Sanne H. Booij

Chronicity of depressive problems and the cortisol response to psychosocial stress in adolescents: The TRAILS study

Clinical and epidemiological studies, further supported by meta-analytic studies, indicate a possible association between chronicity (i.e., persistence or recurrence) of depression and hypothalamic-pituitary-adrenal (HPA) axis responsiveness to psychosocial stress. In the present study, we examined whether and how chronicity of depressive problems predicts cortisol responses to a standardized social stress test in adolescents. Data were collected in a high-risk focus sample (n=351) of the Tracking Adolescents Individual Lives Survey (TRAILS) cohort, a large prospective population study with bi- to triennial measurements. Depressive problems were assessed around age 11, 13.5, and 16. Cortisol levels were measured in saliva, sampled before, during, and after the Groningen Social Stress Test (GSST), to determine the cortisol response to psychosocial stress. The area under the curve with respect to the increase (AUCi) (i.e., change from baseline) of the cortisol response was used as a measure of HPA axis response. By means of linear regression analysis and repeated-measures analysis of variance, it was examined whether chronicity of depressive problems predicted the cortisol response to the GSST around the age of 16. Chronicity of depressive problems was significantly associated with cortisol stress responses. The relationship was curvilinear, with recent-onset depressive problems predicting an increased cortisol response, and more chronic depressive problems a blunted response. The results of this study suggest that depressive problems initially increase cortisol responses to stress, but that this pattern reverses when depressive problems persist over prolonged periods of time.

Intra- and inter-individual variability of longitudinal daytime melatonin secretion patterns in depressed and non-depressed individuals

Disrupted melatonin secretion is regarded as a link between circadian rhythm and major depression, but results have been contradictory. We hypothesize that this might be due to averaging across individuals and too short measurements periods. In this study, pair-matched depressed and non-depressed individuals sampled their saliva three times a day, 30 days, in their natural environment. The depressed group showed significantly more variance and higher melatonin levels (pu2009<u20090.05). Substantial interindividual heterogeneity and day-to-day variability was found. The individual time-series approach allowed us to reveal this variability. Important information remains unnoticed when analyzing melatonin only at the group level.

Cortisol and α-Amylase Secretion Patterns between and within Depressed and Non-Depressed Individuals

Objectives Associations between biological stress markers and depression are inconsistent across studies. We assessed whether inter- and intra-individual variability explain these inconsistencies. Methods Pair-matched depressed and non-depressed participants (N = 30) collected saliva thrice a day for 30 days, resulting in 90 measurements per individual. The relationships between measures of stress-system function and depression were examined at the group level by means of mixed model analyses, and at the individual level by means of pair-matched comparisons. The analyses were repeated after adjusting for time-varying lifestyle factors by means of time-series regression analyses. Results Cortisol and α-amylase levels were higher, the α-amylase/cortisol ratio larger, and the daily cortisol slope steeper in the depressed compared to the non-depressed group. Adjusting for lifestyle factors and antidepressant use reduced the associations under study. In 40%–60% of the matched comparisons, depressed individuals had higher cortisol and α-amylase levels, a larger α-amylase/cortisol ratio, and a steeper daily slope than their non-depressed match, regardless of adjustment. Conclusions Our group-level findings were mostly in line with the literature but generalization to individuals appeared troublesome. Findings of studies on this topic should be interpreted with care, because in clinical practice the focus is on individuals instead of groups.

Change in daily life behaviors and depression : Within-person and between-person associations

OBJECTIVEnThis study examined associations between daily physical, sedentary, social, and leisure behaviors and depressive symptoms (a) at a macrolevel, over the course of an Experience Sampling (ESM) self-monitoring intervention, and (b) at a microlevel, by examining daily within-person associations. Second, we examined the effects of the ESM self-monitoring intervention on these daily life behaviors.nnnMETHODSnIndividuals with a diagnosis of depression (N = 102) receiving pharmacological treatment were randomized to 1 of 2 six-week ESM intervention conditions or a control condition. Physical, sedentary, social, and leisure behaviors as well as depressive symptoms were assessed prospectively in every-day life at baseline, postintervention, and during the ESM interventions.nnnRESULTSnChange in physical activity and talking from baseline to postintervention was associated with change in depressive symptoms from baseline to postintervention. Within-person daily fluctuations in talking, physical activity, doing nothing/resting, and being alone predicted end-of-day depressive symptoms over and above depressive symptoms at the previous day. The ESM interventions contributed to change in talking, doing nothing/resting, and being alone over time in comparison with the control group. The analyses revealed individual differences in the amount of behavioral change over time and in the within-subject associations between daily behaviors and depressive symptoms.nnnCONCLUSIONSnThe findings suggest that physical, sedentary, and social behaviors have affective implications for daily mental health of individuals with depression. Self-monitoring using ESM may be a useful add-on tool to achieve behavioral change and to gain personalized insight in behaviors that improve daily depressive symptoms.

