Rhythm and blues. Neurochemical, neuropharmacological and neuropsychological implications of a hypothesis of circadian rhythm dysfunction in the affective disorders

Adrift in time: the subjective experience of circadian challenge during COVID-19 amongst people with mood disorders

Social distancing/lockdown policies during the coronavirus (COVID-19) pandemic may alter social rhythms of people through imposition of restrictions on normal daily activities. This may in turn challenge circadian function, particularly in people with mood disorders. Although objective data describing the relationship between circadian disturbances and mood disorders exist, data regarding the subjective experience of circadian challenge is sparse, and its association with mood symptoms is unclear. The present qualitative study was one component of a mixed-methods multi-national project, which took advantage of widespread disruption to daily routines due to Government COVID-related lockdowns during 2020. The Behavior Emotion and Timing during COVID-19 (BEATCOVID) survey study included three open questions generating qualitative data on participants' subjective experience of social disruption due to social distancing/lockdown policies, two of which asked about the barriers and opportunities for stabilizing routines. Responses were coded and analyzed using Thematic Analysis. A total of N = 997 participants responded to at least one of the free-text questions. Four themes were identified: 1) loss of daily timed activities, 2) role of social interaction, 3) altered time perception and 4) disruption to motivation and associated psychological effects. Themes were organized into a provisional heuristic map, generating hypotheses for future research centered on the new concept of 'psychological drift.'

Disrupted rhythms of life, work and entertainment and their associations with psychological impacts under the stress of the COVID-19 pandemic: A survey in 5854 Chinese people with different sociodemographic backgrounds

BACKGROUND & AIM

The coronavirus disease 2019 (COVID-19) pandemic has affected the life and work of people worldwide. The present study aimed to evaluate the rhythm disruptions of life, work, and entertainment, and their associations with the psychological impacts during the initial phase of the COVID-19 pandemic.

METHOD

A cross-sectional study was conducted from the 10th to 17th March 2020 in China. A structured e-questionnaire containing general information, the Chinese version of Brief Social Rhythm Scale, and Zung's self-rating scales of depression and anxiety (SDS and SAS) was posted and collected online through a public media (i.e. EQxiu online questionnaire platform). Scores in sleeping, getting up, and socializing (SGS) rhythm and eating, physical practice, and entertainment (EPE) rhythm were compared among and between participants with different sociodemographic backgrounds including gender, age, education, current occupation, annual income, health status, and chronic disease status. Correlations of SDS and SAS with SGS-scale and EPE-scale were also analyzed.

RESULTS

Overall, 5854 participants were included. There were significant differences in the scores of SGS-scale and EPE-scale among people with different sociodemographic backgrounds. The scores were significantly higher in the groups with female gender, low education level, lower or higher than average income, poor health status, ages of 26-30 years or older than 61 years, nurses and subjects with divorce or widow status. There were also significant differences in SAS and SDS scores among people with different sociodemographic backgrounds (all P< 0.05). The overall prevalence of depression and anxiety was 24.3% and 12.6%, respectively, with nurses having the highest rates of depression (32.94%) and anxiety (18.98%) among the different occupational groups. SGS-scale was moderately correlated with SDS and SAS, and disruption of SGS rhythm was an independent risk factor for depression and anxiety.

CONCLUSION

Social rhythm disruption was independently associated with depression and anxiety. Interventions should be applied to people vulnerable to the rhythm disruption during the COVID-19 pandemic.

Measuring circadian function in bipolar disorders: Empirical and conceptual review of physiological, actigraphic, and self-report approaches

BACKGROUND

Interest in biological clock pathways in bipolar disorders (BD) continues to grow, but there has yet to be an audit of circadian measurement tools for use in BD research and practice.

PROCEDURE

The International Society for Bipolar Disorders Chronobiology Task Force conducted a critical integrative review of circadian methods that have real-world applicability. Consensus discussion led to the selection of three domains to review-melatonin assessment, actigraphy, and self-report.

RESULTS

Measurement approaches used to quantify circadian function in BD are described in sufficient detail for researchers and clinicians to make pragmatic decisions about their use. A novel integration of the measurement literature is offered in the form of a provisional taxonomy distinguishing between circadian measures (the instruments and methods used to quantify circadian function, such as dim light melatonin onset) and circadian constructs (the biobehavioral processes to be measured, such as circadian phase).

CONCLUSIONS

Circadian variables are an important target of measurement in clinical practice and biomarker research. To improve reproducibility and clinical application of circadian constructs, an informed systematic approach to measurement is required. We trust that this review will decrease ambiguity in the literature and support theory-based consideration of measurement options.

Clarifying the role of sleep in depression: A narrative review

It has been established that 4.4 to 20% of the general population suffers from a major depressive disorder (MDD), which is frequently associated with a dysregulation of normal sleep-wake mechanisms. Disturbances of circadian rhythms are a cardinal feature of psychiatric dysfunctions, including MDD, which tends to indicate that biological clocks may play a role in their pathophysiology. Thus, episodes of depression and mania or hypomania can arise as a consequence of the disruption of zeitgebers (time cues). In addition, the habit of sleeping at a time that is out of phase with the body's other biological rhythms is a common finding in depressed patients. In this review, we have covered a vast area, emerging from human and animal studies, which supports the link between sleep and depression. In doing so, this paper covers a broad range of distinct mechanisms that may underlie the link between sleep and depression. This review further highlights the mechanisms that may underlie such link (e.g. circadian rhythm alterations, melatonin, and neuroinflammatory dysregulation), as well as evidence for a link between sleep and depression (e.g. objective findings of sleep during depressive episodes, effects of pharmacotherapy, chronotherapy, comorbidity of obstructive sleep apnea and depression), are presented.

Social stress and glucocorticoids alter PERIOD2 rhythmicity in the liver, but not in the suprachiasmatic nucleus

Circadian (~24 h) rhythms in behavior and physiological functions are under control of an endogenous circadian pacemaker in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN directly drives some of these rhythms or serves as a coordinator of peripheral oscillators residing in other tissues and organs. Disruption of the circadian organization may contribute to disease, including stress-related disorders. Previous research indicates that the master clock in the SCN is resistant to stress, although it is unclear whether stress affects rhythmicity in other tissues, possibly mediated by glucocorticoids, released in stressful situations. In the present study, we examined the effect of uncontrollable social defeat stress and glucocorticoid hormones on the central and peripheral clocks, respectively in the SCN and liver. Transgenic PERIOD2::LUCIFERASE knock-in mice were used to assess the rhythm of the clock protein PERIOD2 (PER2) in SCN slices and liver tissue collected after 10 consecutive days of social defeat stress. The rhythmicity of PER2 expression in the SCN was not affected by stress exposure, whereas in the liver the expression showed a delayed phase in defeated compared to non-defeated control mice. In a second experiment, brain slices and liver samples were collected from transgenic mice and exposed to different doses of corticosterone. Corticosterone did not affect PER2 rhythm of the SCN samples, but caused a phase shift in PER2 expression in liver samples. This study confirms earlier findings that the SCN is resistant to stress and shows that clocks in the liver are affected by social stress, which might be due to the direct influence of glucocorticoids released from the adrenal gland.

