Early risk factors for adult bipolar disorder in adolescents with mood disorders: a 15-year follow-up of a community sample

Exploring the effects of family and life events on genetic and environmental architecture of schizotypal and hypomanic dimensions: Insights from a twin study

BACKGROUND

Strategies of prevention for psychiatric disorders need a deep understanding of the aetiological factors involved in the psychopathological processes. Our twin study aims at disentangling the contributions of genes and environment to schizotypal and hypomanic dimensions, considering the role of stressful life events (LEs) and the quality of family relationships.

METHODS

The Magical Ideation Scale (MIS) and Perceptual Aberration Scale (PAS) were used to assess positive schizotypy, while Hypomanic Personality Scale (HPS) and its sub-scales were used to investigate proneness to affective disorders. 268 twins (54.5 % female; aged 18.0 ± 6.68) were included. Participants filled out a questionnaire on LEs and their parents provided an evaluation of intra-family relationship (Relationship Quality Index, RQI). Classic univariate twin models for quantitative traits were fitted for scales, and the effects of covariates (LEs and RQI) were assessed.

RESULTS

For MIS, HPS and its sub-scales, significant common and unique environmental effects were detected, with genetic factors affecting only HPS Social Vitality sub-scale. Unique environment was the only source of variance of PAS score. The number of recent LEs influenced MIS and PAS models, while RQI score affected MIS model.

LIMITATIONS

The main limitation of the study is the small sample size, which reduces statistical power and may potentially lead to an underestimation of heritability. Additionally, the cross-sectional design limits the possibility to draw causal considerations.

CONCLUSIONS

Findings provide preliminary evidence for a significant environmental role in modulating states of vulnerability. Moreover, the expression of positive schizotypy resulted influenced by recent stressors and intra-family relationships.

Alterations of functional connectivity in young people with depression mediate the relationship between sleep quality and cognitive function

BACKGROUND

Sleep disturbances is common in young people with depression, and poor sleep quality affects the ability to learn. In this study, we examined possible resting-state functional connectivity abnormalities between regions of interest, and clarified the relationship with depressive symptoms, sleep quality, and cognitive function.

METHODS

Resting-state functional magnetic resonance imaging (fMRI) was collected on 42 healthy controls (HCs), 82 youth depressive patients (44 without sleep disturbances (NSD), and 38 with sleep disturbances (SD)). Regions of interest were defined by using Brainnetome Atlas. Functional connectivity was calculated, and its associations with depressive symptoms, sleep quality, and cognitive function were examined using correlation analysis and mediation analysis.

RESULTS

The left and right caudal of cingulate gyrus, tongue and larynx region of postcentral gyrus were significant brain regions in NSD versus SD. The average functional connectivity between these regions was associated with poor sleep quality (r = 0.368, p = 0.001) and worse working memory (r = -0.256, p = 0.023) and mediated the relationship between sleep quality and working memory (c = -0.738, c' = -0.500).

LIMITATION

Data consistency in this study was not good enough. This study did not monitor sleep rhythms to provide objective sleep-related data.

CONCLUSION

The functional connectivity between the left and right caudal of cingulate gyrus with tongue and larynx region of postcentral gyrus may be the neural mechanism by which sleep disturbances affect working memory. This provides an intervention target for clinically improving cognitive function in young people with depression.

Lipid Biomarker Research in Bipolar Disorder: A Scoping Review of Trends, Challenges, and Future Directions

Bipolar disorder (BD) is a disabling disorder with heterogeneous symptom profiles and trajectories. Like many other neuropsychiatric disorders, clinical decision making related to diagnoses and choice of treatment is based on clinical assessments alone, and risk prediction for treatment success or resistance at an individual level remains sparse. An enormous effort to add biological markers to this risk prediction is ongoing. The role of lipids in normal brain functioning is well established, and several hypotheses about the role of lipids in the pathogenesis of neuropsychiatric disorders, including BD, have been made. The frequent comorbidity between neuropsychiatric disorders and cardiovascular disease, the genetic overlap of risk genes for severe mental disorders and genes involved in lipid regulation, and the lipid-altering effects of antipsychotics and mood stabilizers indicate that lipids could hold promise as biomarkers for neuropsychiatric disorders, including BD. To date, reviews of lipid biomarkers in schizophrenia and major depression have noted caveats for future investigations, while reviews of lipid biomarker research in BD is missing. In the current scoping review, we present a comprehensive overview of trends in previous research on lipid biomarkers in BD. The current literature varies greatly in the phenotypes investigated and study designs, leading to divergent findings. Small sample size; potential confounders related to physical activity, nutritional status, and medication use; and cross-sectional designs were frequently reported limitations. Future research may benefit from pivoting toward utilization of newer laboratory techniques such as lipidomics, but consistent use of study methods across cohorts is also needed.

