Serotonin transporter genotype, morning cortisol and subsequent depression in adolescents

Depressive symptoms during adolescence: comparison between epidemiological and high risk sampling

PURPOSE

Both epidemiological (unselected) and high risk (screening on known risk criteria) samplings have been used to investigate the course of affective disorders. Selecting individuals on multiple risk criteria may create a sample not comparable to individuals with similar risk criteria within the general population. This study compared depressive symptoms across the two sampling methods to test this possibility.

METHODS

The high risk Cambridge Hormones and Moods Project (CHAMP) screened and recruited adolescents aged 12 to 16. A total of 905 (710 high risk) individuals participated and were reassessed at three follow-ups. The ROOTS epidemiological sample consisted of 1,208 14-year-olds reassessed at 15.5 and 17 years. The risk profile for CHAMP was recreated in the ROOTS study. Both samples completed the Moods and Feelings Questionnaire, a self-report measure of current depressive symptoms.

RESULTS

Comparing individuals with the same high risk profiles across the CHAMP and ROOTS studies revealed no significant differences in mean depression scores. Combining the samples revealed that for females, mean depression scores were maintained from 12 to 15 years then declined by 17 years. For males, scores declined from 12 throughout adolescence. High risk status led to consistently higher levels of depressive symptoms in female adolescents but result in little change within male adolescents.

CONCLUSIONS

The high risk design recruited adolescents with a depression symptoms profile comparable to the general population for both sexes. High risk status may alter the trajectory of depressive symptoms in female adolescents only. Males may be less sensitive to recent adversity.

Biological indicators of illness risk in offspring of bipolar parents: targeting the hypothalamic-pituitary-adrenal axis and immune system

AIM

The study aims to provide a selective review of the literature pertaining to the hypothalamic-pituitary-adrenal (HPA) axis and immune abnormalities as informative biological indicators of vulnerability in bipolar disorder (BD).

METHOD

We summarize key findings relating to HPA axis and immunological abnormalities in bipolar patients and their high-risk offspring. Findings derive from a review of selected original papers published in the literature, and supplemented by papers identified through bibliography review. Neurobiological findings are discussed in the context of emergent BD in those at genetic risk and synthesized into a neurodevelopmental model of illness onset and progression.

RESULTS

BD is associated with a number of genetic and possibly epigenetic abnormalities associated with neurotransmitter, hormonal and immunologically mediated neurobiological pathways. Data from clinical and high-risk studies implicate HPA axis and immune system abnormalities, which may represent inherited vulnerabilities important for the transition to illness onset. Post-mortem and clinical studies implicate intracellular signal transduction processes and disturbance in energy metabolism associated with established BD. Specifically, long-standing maladaptive alterations such as changes in neuronal systems may be mediated through changes in intracellular signalling pathways, oxidative stress, cellular energy metabolism and apoptosis associated with substantial burden of illness.

CONCLUSIONS

Prospective longitudinal studies of endophenotypes and biomarkers such as HPA axis and immune abnormalities in high-risk offspring will be helpful to understand genetically mediated biological pathways associated with illness onset and progression. A clinical staging model describing emergent illness in those at genetic risk should facilitate this line of investigation.

Cortisol levels in response to starting school in children at increased risk for social phobia

BACKGROUND

Research on depression has identified hyperactivity of the HPA axis as a potential contributory factor to the intergenerational transmission of affective symptoms. This has not yet been examined in the context of social phobia. The current study compared HPA axis activity in response to a universal social stressor (starting school) in children of 2 groups of women: one with social phobia and one with no history of anxiety (comparison group). To determine specificity of effects of maternal social phobia, a third group of children were also examined whose mothers had generalised anxiety disorder (GAD).

METHOD

Children provided salivary cortisol samples in the morning, afternoon and at bedtime across 3 time-blocks surrounding the school start: a month before starting school (baseline), the first week at school (stress response), and the end of the first school term (stress recovery). Child behavioural inhibition at 14 months was assessed to explore the influence of early temperament on later stress responses.