Light-exposure at night impairs mouse ovary development via cell apoptosis and DNA damage

The alternation of light and dark rhythm causes a series of physiological, biochemical and metabolic changes in animals, which also alters the growth and development of animals, and feeding, migration, reproduction and other behavioral activities. In recent years, many studies have reported the effects of long-term (more than 6 weeks) illumination on ovarian growth and development. In the present study, we observed the damage, repair and apoptosis of ovarian DNA in a short period of illumination. The results showed that, in short time (less than 2 weeks) illumination conditions, the 24-h light treatment caused the reduction of total ovarian follicle number and down-regulation of circadian clock related genes. Furthermore, the changed levels of serum sex hormones were also detected after 24-h light exposure, of which the concentrations of LH (luteinizing hormone), FSH (follicle-stimulating hormone) and E2 (estradiol) were increased, but the concentration of PROG (progesterone) was decreased. Moreover, 24-h light exposure increased the expression of DNA damage and repair related genes, the number of TUNEL and RAD51 positive cells. These results indicated that 24-h light exposure for 4, 8 and 12 days increased DNA damage and cell apoptosis, thereby affecting the development of ovary.

Circadian rhythms and mood: opportunities for multi-level analyses in genomics and neuroscience: circadian rhythm dysregulation in mood disorders provides clues to the brain's organizing principles, and a touchstone for genomics and neuroscience

In the healthy state, both circadian rhythm and mood are stable against perturbations, yet they are capable of adjusting to altered internal cues or ongoing changes in external conditions. The dual demands of stability and flexibility are met by the collective properties of complex neural networks. Disruption of this balance underlies both circadian rhythm abnormality and mood disorders. However, we do not fully understand the network properties that govern the crosstalk between the circadian system and mood regulation. This puzzle reflects a challenge at the center of neurobiology, and its solution requires the successful integration of existing data across all levels of neural organization, from molecules, cells, circuits, network dynamics, to integrated mental function. This essay discusses several open questions confronting the cross-level synthesis, and proposes that circadian regulation, and its role in mood, stands as a uniquely tractable system to study the causal mechanisms of neural adaptation.

Application of an ex vivo cellular model of circadian variation for bipolar disorder research: a proof of concept study

OBJECTIVES

Disruption of circadian function has been observed in several human disorders, including bipolar disorder (BD). Research into these disorders can be facilitated by human cellular models that evaluate external factors (zeitgebers) that impact circadian pacemaker activity. Incorporating a firefly luciferase reporter system into human fibroblasts provides a facile, bioluminescent readout that estimates circadian phase, while leaving the cells intact. We evaluated whether this system can be adapted to clinical BD research and whether it can incorporate zeitgeber challenge paradigms.

METHODS

Fibroblasts from patients with bipolar I disorder (BD-I) (n = 13) and controls (n = 12) were infected ex vivo with a lentiviral reporter incorporating the promoter sequences for Bmal1, a circadian gene to drive expression of the firefly luciferase gene. Following synchronization, the bioluminescence was used to estimate period length. Phase response curves (PRCs) were also generated following forskolin challenge and the phase response patterns were characterized.

RESULTS

Period length and PRCs could be estimated reliably from the constructs. There were no significant case-control differences in period length, with a nonsignificant trend for differences in PRCs following the phase-setting experiments.

CONCLUSIONS

An ex vivo cellular fibroblast-based model can be used to investigate circadian function in BD-I. It can be generated from specific individuals and this could usefully complement ongoing circadian clinical research.

Biological rhythms and mood disorders

Integration of several approaches concerning time and temporality can enhance the pathophysiological study of major mood disorders of unknown etiology. We propose that these conditions might be interpreted as disturbances of temporal profile of biological rhythms, as well as alterations of time-consciousness. Useful approaches to study time and temporality include philological suggestions, phenomenological and psychopathological conceptualizatíons, clinical descriptions, and research on circadian and ultradían rhythms, as well as nonlinear dynamics approaches to their analysis.

Oscillatory serotonin function in depression

Oscillations in brain activities with periods of minutes to hours may be critical for normal mood behaviors. Ultradian (faster than circadian) rhythms of mood behaviors and associated central nervous system activities are altered in depression. Recent data suggest that ultradian rhythms in serotonin (5HT) function also change in depression. In two separate studies, 5HT metabolites in cerebrospinal fluid (CSF) were measured every 10 min for 24 h before and after chronic antidepressant treatment. Antidepressant treatments were associated with enhanced ultradian amplitudes of CSF metabolite levels. Another study used resting-state functional magnetic resonance imaging (fMRI) to measure amplitudes of dorsal raphé activation cycles following sham or active dietary depletions of the 5HT precursor (tryptophan). During depletion, amplitudes of dorsal raphé activation cycles increased with rapid 6 s periods (about 0.18 Hz) while functional connectivity weakened between dorsal raphé and thalamus at slower periods of 20 s (0.05 Hz). A third approach studied MDMA (ecstasy, 3,4-methylenedioxy-N-methylamphetamine) users because of their chronically diminished 5HT function compared with non-MDMA polysubstance users (Karageorgiou et al., 2009). Compared with a non-MDMA using cohort, MDMA users showed diminished fMRI intra-regional coherence in motor regions along with altered functional connectivity, again suggesting effects of altered 5HT oscillatory function. These data support a hypothesis that qualities of ultradian oscillations in 5HT function may critically influence moods and behaviors. Dysfunctional 5HT rhythms in depression may be a common endpoint and biomarker for depression, linking dysfunction of slow brain network oscillators to 5HT mechanisms affected by commonly available treatments. 5HT oscillatory dysfunction may define illness subtypes and predict responses to serotonergic agents. Further studies of 5HT oscillations in depression are indicated.

