Effect of imipramine on the circadian rhythm of plasma melatonin in unipolar depression

Antidepressants and Circadian Rhythm: Exploring Their Bidirectional Interaction for the Treatment of Depression

Scientific evidence that circadian rhythms affect pharmacokinetics and pharmacodynamics has highlighted the importance of drug dosing-time. Circadian oscillations alter drug absorption, distribution, metabolism, and excretion (ADME) as well as intracellular signaling systems, target molecules (e.g., receptors, transporters, and enzymes), and gene transcription. Although several antidepressant drugs are clinically available, less than 50% of depressed patients respond to first-line pharmacological treatments. Chronotherapeutic approaches to enhance the effectiveness of antidepressants are not completely known. Even so, experimental results found until this day suggest a positive influence of drug dosing-time on the efficacy of depression therapy. On the other hand, antidepressants have also demonstrated to modulate circadian rhythmicity and sleep-wake cycles. This review aims to evidence the potential of chronotherapy to improve the efficacy and/or safety of antidepressants. It includes pre-clinical and clinical studies that demonstrate the relevance of determining the most appropriate time of administration for antidepressant drugs. In parallel, their positive influence on the resynchronization of disrupted circadian rhythms is also herein discussed. It is expected that this review will promote the investigation of chronotherapy for the treatment of depression, contribute to a better understanding of the relationship between antidepressants and circadian rhythms, and consequently promote the development of new therapeutics.

Assessing the Dim Light Melatonin Onset in Adults with Autism Spectrum Disorder and No Comorbid Intellectual Disability

This study assessed melatonin levels and the dim light melatonin onset (DLMO) in adults with Autism Spectrum Disorder (ASD) and also investigated the relationships between melatonin and objectively measured sleep parameters. Sixteen adults with ASD (ASD-Only), 12 adults with ASD medicated for comorbid diagnoses of anxiety and/or depression (ASD-Med) and 32 controls participated in the study. Although, the timing of the DLMO did not differ between the two groups, advances and delays of the melatonin rhythm were observed in individual profiles. Overall mean melatonin levels were lower in the ASD-Med group compared to the two other groups. Lastly, greater increases in melatonin in the hour prior to sleep were associated with greater sleep efficiency in the ASD groups.

Effect of antidepressants on melatonin metabolite in depressed patients

Antidepressants increase melatonin levels, but it is still unclear whether this effect is related to the improvement of depressive symptoms or to unrelated pharmacological action of antidepressants. To answer this question, the effect of antidepressants on 6-sulphatoxymelatonin (aMT6s), the main melatonin urinary metabolite, was examined in drug-free depressed patients - most of them antidepressant-naive. aMT6s was evaluated in 34 depressed patients, before and after 8 weeks of placebo (n = 12) or antidepressant (n = 22; fluoxetine, duloxetine or Hypericum perforatum). Both groups showed an improvement of depressive symptoms after treatment compared to baseline (Hamilton Depression scores): 17.0 +/- 1.4 vs. 9.0 +/- 2.8, P = 0.007 for placebo, and 18.6 +/- 1.1 vs. 11.8 +/- 1.6, P < 0.001 for antidepressants). After treatment, aMT6s levels increased after antidepressants (P < 0.01), but not after placebo (P > 0.05). As depressive symptoms improved both in patients taking antidepressant and in those taking placebo, but an effect of antidepressants could only be seen in those taking antidepressants, we suggest that melatonin changes after antidepressants are more likely due to a pharmacological action of these drugs on melatonin secretion.

Circadian rhythm of parasuicide in relation to violence of method and concomitant mental disorder

Circadian occurrence of parasuicide was evaluated in relation to sex, violence of parasuicide method and psychiatric diagnosis. In all, 457 consecutive episodes of parasuicide were recruited during a 5-year period. Complete data for time of parasuicide, parasuicide method, parasuicide recurrency and psychiatric diagnosis (ICD-9) were available for 304 subjects. Parasuicide methods were classified into two groups depending on the violence of the method. Parasuicide occurred significantly more often in the afternoon and evening hours for both men and women, for both violent and non-violent methods, both in first-even cases and repeaters, and in the following diagnostic groups: organic mental and psychoactive substance disorders, neurotic disorders and personality disorders. The data support the hypothesis of a circadian rhythmicity of parasuicide, showing an area of chronobiological risk in the afternoon and early evening hours.