RESULTS

All children displayed an elevation in morning and afternoon cortisol from baseline during the first week at school, which remained elevated until the end of the first term. Children in the social phobia group, however, also displayed an equivalent elevation in bedtime cortisol, which was not observed for comparison children or for children of mothers with GAD. Children in the social phobia group who were classified as 'inhibited' at 14 months displayed significantly higher afternoon cortisol levels overall.

SUMMARY

A persistent stress response to school in the morning and afternoon is typical for all children, but children of mothers with social phobia also display atypical elevations in evening cortisol levels when at school--signalling longer-term disruption of the circadian rhythm in HPA axis activity. This is the first study to report HPA axis disruption in children at increased risk of developing social phobia. Future research should determine whether this represents a pathway for symptom development, taking early temperament into account.

Childhood adversity and allostatic overload of the hypothalamic-pituitary-adrenal axis: a vulnerability model for depressive disorders

Childhood adversity is associated with increased risk for onset of depressive episodes. This review will present evidence that allostatic overload of the hypothalamic-pituitary-adrenal axis (HPAA) partially mediates this association. The HPAA is the physiological system that regulates levels of the stress hormone cortisol. First, data from animals and humans has shown that early environmental adversity is associated with long-term dysregulation of the HPAA. This may occur due to permanent epigenetic modification of the glucocorticoid receptor. Second, data from humans has demonstrated that HPAA dysregulation is associated with increased risk of future depression onset in healthy individuals, and pharmacological correction of HPAA dysregulation reduces depressive symptoms. HPAA dysregulation may result in corticoid-mediated abnormalities in neurogenesis in early life and/or neurotoxicity on neural systems that subserve emotion and cognition.

Sensitivity to stress among the offspring of parents with bipolar disorder: a study of daytime cortisol levels

BACKGROUND

It is well known that the hypothalamic-pituitary-adrenal (HPA) axis is compromised in major depression and bipolar disorder. There is increasing evidence that subtle HPA abnormalities, such as elevated cortisol levels, precede the development of an affective disorder. Interpersonal stress is also associated with the development of affective disorders. The present study sought to determine whether interpersonal chronic and episodic stress moderated the relationship between cortisol levels in the natural environment and risk status, defined as having a parent with bipolar disorder.

METHOD

Sixty-two offspring of parents with bipolar disorder (OBD) and 60 offspring with no family history of affective disorders (OFH-), aged 19.48 years (s.d.=3.38, range 14-28), completed interviews assessing mental disorders and chronic and episodic stress, and provided saliva samples over 3 days.

RESULTS

Regression analyses revealed that the OBD who experienced high interpersonal chronic stress displayed a larger cortisol rise following awakening than the OBD reporting low interpersonal chronic stress. The same relationship was also found for levels of non-interpersonal chronic stress. The OBD who reported experiencing severe interpersonal episodic stress exhibited higher levels of daytime cortisol than the OBD reporting interpersonal episodic stress of mild severity. Importantly, none of the above relationships were detected in the OFH-. Each of the interactions between family history of affective disorders and stress remained after controlling for age, gender and offspring lifetime affective disorders and current non-affective disorders.

CONCLUSIONS

A biological sensitivity to stress may underlie the susceptibility to affective disorders among the OBD.

Translational research approach to biological and modifiable risk factors of psychosis and affective disorders

OBJECTIVES

This review summarizes the literature on (molecular-) biological, medical, environmental and modifiable risk factors for psychosis and mood disorders with the view of their suitability for translational research and mental health practice from preventative and clinical treatment perspectives.

METHODS

This review summarized literature on biological, medical, environmental and modifiable risk factors for psychosis and mood disorders evaluating their potential for translational research and clinical practice.

RESULTS

Based on the concept of the gene - environment interaction in the development of mental disorders, we highlight the numerous risk factors reported to contribute to an increased susceptibility to schizophrenia and mood disorders of young adults to late-life. Special emphasis is placed onto the discussion on the requirement of translational and interdisciplinary research approaches integrating basic and clinical neuroscience approaches that may have important implications for future studies and clinical practice.