Beneficial behavioural and neurogenic effects of agomelatine in a model of depression/anxiety

Agomelatine (S20098) is a novel antidepressant drug with melatonergic agonist and 5-HT2C receptor antagonist properties, displaying antidepressant/anxiolytic-like properties in animal models and in humans. In a depression/anxiety-like mouse model in which the response of the HPA axis is blunted, we investigated whether agomelatine could reverse behavioural deficits related to depression/anxiety compared to the classical selective serotonin reuptake inhibitor, fluoxetine. Adult mice were treated for 8 wk with either vehicle or corticosterone (35 μg/ml.d) via drinking water. During the final 4 wk, animals were treated with vehicle, agomelatine (10 or 40 mg/kg i.p.) or fluoxetine (18 mg/kg i.p.) and tested in several behavioural paradigms and also evaluated for home-cage activity. Our results showed that the depressive/anxiety-like phenotype induced by corticosterone treatment is reversed by either chronic agomelatine or fluoxetine treatment. Moreover, agomelatine increased the dark/light ratio of home-cage activity in vehicle-treated mice and reversed the alterations in this ratio induced by chronic corticosterone, suggesting a normalization of disturbed circadian rhythms. Finally, we investigated the effects of this new antidepressant on neurogenesis. Agomelatine reversed the decreased cell proliferation in the whole hippocampus in corticosterone-treated mice and increased maturation of newborn neurons in both vehicle- and corticosterone-treated mice. Overall, the present study suggests that agomelatine, with its distinct mechanism of action based on the synergy between the melatonergic agonist and 5-HT2C antagonist properties, provides a distinct antidepressant/anxiolytic spectrum including circadian rhythm normalization.

Differential association of circadian genes with mood disorders: CRY1 and NPAS2 are associated with unipolar major depression and CLOCK and VIP with bipolar disorder

Disruptions in circadian rhythms have been described in mood disorders (MD), but the involvement of genetic variation in genes pertaining to the molecular circadian machinery in the susceptibility to MD has not been conclusively determined. We examined 209 single-nucleotide polymorphisms (SNPs) covering 19 circadian genes (ADCYAP1, ARNTL, ARNTL2, BHLHB2, BHLHB3, CLOCK, CRY1, CRY2, CSNK1E, DBP, NPAS2, NR1D1, PER1, PER2, PER3, RORA, TIMELESS, VIP, and VIPR2) in a sample of 534 MD patients (335 with unipolar major mood depression (MDD) and 199 with bipolar disorder (BD)) and 440 community-based screened controls. Nominally, statistically significant associations were found in 15 circadian genes. The gene-wide test, corrected for the number of SNPs analyzed in each gene, identified significant associations in CRY1 (rs2287161), NPAS2 (rs11123857), and VIPR2 (rs885861) genes with the combined MD sample. In the MDD subsample, the same SNPs in CRY1 and NPAS2 of the combined sample remained associated, whereas in the BD subsample CLOCK (rs10462028) and VIP (rs17083008) were specifically associated. The association with an SNP located 3' near CRY1 gene in MDD remained statistically significant after permutation correction at experiment level (p=0.007). Significant additive effects were found between the SNPs that were statistically significant at the gene-wide level. We also found evidence of associations between two-marker haplotypes in CRY1 and NPAS2 genes and MD. Our data support the contribution of the circadian system to the genetic susceptibility to MD and suggest that different circadian genes may have specific effects on MD polarity.

Focus on HTR2C: A possible suggestion for genetic studies of complex disorders

HTR2C is one of the most relevant and investigated serotonin receptors. Its role in important brain structures such as the midbrain, the lateral septal complex, the hypothalamus, the olfactory bulb, the pons, the choroid plexus, the nucleus pallidus, the striatum and the amygdala, the nucleus accumbens and the anterior cingulated gyrus candidate it as a promising target for genetic association studies. The biological relevance of these brain structures is reviewed by way of the focus on HTR2C activity, with a special attention paid to psychiatric disorders. Evidence from the genetic association studies that dealt with HTR2C is reviewed and discussed alongside the findings derived from the neuronatmic investigations. The reasons for the discrepancies between these two sets of reports are discussed. As a result, HTR2C is shown to play a pivotal role in many different psychiatric behaviors or psychiatric related disrupted molecular balances, nevertheless, genetic association studies brought inconsistent results so far. The most replicated association involve the feeding behavior and antipsychotic induced side effects, both weight gain and motor related: Cys23Ser (rs6318) and -759C/T (rs3813929) report the most consistent results. The lack of association found in other independent studies dampens the clinical impact of these reports. Here, we report a possible explanation for discrepant findings that is poorly or not at all usually considered, that is that HTR2C may exert different or even opposite activities in the brain depending on the structure analyzed and that mRNA editing activity may compensate possible genetically controlled functional effects. The incomplete coverage of the HTR2C variants is proposed as the best cost-benefit ratio bias to fix. The evidence of brain area specific HTR2C mRNA editing opens a debate about how the brain can differently modulate stress events, and process antidepressant treatments, in different brain areas. The mRNA editing activity on HTR2C may play a major role for the negative association results.

Replicable differences in preferred circadian phase between bipolar disorder patients and control individuals

Morningness/eveningness (M/E) is a stable, quantifiable measure reflecting preferred circadian phase. Two prior studies suggest that bipolar I disorder (BP1) cases are more likely to have lower M/E scores, i.e., be evening types compared with control groups. These studies did not recruit controls systematically and did not evaluate key clinical variables. We sought to replicate the reported associations in a large, well defined sample, while evaluating potential confounding factors. Adults with bipolar disorder (BP) were compared with community controls drawn randomly from the same residential areas (190 cases and 128 controls). M/E was evaluated using the composite scale of morningness (CSM). After accounting for variables correlated with M/E, BP cases had significantly lower CSM scores than controls (i.e., more evening-type or fewer morning-type). There were no significant differences in M/E scores between BP1 or BP2 disorder cases (n=134 and 56, respectively). CSM scores were stable over approximately 2 years in a subgroup of participants (n=52). Individuals prescribed anxiolytic drugs, antidepressants, antipsychotic drugs, mood stabilizers or stimulant drugs had significantly lower age-corrected CSM scores compared with persons not taking these drugs. BP cases are more likely to be evening types, suggesting circadian phase delay in BP cases. Individuals with elevated depressive mood scores are more likely to be evening types. Our results suggest a replicable relationship between circadian phase and morbid mood states.

Assessment of circadian function in fibroblasts of patients with bipolar disorder

Previous studies have implicated the circadian system in the pathophysiology of bipolar disorder, but conclusive evidence for altered circadian clocks is lacking. Cultured fibroblasts harbor circadian clocks representative of those in the master clock resident in the suprachiasmatic nuclei, providing a new avenue to investigate the core clock machinery in patients with bipolar illness. We examined the rhythmic expression patterns of core clock genes (BMAL1, PER1, PER2, REV-ERBalpha, DEC2, DBP) in fibroblasts from 12 bipolar patients and 12 healthy controls. Although we did not detect differences in the circadian period between bipolar patients and controls, the amplitude of rhythmic expression for BMAL1, REV-ERBalpha and DBP, as well as the overall mRNA expression level for DEC2 and DBP was reduced in fibroblasts from bipolar patients. Bonferroni's correction for multiple comparisons still resulted in significantly reduced DBP expression level, and trends toward reduced overall expression level of DEC2 and circadian amplitude of BMAL1, in fibroblasts from bipolar patients. We next examined an expanded cohort of 18 bipolar patients and 35 healthy controls for mRNA expression levels of four kinases (CKIdelta, CKIepsilon, GSK3alpha and GSK3beta) and the protein and phosphorylation levels of two of them (GSK3alpha and GSK3beta). We did not detect differences in steady-state mRNA levels or protein levels of these kinases between bipolar patients and controls, but the level of GSK3beta phosphorylation was significantly reduced in bipolar patients within an Old Order Amish bipolar kindred. Our results suggest that the reduced amplitudes and overall expression levels of circadian genes, and the decreased phosphorylation level of GSK3beta may lead to dysregulation of downstream genes, which could explain some pathological features of bipolar disorder.