Child and adolescent anxiety as a risk factor for bipolar disorder: A systematic review of longitudinal studies

OBJECTIVES

Several studies have suggested that anxiety disorders in childhood and adolescence often precede the onset of bipolar disorder. We therefore systematically reviewed the relationship between child and adolescent anxiety and later bipolar disorder.

METHODS

Online databases (Medline [for Ovid], EMBASE and PsychINFO) were searched for original, peer-reviewed studies examining the relationship between child and adolescent anxiety and later bipolar disorder. Studies in both community samples and bipolar offspring samples were included.

RESULTS

A total of 16 studies were included in the review. The results were broadly consistent and revealed that child and adolescent anxiety disorders are associated with later bipolar disorder in community samples. In bipolar offspring, child and adolescent anxiety disorders are a marker of increased risk and predict the onset of bipolar disorder and other major mood disorders.

CONCLUSIONS

There is evidence that anxiety disorders in childhood and adolescence increase the risk of later bipolar disorder. Anxiety disorders may be a useful target for early intervention in those at high-risk of bipolar disorder.

Risk of conversion to bipolar disorder in patients with late-onset major depression

To evaluate the impact of age at onset on late-life depression course and on risk of conversion to bipolar disorder (BD). A retrospective chart review of 100 elderly patients (age ≥ 65 years) diagnosed with a moderate-to-severe depressive episode and followed up for at least 18 months was conducted. Among patients affected by major depressive disorder ( N = 57), follow-up morbidity differences between those with typical onset depression (TOD) (<60 years) and those with late-onset depression (LOD) (≥60 years) were investigated using Wilcoxon rank-sum test and Cox proportional hazard model. Patients belonging to the LOD group had a significantly lower percentage of follow-up time spent with depressive symptoms compared with patients with TOD ( r = 0.36; P = 0.006), but significantly more time spent with (hypo)manic episodes ( r = -0.31; P = 0.021). Moreover, LOD was significantly associated with a faster conversion to BD (hazard ratio = 3.05; P = 0.037). Depression first emerging in late life may represent an unstable condition with a high risk to convert to BD. Given the potential clinical implications, further studies on the course of LOD are required.

Valproate Adjuvant Cognitive Behavioral Therapy in Panic Disorder Patients With Comorbid Bipolar Disorder: Case Series and Review of the Literature

Anxiety disorders are the most common comorbid psychiatric disorders in patients with bipolar disorder. Managing anxiety symptoms in comorbid conditions is challenging and has received little research interest. The findings from preclinical research on fear conditioning, an animal model of anxiety disorder, have suggested that memory reconsolidation updating (exposure-based therapy) combined with valproate might facilitate the amelioration of fear memories. Here, three cases of successful amelioration of agoraphobia and panic symptoms through valproate adjuvant therapy for cognitive behavioral therapy in patients who failed to respond to two to three consecutive standard pharmacotherapy trials over several years are described. To the best of the author's knowledge, this is the first attempt to combine CBT with valproate in patients with panic disorder, agoraphobia, and comorbid bipolar disorder. Additionally, the background preclinical research on this combination therapy based on the reconsolidation-updating mechanism, the inhibition of histone deacetylase 2, and critical period reopening, off-label use of valproate in panic disorder, plasticity-augmented psychotherapy, and how to combine valproate with CBT is discussed.

Women and ethnoracial minorities with poor cardiovascular health measures associated with a higher risk of developing mood disorder

Background

Mood disorders (MDS) are a type of mental health illness that effects millions of people in the United States. Early prediction of MDS can give providers greater opportunity to treat these disorders. We hypothesized that longitudinal cardiovascular health (CVH) measurements would be informative for MDS prediction.

Methods

To test this hypothesis, the American Heart Association’s Guideline Advantage (TGA) dataset was used, which contained longitudinal EHR from 70 outpatient clinics. The statistical analysis and machine learning models were employed to identify the associations of the MDS and the longitudinal CVH metrics and other confounding factors.

Results

Patients diagnosed with MDS consistently had a higher proportion of poor CVH compared to patients without MDS, with the largest difference between groups for Body mass index (BMI) and Smoking. Race and gender were associated with status of CVH metrics. Approximate 46% female patients with MDS had a poor hemoglobin A1C compared to 44% of those without MDS; 62% of those with MDS had poor BMI compared to 47% of those without MDS; 59% of those with MDS had poor blood pressure (BP) compared to 43% of those without MDS; and 43% of those with MDS were current smokers compared to 17% of those without MDS.

Conclusions

Women and ethnoracial minorities with poor cardiovascular health measures were associated with a higher risk of development of MDS, which indicated the high utility for using routine medical records data collected in care to improve detection and treatment for MDS among patients with poor CVH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12911-021-01674-9.