CONCLUSIONS

Interdisciplinary research approaches integrating developmental neuroscience and policy makers are encouraged in order to achieve effective prevention and intervention programs addressing environmental, behavioural, biological factors relevant to psychiatric disorders during young ages, adulthood and aging.

Translational epidemiology in psychiatry: linking population to clinical and basic sciences

Translational research generally refers to the application of knowledge generated by advances in basic sciences research translated into new approaches for diagnosis, prevention, and treatment of disease. This direction is called bench-to-bedside. Psychiatry has similarly emphasized the basic sciences as the starting point of translational research. This article introduces the term translational epidemiology for psychiatry research as a bidirectional concept in which the knowledge generated from the bedside or the population can also be translated to the benches of laboratory science. Epidemiologic studies are primarily observational but can generate representative samples, novel designs, and hypotheses that can be translated into more tractable experimental approaches in the clinical and basic sciences. This bedside-to-bench concept has not been explicated in psychiatry, although there are an increasing number of examples in the research literature. This article describes selected epidemiologic designs, providing examples and opportunities for translational research from community surveys and prospective, birth cohort, and family-based designs. Rapid developments in informatics, emphases on large sample collection for genetic and biomarker studies, and interest in personalized medicine--which requires information on relative and absolute risk factors--make this topic timely. The approach described has implications for providing fresh metaphors to communicate complex issues in interdisciplinary collaborations and for training in epidemiology and other sciences in psychiatry.

Elevated daytime cortisol levels: a biomarker of subsequent major affective disorder?

BACKGROUND

Several studies have reported that the offspring of parents with affective disorders secrete high levels of daytime cortisol. A few studies have shown that high cortisol levels preceded the onset of affective symptoms. Only one study to date has found that an elevation in cortisol preceded the onset of an affective disorder, but this was observed only in those youth carrying the short allele of the serotonin transporter gene promoter polymorphism (Goodyer et al., 2009).

METHODS

We followed 28 offspring of parents with bipolar disorder and 31 offspring of parents with no affective disorder from an average age of 17.5years to an average age of 20.0years to determine if cortisol levels at baseline predicted the subsequent development of an affective disorder. At baseline and at follow-up participants completed a diagnostic assessment, and at baseline they provided saliva samples. Daytime cortisol levels were computed as the mean of eight to 24 samples measured across two to six days.

RESULTS

Among the 59 participants, cortisol levels at the mean age of 17.5years predicted the development of an affective disorder during the subsequent 2.5year (odds ratio: 2.1, 95% confidence interval=1.0-4.1, p<0.05) after controlling for offspring mental disorders at the first assessment and having a parent with bipolar disorder.

LIMITATIONS

The findings should be interpreted with caution, as the sample size was small.

CONCLUSION

Elevated daytime cortisol levels in late adolescence may be a biomarker of vulnerability for affective disorders.

Physical Activity Awareness of British Adolescents

OBJECTIVE

To assess adolescent PA awareness and investigate associations with biological and psychosocial factors.

DESIGN

Cross-sectional from November 2005 to July 2007 (ROOTS study).

SETTING

Population-based sample recruited via Cambridgeshire and Suffolk schools (UK).

PARTICIPANTS

N=799 (44% male, 14.5±0.5 years).

MAIN EXPOSURES

Self-rated PA perception, self-reported psychosocial factors, measured anthropometry.

OUTCOME MEASURE

PA measured using accelerometry over five days. 'Inactive' defined as accelerometry-measured <60 min/day of at least moderate PA (MVPA). Associations between awareness (agreement between self-rated and accelerometry-measured active/inactive) and potential correlates investigated using multinomial logistic regression.

RESULTS

70% of adolescents were inactive (81% of girls, 56% of boys, OR(95% CI) 3.41(2.41, 4.82)). 53% of all girls (63% of inactive girls) and 34% of all boys (60% of inactive boys) inaccurately rated themselves as active (over-estimators). Compared to girls accurately describing themselves as inactive (29%), girl over-estimators had lower fat mass (OR(95% CI) 0.84(0.70, 0.99)), higher SES (high vs. low 2.4(1.07, 5.32)), reported more parent-support (1.57(1.12, 2.22)) and better family relationships (0.25(0.09, 0.67)). Amongst boys accurately describing themselves as inactive (22%), over-estimators had lower fat mass (0.86(0.77, 0.96)) reported more peer-support (1.75(1.32, 2.30)) and less teasing (0.75(0.61, 0.92)).