Response styles to depressed mood in bipolar affective disorder

BACKGROUND

It has been hypothesised that dysfunctional strategies for avoiding depression play an important role in the pathway to mania. Support for this hypothesis comes from studies demonstrating that remitted and manic bipolar patients show similar cognitive biases to currently depressed patients.

METHOD

Manic patients, depressed bipolar patients, remitted bipolar patients and healthy controls were compared on an expanded version of Nolen-Hoeksema's [Nolen-Hoeksema, S., 1991. Responses to depression and their effects on the duration of depressed mood. Journal of Abnormal Psychology, 100, 569-582.] Response Styles Questionnaire, measuring strategies for coping with depression.

RESULTS

Manic patients reported greater use of active-coping and risk-taking compared to the depressed, remitted and healthy controls. Bipolar remitted patients reported greater rumination.

CONCLUSIONS

The findings are consistent with the hypothesis that mania is associated with dysfunctional strategies for regulating negative emotion.

Association study of eight circadian genes with bipolar I disorder, schizoaffective disorder and schizophrenia

We hypothesize that circadian dysfunction could underlie, at least partially, the liability for bipolar 1 disorder (BD1). Our hypothesis motivated tests for the association between the polymorphisms of genes that mediate circadian function and liability for BD1. The US Caucasian patients with BD1 (DSM-IV criteria) and available parents were recruited from Pittsburgh and surrounding areas (n = 138 cases, 196 parents) and also selected from the NIMH Genetics Collaborative Initiative (n = 96 cases, 192 parents). We assayed 44 informative single-nucleotide polymorphisms (SNPs) from eight circadian genes in the BD1 samples. A population-based sample, specifically cord blood samples from local live births, served as community-based controls (n = 180). It was used as a contrast for genotype and haplotype distributions with those of patients. US patients with schizophrenia/schizoaffective disorder (SZ/SZA, n = 331) and available parents from Pittsburgh (n = 344) were assayed for a smaller set of SNPs based on the results from the BD1 samples. Modest associations with SNPs at ARNTL (BmaL1) and TIMELESS genes were observed in the BD1 samples. The associations were detected using family-based and case-control analyses, albeit with different SNPs. Associations with TIMELESS and PERIOD3 were also detected in the Pittsburgh SZ/SZA group. Thus far, evidence for association between specific SNPs at the circadian gene loci and BD1 is tentative. Additional studies using larger samples are required to evaluate the associations reported here.

Is there evidence for social rhythm instability in people at risk for affective disorders?

Social rhythm disruptions are thought to be related to the etiology of affective symptoms. 'Hypomanic personality' and 'rigidity' are hypothesized to be risk factors for affective disorders. We examined whether people scoring high on such scales would demonstrate instability of social rhythms and sleep. In a short-term prospective diary study with one group factor, the following three groups were selected from a non-university student sample: 'bipolar risk' (scoring high on the 'Hypomanic Personality Scale'; n=56); 'Unipolar risk' (scoring high on the 'Rigidity Scale'; n=37); and a control group (scoring low on both scales; n=48). The participants completed ratings of their activities and sleep for 28 days. People at risk for bipolar disorders showed a lower regularity of daily activities than controls. Their sleeping pattern was not characterized by fewer but by more variable hours of sleep. The unipolar risk group did not differ from the control group at all. Despite some limitations, there is partial evidence for social rhythm and sleep irregularities in people putatively at risk for bipolar disorders. Further research is, however, needed to replicate and extend these results.

Treatment enhances ultradian rhythms of CSF monoamine metabolites in patients with major depressive episodes

Unipolar and bipolar depressions show abnormal behavioral manifestations of ultradian (less than 24 h) rhythms, but abnormal rhythms of the central neurotransmitters thought to be important for depression pathophysiology (eg dopamine (DA) and serotonin (5-HT)) have not been shown in this time frame. Since antidepressant treatments normalize disrupted rhythms in depression (eg rapid-eye-movement sleep and hormonal rhythms), we hypothesized that depression-related changes in ultradian oscillations of DA and 5-HT might be revealed during antidepressant treatment. Cerebrospinal fluid (CSF) samples collected q10 min for 24 h in 13 patients experiencing major depressive episodes (MDE) before and after treatment for 5 weeks with sertraline or bupropion were assayed for levels of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), and their ratio was calculated. Data were analyzed in the frequency domain using Fourier transforms and multivariate permutation testing. Antidepressant treatments were associated with decreased variance for 5-HIAA, increased variance for HVA, and markedly increased variance for the HVA : 5-HIAA ratio (p<0.05, p<0.02, and p<0.003, respectively). With treatment, the correlations between 5-HIAA and HVA weakened (p=0.06). Power spectral density (PSD-the Fourier magnitude squared) of the 5-HIAA signals at periods of 1.75 and 3.7 h (both p<0.05) decreased, while circadian cycling of HVA levels (p<0.05) and of the ratio (p<0.005) increased after treatment. The PSD of the full-length HVA : 5-HIAA ratio series after treatment increased in rapid variability (20-103 min periods, p<0.05). Spectrographic windowing demonstrated a focal span of enhanced HVA : 5-HIAA ratio variability following antidepressant treatment, in an approximately 84-min period through the evening (p<0.05). Periodic neurotransmitter relationships in depressed patients were altered by treatment in this analysis of a small data set. This may represent a baseline abnormality in the regulation of periodic functions involved in the depression pathophysiology, but it could also be due to an unrelated antidepressant effect. Further studies including comparisons with healthy subject data are in progress.

Rest-activity cycles in childhood and adolescent depression

OBJECTIVE

To quantify circadian rhythms in rest-activity cycles in depressed children and adolescents.

METHOD

Rest-activity cycles were evaluated by actigraphy over five consecutive 24-hour periods in 100 children and adolescents, including 59 outpatients with major depressive disorder (MDD) and 41 healthy normal controls. Total activity, total light exposure, and time spent in light at more than 1,000 lux were averaged over the recording period for each participant. Time series analysis was used to determine the amplitude and period length of circadian rhythms in rest-activity.