How to assess stress biomarkers for idiographic research

Associations between stress-related biomarkers, like cortisol or catecholamines, and somatic or psychological symptoms have often been examined at the group level. Studies using this nomothetic approach reported equivocal findings, which may be due to high levels of intra-individual variance of stress biomarkers. More importantly, analyses at the group level provide information about the average patient, but do not necessarily have meaning for individual patients. An alternative approach is to examine data at the level of individual patients in so-called idiographic research. This method allows identifying individuals in whom symptoms are explained by preceding alterations in specific stress biomarkers, based on time series of symptoms and stress biomarkers. To create time series of sufficient length for statistical analysis, many subsequent stress biomarker measurements are needed for each participant. In the current paper, different matrices (i.e. saliva, urine, nail and hair) are discussed in light of their applicability for idiographic research. This innovative approach might lead to promising new insights in the association between stress biomarkers and psychological or somatic symptoms. New collection tools for stress biomarkers, like the use of sweat pads, automated microdialysis systems, dried blood spots, or smartphone applications, might contribute to the feasibility and implementation of idiographic research in the future.

Markers of stress and inflammation as potential mediators of the relationship between exercise and depressive symptoms: Findings from the TRAILS study

The hypothalamic-pituitary-adrenal axis, autonomic nervous system, and immune system have been proposed to underlie the antidepressant effect of exercise. Using a population sample of 715 adolescents, we examined whether pathways from exercise to affective and somatic symptoms of depression were mediated by these putative mechanisms. Exercise (hours/week) and depressive symptoms were assessed at age 13.5 (±u20090.5) and 16.1 (±u20090.6). Cortisol and heart rate responses to a standardized social stress test and C-reactive protein levels were measured at age 16. Exercise was prospectively and inversely related to affective (Bu2009=u2009-0.16, 95% CIu2009=u2009-0.30 to -0.03) but not somatic symptoms (Bu2009=u2009-0.04, 95% CIu2009=u2009-0.21 to 0.13). Heart rate during social stress partially mediated this relationship (Bu2009=u2009-0.03, 95% CIu2009=u2009-0.07 to -0.01). No other mediating effects were found. Hence, the autonomic stress system may play a role in the relationship between exercise and depressive symptoms.

Temporal dynamics of physical activity and affect in depressed and nondepressed individuals.

OBJECTIVEnThe association between physical activity and affect found in longitudinal observational studies is generally small to moderate. It is unknown how this association generalizes to individuals. The aim of the present study was to investigate interindividual differences in the bidirectional dynamic relationship between physical activity and affect, in depressed and nondepressed individuals, using time-series analysis.nnnMETHODnA pair-matched sample of 10 depressed and 10 nondepressed participants (mean age = 36.6, SD = 8.9, 30% males) wore accelerometers and completed electronic questionnaires 3 times a day for 30 days. Physical activity was operationalized as the total energy expenditure (EE) per day segment (i.e., 6 hr). The multivariate time series (T = 90) of every individual were analyzed using vector autoregressive modeling (VAR), with the aim to assess direct as well as lagged (i.e., over 1 day) effects of EE on positive and negative affect, and vice versa.nnnRESULTSnLarge interindividual differences in the strength, direction and temporal aspects of the relationship between physical activity and positive and negative affect were observed. An exception was the direct (but not the lagged) effect of physical activity on positive affect, which was positive in nearly all individuals.nnnCONCLUSIONnThis study showed that the association between physical activity and affect varied considerably across individuals. Thus, while at the group level the effect of physical activity on affect may be small, in some individuals the effect may be clinically relevant.