CONCLUSIONS

A substantial number of adolescents believe themselves to be more physically active than they really are. They maybe unaware of potential health risks, and may be unlikely to participate in PA promotion programs. Increasing information of PA health benefits beyond weight control might help encourage behavior change.

From predisposition to illness: genetically sensitive intermediate pathways to mood disorders

The contemporary model of mood disorders proposes that multiple susceptibility genes interact with multiple other risk factors. However, the specific nature of the genetic vulnerability and the intermediate causal pathways are not known. In this edition of the Journal, Goodyer and colleagues report new findings suggesting genetic moderation of an association between elevated cortisol and depression in high-risk adolescents.

Polymorphisms in BDNF (Val66Met) and 5-HTTLPR, morning cortisol and subsequent depression in at-risk adolescents

BACKGROUND

There is increasing evidence for genetic effects on the hypothalamic-pituitary axis system. More than one gene is likely to moderate corticoid-mediated activity.

AIMS

To investigate whether the brain-derived neurotrophic factor (BDNF) polymorphism (rs6265, Val66Met) is associated with morning waking salivary cortisol and moderates the corticoid-mediated risk for subsequent depressive episode onset independently of the known effects of 5-HTTLPR (the serotonin transporter gene promoter).

METHOD

High-risk adolescents (n = 401) were genotyped for Val66Met BDNF and 5-HTTLPR. Salivary samples were obtained on four consecutive school days within 1 h of waking. There were 365 (91%) remaining participants reassessed at 12 months for episodes of psychiatric disorder in the follow-up period. Of these, 357 (89%) had complete data for multivariate modelling.

RESULTS

There were 41 (11.2%) individuals who reported a new episode of clinical depression over the follow-up period. Increased risk for subsequent depression was found in carriers of the Val66Val genotype in BDNF with higher morning waking cortisol. This remained present when the known interaction between carriers of a short allele of 5-HTTLPR with higher morning salivary cortisol was taken into account.

CONCLUSIONS

Both BDNF and 5-HTTLPR genes show evidence of modifying the risk of a subsequent new depressive episode associated with elevated morning salivary cortisol. In adolescents morning salivary cortisol levels may constitute a biomarker for some forms of unipolar depression.

Life course perspectives on the epidemiology of depression

Life course epidemiology seeks to understand how determinants of health and disease interact across the span of a human life, and has made significant contributions to understanding etiological mechanisms in many chronic diseases, including schizophrenia. The life course approach is ideal for understanding depression: causation in depression appears to be multifactorial, including interactions between genes and stressful events, or between early life trauma and later stress in life; timing of onset and remission of depression varies widely, indicating differing trajectories of symptoms over long periods of time, with possible differing causes and differing outcomes; and early life events and development appear to be important risk factors for depression, including exposure to acute and chronic stress in the first years of life. To better understand etiology and outcome of depression, future research must move beyond basic epidemiologic techniques that link specific exposures to specific outcomes and embrace life course principles and methods. Time-sensitive modelling techniques that are able to incorporate multiple interacting factors across long periods of time, such as structural equation models, will be critical in understanding the complexity of causal and influencing factors from early development to the end stages of life. Using these models to identify key pathways that influence trajectories of depression across the life course will help guide prevention and intervention.