RESULTS

Overall, adolescents with MDD had lower activity levels, damped circadian amplitude, and lower light exposure and spent less time in bright light than healthy controls. Among children, those with MDD showed lower light exposure and spent less time in bright light, but only depressed girls showed damped circadian amplitude. The sex differences were substantially greater in the MDD group than in the normal control group.

CONCLUSIONS

These results confirm damped circadian rhythms in children and adolescents with MDD and highlight the influence of gender and age on these measures.

Diurnal variation of cerebrospinal fluid hypocretin-1 (Orexin-A) levels in control and depressed subjects

BACKGROUND

Hypocretins, excitatory neuropeptides at monoaminergic synapses, appear to regulate human sleep-wake cycles. Undetectable cerebrospinal fluid hypocretin-1 levels are seen in narcolepsy, which is frequently associated with secondary depression. Shortened rapid eye movement latency is observed in both narcolepsy and depression. Cerebrospinal fluid hypocretin-1 levels have not been reported in mood disorders.

METHODS

We examined hypocretin-1 levels in 14 control and 15 depressed subjects. Cerebrospinal fluid was drawn continuously in supine subjects for 24 hours with an indwelling intrathecal catheter under entrained light-dark conditions. Depressed subjects were studied before and after 5 weeks of sertraline (n=10, three nonresponders) or bupropion (n=5, two nonresponders).

RESULTS

Hypocretin-1 levels varied slightly (amplitude 10%) but significantly across the diurnal cycle in control subjects, with amplitude significantly reduced in depression (3%). Levels were lowest at midday, surprising for a hypothetically wake-promoting peptide. Mean hypocretin levels trended higher in depressive than in control subjects. Hypocretin-1 levels decreased modestly but significantly after sertraline (-14%) but not bupropion.

CONCLUSIONS

Our results are consistent with previous physiologic findings in depression indicating dampened diurnal variations in hypocretin-1. The finding that sertraline but not bupropion slightly decreased cerebrospinal fluid hypocretin-1 indicates a serotoninergic influence on hypocretin tone.

Weak 24-h periodicity of body temperature and increased plasma vasopressin in melancholic depression

Earlier work has shown that plasma vasopressin levels of depressed patients were higher than those of healthy controls. The aim of the present study was to determine whether plasma vasopressin levels were correlated to parameters of the circadian rhythm. Forty-one patients with major depression and twenty-five controls participated in a case-control design under natural circumstances in a field study to investigate plasma vasopressin levels three times daily, circadian motor activity, and the 24-h periodicity of body temperature for five consecutive 24-h periods. Temperature measurements consisted of at least five, but mostly six or more measurements every 24 h. Twenty-two percent of the patients, but none of the controls lacked 24-h periodicity of body temperature. In melancholic patients increased vasopressin levels in plasma correlated with a weak 24-h periodicity of body temperature. The role of vasopressin is discussed in the light of the present findings.

Psychiatric aspects of jet lag: review and hypothesis

Jet lag is a travel-induced circadian rhythm phenomenon that afflicts healthy individuals following long- distance flights through several time zones. The typical jet-lag manifestations - insomnia during local sleep time, day fatigue, reduced concentration, irritability, and exhaustion with mild depression - are attributed to transient desynchronization in the circadian rhythm until the internal biological clock is rephased to the new environmental conditions. There is strong evidence relating affective disorders with circadian rhythm abnormalities. Less convincing suggestions relate jet lag to psychosis. It can be hypothesized that in predisposed individuals jet lag may play a role in triggering exacerbation or even de novo affective disorders. Furthermore, we propose the possibility that psychosis and even schizophrenia can be elicited by jet lag. This outlook gains its support from case studies and some common underlying phase-advanced biological denominators involved in both jet lag sufferers and psychotic patients.

3,4-dihydro-2(1H)-quinolinone as a novel antidepressant drug: synthesis and pharmacology of 1-[3-[4-(3-chlorophenyl)-1-piperazinyl]propyl]-3,4- dihydro-5-methoxy-2(1H)-quinolinone and its derivatives

To develop a novel antidepressant drug with central nervous system-stimulating activity, we prepared a series of 1-[omega-(4-substituted phenyl-1-piperazinyl)alkyl]-3, 4-dihydro-2(1H)-quinolinone derivatives and examined their activities by their effects at 30 and 100 mg/kg po on the sleeping time of mice anesthetized with halothane and on the time required for recovery from coma induced in mice by cerebral concussion. We examined their binding affinities for sigma receptors by evaluating their ability to inhibit [(3)H]-1,3-di(o-tolyl)guanidine ([(3)H]DTG) binding to the rat whole brain membrane in comparison with three putative sigma receptor agonists: 1,3-di(o-tolyl)guanidine (DTG, 66), (+)-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2, 6-methano-3-benzazecin-8-ol (SKF10,047, 67), and (+)-1,2,3,4,5, 6-hexahydro-6,11-dimethyl-3-(3-methyl-2-butenyl)-2, 6-methano-3-benzazecin-8-ol (pentazocine, 68). Among the series of derivatives, 1-[3-[4-(3-chlorophenyl)-1-piperazinyl]propyl]-3, 4-dihydro-5-methoxy-2(1H)-quinolinone hydrochloride (34b) and its mesylate (34c), at a dose of 30 mg/kg po, reduced the sleeping time and the time for recovery from coma and they inhibited [(3)H]DTG binding for sigma receptors. The putative sigma receptor agonists reduced the sleeping time and the time for recovery from coma whereas two sigma receptor antagonists, alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazinebutanol hydrochloride (BMY14802, 69) and cis-9-[3-(3, 5-dimethyl-1-piperazinyl)propyl]carbazole dihydrochloride (rimcazole, 70), were inactive in the two tests. Preadministration of the putative sigma receptor antagonists 69 (3 mg/kg po) and 70 (30 mg/kg po) completely antagonized the actions of 34b and the sigma receptor agonists in the test for recovery from coma. These results suggested that 34b and 34c are sigma receptor agonists. Furthermore, a single administration of 1 and 10 mg/kg po 34b and 34c showed antidepressant-like activity by reducing the immobility time in the forced-swimming test with mice, while a tricyclic antidepressant, 10, 11-dihydro-N,N-dimethyl-5H-dibenz[b,f]azepine-5-propanamine hydrochloride (imipramine, 1) (10 and 30 mg/kg po), did not reduce the time after a single administration. 1 reduced the time after repeated administration of 30 mg/kg po once a day for 4 days. The structure-activity relationship of the series of compounds is also discussed.