The temporal dynamics of cortisol and affective states in depressed and non-depressed individuals

OBJECTIVESnCortisol levels have been related to mood disorders at the group level, but not much is known about how cortisol relates to affective states within individuals over time. We examined the temporal dynamics of cortisol and affective states in depressed and non-depressed individuals in daily life. Specifically, we addressed the direction and timing of the effects, as well as individual differences.nnnMETHODSnThirty depressed and non-depressed participants (aged 20-50 years) filled out questionnaires regarding their affect and sampled saliva three times a day for 30 days in their natural environment. They were pair-matched on age, gender, smoking behavior and body mass index. The multivariate time series (T=90) of every participant were analyzed using vector autoregressive (VAR) modeling to assess lagged effects of cortisol on affect, and vice versa. Contemporaneous effects were assessed using the residuals of the VAR models. Impulse response function analysis was used to examine the timing of effects.nnnRESULTSnFor 29 out of 30 participants, a VAR model could be constructed. A significant relationship between cortisol and positive or negative affect was found for the majority of the participants, but the direction, sign, and timing of the relationship varied among individuals.nnnCONCLUSIONnThis approach proves to be a valuable addition to traditional group designs, because our results showed that daily life fluctuations in cortisol can influence affective states, and vice versa, but not in all individuals and in varying ways. Future studies may examine whether these individual differences relate to susceptibility for or progression of mood disorders.

Affective reactivity to daily life stress: Relationship to positive psychotic and depressive symptoms in a general population sample

INTRODUCTIONnIncreased affective reactivity to daily life stress has been found in individuals with psychosis and depression, and in those at risk for these conditions. Because depressive and psychotic symptoms often co-occur, increased affective reactivity in these disorders may be explained by the presence of depressive symptoms, psychotic symptoms, or both. Therefore, we examined whether affective reactivity to daily stress is related to positive psychotic symptoms, independently of depressive symptoms, and vice versa.nnnMETHODSnWe used data from an intensive sampling study in the general population (n = 411), with three measurements a day (t = 90). The following subjective stressors were assessed: appraisal of activities, appraisal of social interactions, and experienced physical discomfort. Affective reactivity was conceptualized as both the positive affect (PA) and negative affect (NA) response to these stressors. By means of mixed model analyses, it was examined whether affective reactivity was independently related to depressive and/or positive psychotic symptoms.nnnRESULTSnThe PA response to activities and NA response to social interactions were negatively and positively related to depressive symptoms, respectively, independent of psychotic symptoms. In contrast, no (in)dependent association was found between positive psychotic symptoms and affective reactivity to any of the daily life stressors. These findings were confirmed in a subsample with increased symptoms.nnnLIMITATIONSnThe prevalence of positive psychotic symptoms was relatively low in this general population sample.nnnCONCLUSIONSnIncreased affect reactivity predicts depressive symptoms, but not positive psychotic symptoms. Affective reactivity may still facilitate the development of psychotic symptomatology via its impact on depressive symptoms.

Dimensional and discrete variations on the psychosis continuum in a Dutch crowd-sourcing population sample

BACKGROUNDnMild psychotic experiences are common in the general population. Although transient and benign in most cases, these experiences are predictive of later mental health problems for a significant minority. The goal of the present study was to perform examinations of the dimensional and discrete variations in individuals reporting of subclinical positive and negative psychotic experiences in a unique Dutch internet-based sample from the general population.nnnMETHODSnPositive and negative subclinical psychotic experiences were measured with the Community Assessment of Psychic Experiences in 2870 individuals. First, the prevalence of these experiences and their associations with demographics, affect, psychopathology and quality of life were investigated. Next, latent class analysis was used to identify data-driven subgroups with different symptom patterns, which were subsequently compared on aforementioned variables.nnnRESULTSnSubclinical psychotic experiences were commonly reported. Both positive and negative psychotic experiences were associated with younger age, more negative affect, anxiety and depression as well as less positive affect and poorer quality of life. Seven latent classes (Low psychotic experiences, Lethargic, Blunted, Distressed, Paranormal, Distressed/grandiose and Distressed/positive psychotic experiences) were identified that demonstrated both dimensional differences in the number/severity of psychotic experiences and discrete differences in the patterns of reported experiences.nnnCONCLUSIONnSubclinical psychotic experiences show both dimensional severity variations and discrete symptom-pattern variations across individuals. To understand and capture all interindividual variations in subclinical psychotic experiences, their number, nature and context (co-occurrence patterns) should be considered at the same time. Only some psychotic experiences may lay on a true psychopathological psychosis continuum.