Genetics of childhood and adolescent depression: insights into etiological heterogeneity and challenges for future genomic research

There is heterogeneity between depression in childhood, adolescence and adulthood in terms of the gender composition of affected cases, prevalence, rates of recurrence and risk factors. This raises complex questions for refining the phenotype for molecular genetic studies of depression and the selection of appropriate proband groups. This article aims to provide a review of issues arising from family, twin and adoption studies of relevance to molecular genetic studies, and to summarize molecular genetic findings on childhood/adolescent depression. While retrospective studies of adults suggest greater familial aggregation among those with an earlier age of onset, prospective studies do not confirm this association. In fact, taken together, evidence from family and twin studies suggests that prepubertal depression is more strongly associated with psychosocial adversity, is less heritable and shows lower levels of continuity with adult depression than either adolescent or adult depression. Adolescent depressive symptoms and disorder show similar levels of heritability to depression in adult life, although there is only one twin study of adolescent depressive disorder, and heritability estimates of depressive symptoms vary widely between studies. This variability in heritability estimates is partly attributable to age and informant effects. Adoption studies and other intergenerational transmission designs show that the transmission of depression between parents and children involves genetic and environmental processes, with converging evidence that environmental processes are most important. Molecular genetic studies of childhood/adolescent depression have to date used a candidate gene approach and focused on genes already examined in adult studies. Prospective longitudinal studies of community and high-risk samples are needed to clarify issues of etiological heterogeneity in depression, and these should in turn inform the planning of molecular genetic studies.

Glucagon-like peptide-1 receptor gene polymorphism (Leu260Phe) is associated with morning cortisol in preschoolers

Glucagon-like peptide-1 (GLP-1) has been shown to be a potent stress-regulating neuropeptide in animal models, but little is known about whether genetic polymorphisms that influence this peptide influence stress responses in humans. We therefore explored whether a missense mutation (rs1042044) in the GLP-1 receptor was associated with morning and evening salivary cortisol levels in preschool aged children. Morning and evening saliva samples and individual buccal swabs for DNA extraction were collected from seventy-seven preschool aged children. Salivary cortisol was assayed using a time-resolved fluorescence immunoassay with fluorometric end-point detection (DELFIA), and the rs1042044 single nucleotide polymorphism (SNP) was genotyped using allele specific TaqMan probes. Children homozygous for the phenylalanine (C) substitution in the GLP-1R gene had significantly higher morning salivary cortisol levels than children with other GLP-1R genotypes (p=0.029). Additionally, children with one or two copies of the phenylalanine (C) allele had significantly higher morning cortisol levels compared to children homozygous for the leucine (A) allele (p=0.008). Our results identify associations between a novel genetic variant of GLP-1R and hypothalamus-pituitary-adrenal (HPA) axis regulation. This polymorphism may have functional significance in stress-related psychiatric disorders.

Leaving care and mental health: outcomes for children in out-of-home care during the transition to adulthood

There were 59,500 Children in out-of-home care in England in 2008. Research into this population points to poor health and quality of life outcomes over the transition to adult independence. This undesirable outcome applies to mental health, education and employment. This lack of wellbeing for the individual is a burden for health and social care services, suggesting limitations in the current policy approaches regarding the transitional pathway from care to adult independence. Although the precise reasons for these poor outcomes are unclear long term outcomes from national birth cohorts suggest that mental health could be a key predictor for subsequent psychosocial adjustment.Researching the wellbeing of children in out-of-home care has proven difficult due to the range and complexity of the factors leading to being placed in care and the different methods used internationally for recording information. This paper delineates the estimated prevalence of mental health problems for adolescents in the care system, organisational factors, influencing service provision, and pathways through the transition from adolescence to independent young adult life. The extent to which being taken into care as a child moderates adult wellbeing outcomes remains unknown. Whether the care system enhances, reduces or has a null effect on wellbeing and specifically mental health cannot be determined from the current literature. Nonetheless a substantial proportion of young people display resilience and experience successful quality of life outcomes including mental capital. A current and retrospective study of young people transitioning to adult life is proposed to identify factors that have promoted successful outcomes and which would be used to inform policy developments and future longitudinal studies.