A re-evaluation of social defeat as an animal model of depression

Social defeat by aggressive Tryon Maze Dull (TMD) rats, resulting in loss of rank of a previously dominant rat, has recently been advanced as a model of loss of self-esteem in humans. Since low self-esteem is a major symptom of depression, a further claim has been made that loss of rank can be used as a model of depression. In support of this claim, it has been suggested that loss of rank can be reversed by the antidepressant imipramine. However, antidepressant treatment has not yet been shown to reverse the effects of defeat for more than a single test session. Consequently, the present study was designed to more fully assess the effects of antidepressant treatment on the behaviour of defeated animals. Six pairs of male Lister Hooded (LH) rats were observed biweekly for 30 min at the onset of the dark phase of the light-dark cycle. In five of the six pairs, a stable social hierarchy (assessed by the observation of aggressive behaviours such as attacks and pushes, and submissive behaviours such as submissive posture) was established over a period of 10 weeks. The dominant animals of these five pairs were defeated once a week, in the home cage, by a singly housed male TMD for a period of 15 min. After 5 weeks of defeat by TMD, all five of the dominant animals showed an effect of defeat on behaviours relevant to status, although a reversal in status within the LH pairs was apparent in only one case. All defeated animals, regardless of whether or not defeat affected status, received daily injections of imipramine (5 mg/kg) for 5 weeks. Imipramine markedly worsened behaviours relevant to status in the treated animals. Indeed, animals treated with imipramine were more likely to lose encounters with their cage-mates. Consequently, the results cast doubt on the validity of social defeat as a model of depression, at least when the effects of defeat are assessed in terms of social status.

Characterization of melatonin-induced fos-like immunoreactivity in the hypothalamic suprachiasmatic nucleus of the rat

The hypothalamic suprachiasmatic nucleus (SCN) is primarily responsible for the regulation of circadian rhythmicity. Melatonin, the pineal-derived neurohormone, modulates the rhythmic output of the SCN. Property timed exposure to melatonin is able to induce changes in rhythmic function and thereby entrain circadian rhythms of activity. c-fos is an immediate early gene that is transiently expressed in neurons in response to receptor activation. The ventrolateral portion of the SCN (vSCN) is activated in response to phase-shifting stimuli, an event which is marked by an increase in the expression of c-fos.

Conservation of locomotor behavior in the golden hamster: effects of light cycle and a circadian period mutation

Locomotor activity in rodents is restricted temporally by the animal' s circadian system. The relative stability of both the species-specific pattern and the amount of locomotor activity per cycle suggested that this behavior may be regulated by conservative mechanisms. In these experiments, the wheel-running behavior of golden hamsters carrying the circadian period mutation, tau, was analyzed in animals housed in a 24-h light:dark cycle (LD) and in constant dark (DD) conditions to determine which aspects of this behavior were conserved. In DD, apart from the change in period which defines the mutation, no main effects of allele combination were found in either average amount of activity, activity profile, or length of the activity phase. In LD, wild-type behavior did not differ from that in DD; however, heterozygous mutants exhibited early onsets of activity, significant fragmentation of both activity and rest, an increase in the duration of the active phase, and an overall decrease in the amount of activity. Despite these differences, the total amount of time spent on the wheel in LD or DD was the same for all environment/genotype combinations. The data show that a conservative mechanism that may influence daily patterns of locomotor behavior is related more to a drive to perform the behavior than the quantity or timing of the behavior itself.

Neonatal clomipramine treatment of Syrian hamsters: effect on the circadian system

The circadian behavior of male Syrian hamsters injected with the serotonin/norepinephrine reuptake inhibitor clomipramine (15 mg/kg from postnatal days 8 to 21) was examined. Clomipramine treatment significantly augmented mean activity values of wheel running rhythm, as well as delayed its acrophase. After a 6-h phase advance of the light-dark cycle, reentrainment of clomipramine-treated hamsters took significantly longer than controls. Clomipramine-treated hamsters exhibited a shorter circadian period than controls in constant light conditions, but no differences were found in constant darkness. Light pulses applied at late subjective night to clomipramine-treated hamsters caused significantly reduced phase advances as compared to controls, while no differences were found in phase delay magnitudes when light pulses were applied during early subjective night. Administration of the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) at circadian time 8 significantly advanced the onset of activity to a greater extent in clomipramine-treated hamsters than in controls. The results indicate that neonatal clomipramine treatment of hamsters causes long-lasting changes in the circadian system, by increasing activity levels and by partially inhibiting light-evoked responses. An enhancement of a non-photic, serotonergic-induced response was also unveiled.

Electroconvulsive therapy increases circadian amplitude and lowers core body temperature in depressed subjects

BACKGROUND

Reduced amplitude of the circadian temperature rhythm and elevated nocturnal body temperature normalize after successful pharmacotherapy of major depression.

METHODS

Core body temperature was continually monitored in three groups: a) 6 depressed patients before an electroconvulsive therapy (ECT) course and b) after an ECT course; and c) 6 healthy, sex-matched controls of similar age.

RESULTS

The 24-hour profile of temperature was significantly different in patients pre-ECT than in patients post-ECT or in controls. Post-ECT subjects and controls manifested 24-hour profiles similar to one another. Circadian temperature rhythm amplitude increased after ECT. The mean asleep and mean 24-hour temperatures were significantly higher in patients pre-ECT than post-ECT and controls.

CONCLUSIONS

We find that ECT restores a disrupted circadian temperature rhythm in depressed patients.

Dysregulation of diurnal rhythms of serotonin 5-HT2C and corticosteroid receptor gene expression in the hippocampus with food restriction and glucocorticoids

Both serotonergic dysfunction and glucocorticoid hypersecretion are implicated in affective and eating disorders. The adverse effects of serotonergic (5-HT)2C receptor activation on mood and food intake, the antidepressant efficacy of 5-HT2 receptor antagonists, and the hyperphagia observed in 5-HT2C receptor knockout mice all suggest a key role for increased 5-HT2C receptor-mediated neurotransmission. Glucocorticoids, however, downregulate 5-HT2C receptor mRNA in the hippocampus, and it is unclear how increased 5-HT2C receptor sensitivity is achieved in the presence of elevated glucocorticoid levels in depression. Here we show a monophasic diurnal rhythm of 5-HT2C receptor mRNA expression in the rat hippocampus that parallels time-dependent variations in 5-HT2C receptor agonist-induced behaviors in open field tests. Rats entrained to chronic food restriction show marked but intermittent corticosterone hypersecretion and maintain an unaltered 5-HT2C receptor mRNA rhythm. The 5-HT2C receptor mRNA rhythm, however, is suppressed by even modest constant elevations of corticosterone (adrenalectomy + pellet) or with elevated corticosterone during the daytime (8 A.M.), whereas a normal rhythm exists in animals that have the same dose of corticosterone in the evening (6 P.M.). Thus, animals showing even a transient daytime corticosterone nadir exhibit normal hippocampal 5-HT2C receptor mRNA rhythms, even in the presence of overt corticosterone hypersecretion. Chronic food restriction also abolishes the normal diurnal variation in hippocampal glucocorticoid receptor (GR) and mineralocorticoid receptor mRNAs and produces, unusually, both elevated corticosterone and increased GR. The mismatch between elevated glucocorticoids and maintained 5-HT2C receptor and increased GR gene expression in the hippocampus provides a new model to dissect mechanisms that may underlie affective and eating disorders.

