) and these values were significantly lowered by light treatment (p less than 0.05). The possible implications of these findings are discussed.

Differential response of rat splenic lymphocytes to short-term and long-term neuroendocrine challenges: possible desensitization of the cellular immune response to corticosteroids

The effects of acute or chronic in vivo or in vitro exposures to supra-physiologic doses of isoproterenol, insulin or dexamethasone on rat splenic lymphocyte proliferation were investigated. Acutely, all in vivo challenges inhibited mitogen-induced lymphocyte proliferation, and correlated to increased corticosterone levels. However, chronic in vivo exposure to dexamethasone resulted in lymphocyte activity which was equivalent to controls, while chronic isoproterenol treatment enhanced the lymphocyte response to mitogen. These data suggest that chronic stress may result in a desensitization of the immune system to corticosteroids as well as a direct in vivo modulation by isoproterenol to enhance lymphocyte proliferation.