Leaving care and mental health: outcomes for children in out-of-home care during the transition to adulthood

There were 59,500 Children in out-of-home care in England in 2008. Research into this population points to poor health and quality of life outcomes over the transition to adult independence. This undesirable outcome applies to mental health, education and employment. This lack of wellbeing for the individual is a burden for health and social care services, suggesting limitations in the current policy approaches regarding the transitional pathway from care to adult independence. Although the precise reasons for these poor outcomes are unclear long term outcomes from national birth cohorts suggest that mental health could be a key predictor for subsequent psychosocial adjustment.Researching the wellbeing of children in out-of-home care has proven difficult due to the range and complexity of the factors leading to being placed in care and the different methods used internationally for recording information. This paper delineates the estimated prevalence of mental health problems for adolescents in the care system, organisational factors, influencing service provision, and pathways through the transition from adolescence to independent young adult life. The extent to which being taken into care as a child moderates adult wellbeing outcomes remains unknown. Whether the care system enhances, reduces or has a null effect on wellbeing and specifically mental health cannot be determined from the current literature. Nonetheless a substantial proportion of young people display resilience and experience successful quality of life outcomes including mental capital. A current and retrospective study of young people transitioning to adult life is proposed to identify factors that have promoted successful outcomes and which would be used to inform policy developments and future longitudinal studies.

The early stages of bipolar disorder and recent developments in the understanding of its neurobiology

Bipolar disorder is a severe recurrent psychiatric illness that often manifests in adolescence, a time of marked neurobiological change. The current model is one of multiple susceptibility genes interacting with other risk factors leading to alterations in the normal maturational trajectory of the CNS. Longitudinal studies of children of affected parents has enabled mapping of the early natural history of bipolar disorder. Convergent evidence from longitudinal high-risk studies suggest that bipolar disorder evolves in a series of clinical stages from nonspecific childhood disorders to depressive disorders in early adolescence and bipolar spectrum disorders in later adolescence and adulthood. At present, genetic studies and research into specific biological markers in bipolar patients and their family members are underway. Advances in understanding the neurobiological underpinnings of bipolar disorder will require addressing etiological heterogeneity of bipolar disorder and refining the phenotypic definition. In the latter case, the staging model may be a helpful organizing framework.

Borderline personality disorder: hypothalamus pituitary adrenal axis and findings from neuroimaging studies

Borderline personality disorder (BPD) is a complex and serious mental disorder that is commonly seen psychiatric practice. Although stress, especially early life stress, seems to be associated with the development of the disorder, there has been far less research on the function of the hypothalamic-pituitary-adrenal (HPA) axis in BPD, compared to other psychiatric disorders, such as major depressive disorder and post-traumatic stress disorder. Stress has been suggested to exert damaging effects on the brain, particularly the hippocampus; therefore, neuroimaging studies yield important insight into the neurobiology of BPD. This article reviews research on the HPA axis and neuroimaging studies in BPD and aims to integrate these findings.

Preadolescents' somatic and cognitive-affective depressive symptoms are differentially related to cardiac autonomic function and cortisol: the TRAILS study

OBJECTIVE

To examine in a nonclinical sample of preadolescents the possibility that somatic and cognitive-affective depressive symptoms are differentially related with the autonomic nervous system (ANS) and the hypothalamic-pituitary-adrenal (HPA) axis. Depression is a well-known risk factor for cardiovascular disease and mortality. Dysregulation of the ANS and the HPA axis have been proposed as underlying mechanisms. Several studies suggest that only a subset of the depression symptoms account for associations with cardiovascular prognosis.

METHODS

Self-reported somatic and cognitive-affective depressive symptoms were examined in relationship to heart rate variability (HRV), spontaneous baroreflex sensitivity (BRS), and the cortisol awakening response (CAR) in 2049 preadolescents (mean age = 11.1 years; 50.7% = girls) from the Tracking Adolescents' Individual Lives Survey (TRAILS).

RESULTS

Physiological measurements were not associated with the overall measure of depressive symptoms. Somatic depressive symptoms were negatively related to HRV and BRS, and positively to the CAR; cognitive-affective depressive symptoms were positively related to HRV and BRS, and negatively to the CAR. Associations with the CAR pertained to boys only.

CONCLUSIONS

Somatic and cognitive-affective depressive symptoms differ in their association with both cardiac autonomic and HPA axis function in preadolescents. Particularly, somatic depression symptoms may mark cardiac risk.