Case study: the use of melatonin in a boy with refractory bipolar disorder

The authors describe the clinical course of a 10-year-old boy with bipolar disorder diagnosed at age 5 years. Lithium, carbamazepine, and valproic acid were ineffective or caused intolerable side effects. A trial of melatonin led to rapid relief of insomnia and aborted a manic episode. He has continued to take melatonin and adjunctive alprazolam for 15 months without recurrence of insomnia or mania. Affective disorders involving circadian dysregulation may respond to interventions that restore a normal sleep-wake cycle. Literature supporting this hypothesis is cited.

Stress-induced changes in circadian rhythms of body temperature and activity in rats are not caused by pacemaker changes

Previous work has shown that social stress in rats (i.e., defeat by an aggressive male conspecific) causes a variety of behavioral and physiological changes including alterations in the daily rhythms of body temperature and activity. To study the role of the circadian pacemaker in these stress-induced changes, three experiments were performed, successively addressing pacemaker period, phase, and sensitivity to light. In all experiments, rats were subjected to social stress by placing them in the home cage of a dominant conspecific for 1 h. This was done on 2 consecutive days, between the second and fifth hours of the activity phase. Experimental animals were attacked by the resident and lost the fight as indicated by submissive behavior. Control animals were placed in an unfamiliar but clean and empty cage for 1 h. In Experiment 1, the effects of social stress on the period of the free-running activity rhythm were studied. Rats were individually housed under constant dim red light. Activity was measured with infrared detectors. Social defeat caused a reduction of activity for a number of days, but the period of the free-running rhythm was not affected. In Experiment 2, the authors studied whether social defeat induced acute phase shifts. Body temperature and activity were measured by means of radiotelemetry with intraperitoneally implanted transmitters. After the social interactions, experimental animals were kept under constant dim red light. Social stress caused a profound reduction in the amplitude of the body temperature and activity rhythm, but no significant phase shifts occurred. In Experiment 3, the authors studied whether social defeat affected the circadian pacemaker's sensitivity to light given that the size of light-induced phase shifts is thought to reflect pacemaker amplitude. Again, body temperature and activity were measured by means of telemetry. After double social defeat, animals were kept under continuous dim red light. One day after the second conflict, animals were subjected to a single 1-h light pulse (300 lux) at circadian time 14. The light pulse induced a phase delay of the body temperature rhythm, but there were no significant differences between the stress and control groups. The data indicate that stress-induced changes in activity and temperature rhythm, as well as behavioral and physiological changes found in earlier experiments, are not caused by changes in the circadian pacemaker. More generally, the data support the notion that overt rhythms are not always a reliable indication of pacemaker function.

Circadian rhythms and autoregulatory transcription loops--going round in circles?

Recent advances in the molecular analysis of biological timing have appeared to bring us closer to an answer to the 'big question', namely, 'What is the timing mechanism that enables an organism to measure the circadian (around 24 h) period?'. In this minireview, we consider the validity of the fashionable concept that autoregulatory feedback loops, centered on transcription, form the basis of the clock, and we offer a fresh view of recent progress as it relates to mammalian systems.

Effect of chronic mild stress on circadian rhythms in the locomotor activity in rats

The purpose of this study was to assess whether the chronic mild stress (CMS) procedure, as a realistic animal model of depression, affects the rhythms of the locomotor activity in rats. Rhythm parameters (period, mesor, amplitude, acrophase, and percent rhythm) were estimated from the best-fitted cosine function curves. Period is the length, mesor is the mean level, amplitude (A) is the extent, acrophase is the timing of the rhythm; percent rhythm represents the variability estimated by the cosine regression and expressed as a percentage of the total variability of raw data. The animals were kept on the 12 L : 12 D cycle during 13 weeks of the experiment and subjected to CMS for first 4 weeks. In week 5 the rats were under the constant light for 24 h a day (LL), and in week 9, under the constant darkness (DD). In LD 12:12 CMS decreased the activity in the dark phase by approximately 50% (p < 0.01) and did not change the activity in the light phase, resulting in a drop of the 24 h activity by about 40% in comparison to controls. The amplitude of diurnal variations of the activity was highly statistically different from zero at p(A = 0) < 0.0001, and the percent rhythm was in range of 40-75% in both the CMS and control groups. The mesor and the amplitude of the diurnal rhythm (with a period of 24 h) in the CMS rats were significantly (p < 0.001) lower than those in the control. In LL, the activity of both groups was diminished about 50% during the subjective dark phase. On the other hand, in the subjective light phase the activity of CMS rats only was diminished. The percent rhythm for the CMS and control rats was 30 and 58%, respectively, and values of mesor, amplitude, and acrophase for both groups were highly statistically different. In DD, the activity in the CMS group was statistically significantly lower in both the subjective dark and light phases. In contrast to the results from LL, the cosine curves from DD were similarly shifted in relation to the subjective light-dark cycle. After a restoration of the LD cycle the levels of the 24-h activity of both groups became equal in the 13th week, but the light and dark phase differences between the groups were still statistically significant (p < 0.05). The present results indicate that CMS exerts distinct and prolonged disturbances of the diurnal and circadian rhythms of the locomotor activity in the rats.

Circadian variation of plasma cobalamin, transcobalamin-bound cobalamin and unsaturated binding capacity of transcobalamin and haptocorrin in healthy elderly

Blood samples were drawn every second hour during a 24-h period from healthy elderly subjects. Plasma levels of cobalamin, albumin, transcobalamin-bound cobalamin and unsaturated binding capacity of transcobalamin and haptocorrin were determined. During night, all components decreased in parallel with plasma albumin. The nocturnal decreases were therefore ascribed to plasma volume changes due to bed-rest. Reports on the recently proposed role of cobalamin for the biological clock were reviewed, but the proposed role could not be explained by this study.

The circadian system and the therapeutics of the affective disorders

Establishing that a circadian rhythm is abnormal tells us little about the cause, which can arise from changes in the patient's lifestyle, irregularities of the body clock or a malfunction in the process of entrainment of the clock. In a clinical context, such a range of possible explanations implies differences in the most appropriate mode of treatment. Against this background, the conventional view that the underlying abnormality in endogenous depression is due to a disorder of the body clock is challenged. The challenge is based on difficulties of interpretation of the clinical data and the results of studies on circadian rhythms in patients. It is suggested that the state of the circadian system in depression resembles its state in healthy individuals after time-zone transitions or in shift work maladaptation syndrome and that this disturbance should be seen as resulting from changes in the phasing of external zeitgebers rather than from an abnormality in the clock itself.