Circadian rhythms and the pharmacology of affective illness

The chronic effects of antidepressant drugs (ADs) on circadian rhythms of behavior, physiology and endocrinology are reviewed. The timekeeping properties of several classes of ADs, including tricyclic antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, serotonin agonists and antagonists, benzodiazepines, and melatonin are reviewed. Pharmacological effects on the circadian amplitude and phase, as well as effects on day-night measurements of motor activity, sleep-wake, body temperature (Tb), 3-methoxy-4-hydroxyphenylglycol, cortisol, thyroid hormone, prolactin, growth hormone and melatonin are examined. ADs often lower nocturnal Tb and affect the homeostatic regulation of sleep. ADs often advance the timing and decrease the amount of slow wave sleep, reduce rapid eye movement sleep and increase or decrease arousal. Together, AD effects on nocturnal Tb and sleep may be related to their therapeutic properties. ADs sometimes delay nocturnal cortisol timing and increase nocturnal melatonin, thyroid hormone and prolactin levels; these effects often vary with diagnosis, and clinical state. The effects of ADs on the coupling of the central circadian pacemaker to photic and nonphotic zeitgebers are discussed.

Clinical and chronobiological effects of light therapy on nonseasonal affective disorders

Light therapy (bright or dim light) was given at different times (morning or evening) to 27 unmedicated patients with nonseasonal depression (according to DSM-III-R criteria) and 16 normal volunteers. Circadian rhythms in body temperature were measured before and after light therapy. Bright light significantly improved clinical symptoms of depression, as measured by the Hamilton Rating Scale for Depression (HRSD), independent of the time of phototherapy. Dim light therapy had no effect on HRSD scores. Circadian rhythms of body temperatures in patients with affective disorder were more sensitive to the entraining effects of bright light than those of normal subjects, but these effects were not related to clinical improvement. Bright light exposure has an antidepressant effect on patients with nonseasonal depression, but the effect is unlikely to be mediated via the same circadian system that regulates body temperature.

Circadian rhythm abnormalities of deep body temperature in depressive disorders

We investigated circadian rhythms of body temperature in 62 inpatients with major depressive episodes, by monitoring the deep body temperature through the abdominal skin every two hours for a consecutive 48-h period. The data were analyzed by both the least-squares method and the maximum entropy spectral analysis (MEM) and were compared with those in 29 normal volunteers who apparently had a regular 24-h sleep-wake schedule. Circadian rhythm phase disturbances in the depressed patients were likely to be manifested in a phase normal or a phase delay pattern rather than in a phase advance pattern. The amplitude of body temperature was significantly smaller and the mesor was higher in the depressed patients than in the normal subjects. Analysis by MEM revealed that the periods of circadian rhythm of body temperature tended to be longer in the depressed patients than in the normal subjects, though there was no significant difference. The power spectral density by MEM was significantly lower, and there were significantly more ultradian rhythm components in the depressed patients than in the normal subjects. These findings suggest that the fundamental rhythm disturbance in depression may be a weakening of the coupling processes between internal pacemakers and an abnormal sensitivity to environmental information.

Circadian rhythms in depression. Part II: Circadian rhythms in inpatients with various mental disorders

We investigated longitudinally the circadian body temperature rhythms in 65 inpatients with various mental disorders, 38 of whom had major depressive episodes, by estimating the deep body temperature from the skin surface every 2 h for a consecutive 48-h period. To estimate the circadian rhythm, the data obtained were analyzed by the least-squares method and maximum entropy spectral analysis (MEM). Circadian rhythm disturbances in patients with depression were likely to be manifested in phase variability rather than in phase advance. The amplitude of body temperature of the depressed group was significantly less than that of the control group. A positive correlation between the mesor and the severity of the depressive symptoms was found. Moreover, the body temperature of the patients with affective disorders, both in the depressive and in the manic state, tended to fluctuate so much as not only to fit poorly to sinusoid curves, but also to reduce the periodicity of the circadian rhythm. On the basis of these findings, we conclude that the essential feature of the rhythm disturbances in affective disorders is not the phase shift but the instability of the circadian temperature rhythm.