Internalizing symptoms and chronotype in youth: A longitudinal assessment of anxiety, depression and tripartite model.

Biological rhythm theories highlight the reciprocal relations between dysregulated circadian patterns and internalizing psychopathology. Chronotype characterizes individuals' diurnal preference, as some exhibit more morningness or eveningness. Previous research suggests that eveningness prospectively predicts depression in adolescence. Anxiety often co-occurs with depression, but little is known about longitudinal, reciprocal associations between chronotype and anxiety, and whether this relationship remains after controlling for depression. We assessed different forms of anxiety (social, panic, separation), positive/negative affect, anxious arousal (from tripartite theory), and depression, in relation to chronotype to better understand the specificity and directionality of associations between chronotype and internalizing problems in adolescence. Community youth participated in three assessment time points: T1, T2 (18-months post-T1), and T3 (30-months post-T1) as part of a larger longitudinal study. Youth completed self-report measures of anxiety, depression, positive and negative affect, and chronotype. Regression analyses showed that eveningness: (1) concurrently associated with decreased separation anxiety, elevated symptoms of depression and low levels of positive affect, (2) was prospectively predicted by elevated depression, (3) did not predict later symptoms of anxiety. The reciprocal, prospective relationship between chronotype and internalizing psychopathology is specific to depression during adolescence.

Missing a beat: assessment of circadian rhythm abnormalities in bipolar disorder in the genomic era.

Circadian rhythm abnormalities have been recognized as a central feature of bipolar disorder (BD) but a coherent biological explanation for them remains lacking. Using genetic mutation of 'clock genes', robust animal models of mania and depression have been developed that elucidate key aspects of circadian rhythms and the circadian clock-mood connection. However, translation of this knowledge into humans remains incomplete. In recent years, very large genome-wide association studies (GWAS) have been conducted and the genetic underpinnings of BD are beginning to emerge. However, these genetic studies in BD do not match well with the evidence from animal studies that implicate the circadian clock in mood regulation. Even larger GWAS have been conducted for circadian phenotypes including chronotype, rhythm amplitude, sleep duration, and insomnia. These studies have identified a diverse set of associated genes, including a minority with previously well-characterized functions in the circadian clock. Taken together, the data from recent GWAS of BD and circadian phenotypes indicate that the genetic organization of the circadian clock, both in health and in BD is complex. The findings from GWAS elucidate potentially novel circadian mechanism that may be partly distinct from those identified in animal models. Pleiotropy, epistasis and nongenetic factors may play important roles in regulating circadian rhythms, some of which may underlie circadian rhythm disturbances in BD.

Assessment of sleep and circadian rhythm disorders in the very old: the Newcastle 85+ Cohort Study.

OBJECTIVES: to examine the association between subjective and objective measures of sleep and wake and other health parameters in a cohort of the very old. DESIGN: a population-based cohort study. SETTING: primary care, North East England. PARTICIPANTS: four hundred and twenty-one men and women, aged 87-89, recruited to the Newcastle 85+ Study cohort. METHODS: sleep questionnaires were administered and sleep-wake patterns were assessed over 5-7 days with a novel wrist triaxial accelerometer. Associations between sleep measures and various health parameters, including mortality at 24 months, were examined. RESULTS: only 16% of participants perceived their sleep as severely disturbed as assessed with questionnaire responses. Wrist accelerometry showed marked variation between normal and abnormal sleep-wake cycles that did not correlate with the participants' perception of sleep. Impaired sleep-wake cycles were significantly associated with cognitive impairment, disability, depression, increased falls, body mass index and arthritis but not with any other specific disease markers and with decreased survival. CONCLUSIONS: commonly used sleep questionnaires do not differentiate well between those with objectively determined disturbance of sleep-wake cycles and those with normal cycles. Abnormal sleep-wake patterns are associated with institutionalisation, cognitive impairment, disability, depression and arthritis but not with other diseases; there is also an association with reduced survival.

Depression scores associate with chronotype and social jetlag in a rural population.

In public health, mood disorders are among the most important mental impairments. Patients with depressive episodes exhibit daily mood variations, abnormal patterns in sleep-wake behavior, and in the daily rhythms of several endocrine-metabolic parameters. Although the relationship between the sleep/circadian processes and mood disorders is poorly understood, clock-related therapies, such as light therapy, sleep deprivation, and rigid sleep schedules, have been shown to be effective treatments. Several studies investigated the relationship between circadian phenotype (chronotype) and depression. These focused mainly on urban populations and assessed diurnal preferences (Morningness-Eveningness score) rather than the actual timing of sleep and activity. Here, we used the Beck Depression Inventory (BDI) in an essentially rural population (N?=?4051), and investigated its relation to circadian phenotype (chronotype and social jetlag), assessed with the Munich Chronotype Questionnaire (MCTQ). In our study design, we (i) normalized both chronotype and BDI scores for age and sex (MSF(sas) and BDI(as), respectively); (ii) calculated individual social jetlag (misalignment of the biological and social time); and (iii) investigated the relationship between circadian phenotypes and BDI scores in a population homogeneous in respect to culture, socioeconomic factors, and daily light exposure. A 15.65% (N?=?634) of the participants showed mild to severe depressive BDI scores. Late chronotypes had a higher BDI(as) than intermediate and early types, which was independent of whether or not the participants were smokers. Both chronotype and BDI(as) correlated positively with social jetlag. BDI(as) was significantly higher in subjects with >2?h of social jetlag than in the rest of the population?again independent of smoking status. We also compared chronotype and social jetlag distributions between BDI categories (no symptoms, minimal symptoms, and mild to severe symptoms of depression) separately for men and women and for four age groups; specifically in the age group 31?40 yrs, subjects with mild to severe BDI scores were significantly later chronotypes and suffered from higher social jetlag. Our results indicate that misalignment of circadian and social time may be a risk factor for developing depression, especially in 31- to 40-yr-olds. These relationships should be further investigated in longitudinal studies to reveal if reduction of social jetlag should be part of prevention strategies. (Author correspondence: karla.allebrandt@med.uni-muenchen.de ).

Socioeconomic status, race, and diurnal cortisol decline in the Coronary Artery Risk Development in Young Adults (CARDIA) Study.

OBJECTIVES: The objectives of this study were to assess whether socioeconomic status (SES) is associated with dysregulation of the cortisol diurnal rhythm and whether this association is independent of race and occurs equally in whites and blacks; and to determine if an association between SES and cortisol can be explained (is mediated) by behavioral, social, and emotional differences across the SES gradient. METHODS: Seven hundred eighty-one subjects from a multisite sample representing both whites and blacks provided six saliva cortisol samples over the course of the day: at awakening, 45 minutes, 2.5 hours, 8 hours, and 12 hours after awakening, and at bedtime. RESULTS: Both lower SES (education and income) and being black were associated with higher evening levels of cortisol. These relationships were independent of one another and SES associations with cortisol were similar across racial categories. The evidence was consistent with poorer health practices (primarily smoking), higher levels of depressive symptoms, poorer social networks and supports, and feelings of helplessness (low mastery) mediating the link between SES and cortisol. However, we found no evidence for psychosocial or behavioral mediation of the association between race and cortisol response. CONCLUSIONS: Lower SES was associated in a graded fashion with flatter diurnal rhythms as a result of less of a decline during the evening. This association occurred independent of race and the data were consistent with mediation by health practices, emotional and social factors. Blacks also showed a flatter rhythm at the end of the day. This association was independent of SES and could not be explained by behavioral, social, or emotional mediators.