Can the DRL 72s schedule selectively reveal antidepressant drug activity?

The effects of three antidepressants, desipramine (2.5-20 mg/kg) tranylcypromine (0.63-2.5 mg/kg) mianserin (1.25-10 mg/kg) and three non-antidepressants, chlordiazepoxide (CDP; 1.25-10 mg/kg) haloperidol (0.02-0.16 mg/kg) d-amphetamine (0.31-1.25 mg/kg) were evaluated in rats responding for water reinforcement under a DRL 72s schedule. The antidepressants all produced dose-related decreases in overall response rates, but no significant changes in reinforcement frequency. In contrast, the anxiolytic CDP did increase the number of reinforcers obtained. Haloperidol decreased both reinforcers and responses whilst d-amphetamine stimulated responding, thereby decreasing reinforcement frequency. An analysis of the modes of inter-response times (IRTs) revealed no significant shifts in the peaks of the IRT distributions for most of the drugs tested. Amphetamine, however, (0.31 and 0.63 mg/kg) decreased the modal values in correspondence with the shift to the left of the peak of responding caused by this compound. These results are discussed in the context of the use of the DRL 72s procedure as a screening test for antidepressant drugs.

Diurnal variation of mood and neuropsychological function in major depression with melancholia

20 DSM-III-R melancholics with clinically evident diurnal symptoms and 20 controls were assessed with a battery of neuropsychological tests, a test of maximum voluntary hand-grip, and neuroendocrine measures of hypothalamic-pituitary-adrenal axis function morning and evening in a 24-h period, using a balanced design. The morning pattern of neuropsychological impairment in the melancholics was comprehensive, affecting attention and concentration/working memory, episodic memory, reaction time and, strikingly, the speed of simultaneous match to sample, which was performed more slowly than the version of the task delayed to 0 or 4 s. The melancholics were significantly weaker than controls, on a measure of maximal voluntary contraction. Significantly improved neuropsychological function was seen in the melancholic patients in the evening, in line with diurnal improvement in mood; there was also a large increase in strength. Slowing on the digit symbol substitution test, the simultaneous match to sample task, total errors on the match to sample and hand-grip remained impaired in the evening compared to controls; other neuropsychological measures were no longer statistically different from control values which were often worsened. Neuroendocrine measures showed significantly raised levels of cortisol and ACTH morning and evening in the melancholics. Morning cortisol in the melancholics correlated with the diurnal improvement in neuropsychological functioning. The results have implications for the timing of neuropsychological assessment in major depression. Indices of neuropsychological and motor function may be as reliable quantitative estimates of illness severity as subjective estimates of mood.

Alzheimer's disease: improvement of visual memory and visuoconstructive performance by treatment with picotesla range magnetic fields

Impairments in visual memory and visuoconstructive functions commonly occur in patients with Alzheimer's disease (AD). Recently, I reported that external application of electromagnetic fields (EMF) of extremely low intensity (in the picotesla range) and of low frequency (in the range of 5Hz-8Hz) improved visual memory and visuoperceptive functions in patients with Parkinson's disease. Since a subgroup of Parkinsonian patients, specifically those with dementia, have coexisting pathological and clinical features of AD, I investigated in two AD patients the effects of these extremely weak EMF on visual memory and visuoconstructive performance. The Rey-Osterrieth Complex Figure Test as well as sequential drawings from memory of a house, a bicycle, and a man were employed to evaluate the effects of EMF on visual memory and visuoconstructive functions, respectively. In both patients treatment with EMF resulted in a dramatic improvement in visual memory and enhancement of visuoconstructive performance which was associated clinically with improvement in other cognitive functions such as short term memory, calculations, spatial orientation, judgement and reasoning as well as level of energy, social interactions, and mood. The report demonstrates, for the first time, that specific cognitive symptoms of AD are improved by treatment with EMF of a specific intensity and frequency. The rapid improvement in cognitive functions in response to EMF suggests that some of the mental deficits of AD are reversible being caused by a functional (i.e., synaptic transmission) rather than a structural (i.e., neuritic plaques) disruption of neuronal communication in the central nervous system.

Biological aspects of depression

In most cases, depression involves the interaction of biological and psychosocial factors. The impact of biological factors seems to be more prominent in major depressive syndrome, where typical symptoms and signs such as decrease in weight, changes in libido, dysmenorrhea, and sleeping disorders cannot be explained on psychodynamic grounds alone. Some of the symptoms and signs typical of patients suffering from depression reflect a primary disorder of biochemical and neurophysiological functions and are not commonly found in other forms of psychic disturbances. Studies related to monoamine (noradrenaline, serotonin or 5-HT, dopamine) metabolism have assumed a major role in biochemical research into depression; this research now also includes studies on other central neurotransmitters such as GABA and glutamic acid, and neuropeptides like somatostatin and corticotropin-releasing factor (CRF). Several theories have been suggested for the biochemical background of depression, and these hypotheses can now be tested using new and sophisticated research methods. Recent progress in understanding receptor structure and function and the regulation of neuroendocrine functions will substantially increase our knowledge of the biological deviations in depression and eventually lead to better drugs and treatment strategies. In the following, current perspectives on the biology of depressive disorders are introduced. It seems clear that susceptibility to depression is linked with deviations in presynaptic and postsynaptic neurotransmitter turnover and function. These, in turn, may lead to alterations in other regulatory mechanisms, such as the neuroendocrine and immune systems.

Locomotor activity in depressed children and adolescents: I. Circadian dysregulation

OBJECTIVE

To determine whether circadian activity rhythms were altered in pediatric patients with depression. Evidence was sought for a shift in the timing of the rhythm, blunting of circadian amplitude, or emergence of noncircadian periodicities.

METHOD

Locomotor activity was quantified in 57 patients with major depressive mood disorders (mean age 12.4 years) and 16 normal controls (9.9 years). Activity was measured in 5-minute epochs during 72 hours using belt-worn electronic activity monitors.

RESULTS

Patients with mood disorders displayed a 15% decrease in the amplitude of their circadian rhythm, and a 52% increase in the magnitude of their twice-daily (hemicircadian) rhythm. No significant difference emerged in the timing of the circadian rhythm. Depressed inpatients and outpatients displayed comparable disturbances, which were most marked in adolescents.

CONCLUSIONS

Circadian activity rhythms were dysregulated in pediatric patients with major depression. These findings may have etiological and diagnostic significance.

Climate and admissions for mania in the tropics

Seasonality of admissions for mania has been commonly reported. Most reports are from temperature zones. We analyzed admissions for mania covering a 9 year period and looked for any seasonal trends using existing methods. No seasonal variation was found. The hospital lies in the tropical zone with a relatively constant climate. This may influence the seasonal pattern of relapses in affective disorder.