'Pediatric Bipolar Disorder' rates are still lower than claimed: a re-examination of eight epidemiological surveys used by an updated meta-analysis

Background

‘Pediatric bipolar disorder’ (PBD) is a controversial diagnosis with varying rates of clinical diagnosis. A highly cited meta-analysis (Van Meter et al. 2011) of a dozen epidemiological surveys suggested a global community prevalence of PBD of 1.8%. This was updated to 3.9% with eight additional surveys (Van Meter et al. 2019a). In terms of the Cochrane Handbook for Systematic Reviews of Interventions, the heterogenous community surveys were arguably unsuitable for statistical meta-analysis and warranted a narrative analysis. A narrative analysis (Parry et al. 2018) of the original 12 surveys concluded rates of PBD were substantially lower than 1.8% and led to a nine-article debate on the validity, arguable overdiagnosis and iatrogenic aspects of the PBD diagnosis (e.g. Carlson and Dubicka Child Adolesc Mental Health 21:86–87, 2019). This article extends the narrative analysis to include the eight newer community surveys.

Methods

A narrative analysis of the methodologies and the prevalence rates reported by the epidemiological surveys.

Results

Across all twenty surveys there was significant variation in methodologies and reported prevalence rates. Of the eight newer surveys, five (two Brazilian, one English, one Turkish, one United States) provided information of pre-adolescent prevalence rates of bipolar spectrum disorder. These pre-adolescent rates were zero or close to zero. Rates of adolescent hypomania and mania were higher, but follow-up data in two studies suggested hypomania might sometimes achieve prolonged remission or not lead to adult bipolar disorder.

Limitations

Methods in the original surveys vary and criteria used for various bipolar diagnoses were not always fully described. This limitation applies to a narrative analysis but also to a statistical meta-analysis.

Conclusion

Bipolar disorder is very rare in childhood and rare in adolescence. PBD as a diagnostic construct fails to correlate with adult bipolar disorder and the term should be abandoned. Hypomanic syndromes in adolescence may not always progress to adult bipolar disorder. Early diagnosis of bipolar disorder is important, but over-diagnosis risks adverse iatrogenic consequences.

Precursors of self-reported subclinical hypomania in adolescence: A longitudinal general population study

Symptoms of subclinical hypomania (SHM) are common in the general population of adolescents and young adults. SHM are most often transient yet might be risk markers of later bipolar disorder. The current study aimed to assess the clinical correlates of SHM at age 11 in the general population, examine the continuity of SHM from age 11-age 16 and explore the clinical precursors of age 16 SHM. As part of the Copenhagen Child Cohort 2000, 1,632 preadolescents participated in the examination of SHM and various clinical correlates at age 11, 893 were re-assessed for SHM at age 16 years. At age 11, SHM, psychotic experiences and depressive symptoms were assessed by semi-structured psychopathological interviews. Furthermore, the participants were diagnostically assessed by the Development and Well-Being Assessment and interviewed about sleep length. At age 16, SHM was assessed by self-report, using the Hypomania Checklist-32. Cannabis use occurring at age 15 or earlier was assessed at age 16. At age 11, SHM was associated with depressive disorders (Relative Risk [RR] = 2.96 [95% CI 1.26–6.96]), interview-based depressive symptoms (RR = 9.22 [5.93–14.34]), neurodevelopmental disorders (RR = 2.94 [1.66–5.20]), psychotic experiences (RR = 4.51 [2.90–7.01]) and insufficient sleep (RR = 2.10 [1.28–3.43]. In the longitudinal analyses, age 16 SHM was preceded by age 11 SHM (RR = 1.89 [1.02–3.49]), psychotic experiences (RR = 2.06, [1.28–3.33]), emotional disorders (RR = 1.77, [1.02–3.09]) and cannabis use (RR = 3.14, [1.93–5.10]), after mutual adjustment and adjustment for sex, and sociodemographic factors. In conclusion, age 11 SHM was statistically significantly associated with other types of psychopathology in cross-sectional analyses and showed some continuity with later self-reported SHM at age 16. Particularly early psychotic experiences and cannabis use stood out as independent precursors of self-reported SHM and might constitute important risk markers for the development of future SHM and bipolar disorder. An important potential caveat of the current study includes the self-report assessment of SHM.

Psychopathological precursors of the onset of mood disorders in offspring of parents with and without mood disorders: results of a 13-year prospective cohort high-risk study

BACKGROUND

There is still limited evidence from prospective high-risk research on the evolution of specific disorders that may emerge early in the development of mood disorders. Moreover, few studies have examined the specificity of mood disorder subtypes among offspring of parents with both major subtypes of mood disorders and controls based on prospective tracking across the transition from childhood to adulthood. Our specific objectives were to (a) identify differences in patterns of psychopathological precursors among youth with (hypo)mania compared to MDD and (b) examine whether these patterns differ by subtypes of parental mood disorders.

METHODS

Our data stem from a prospective cohort study of 449 directly interviewed offspring (51% female, mean age 10.1 years at study intake) of 88 patients with BPD, 71 with MDD, 30 with substance use disorders and 60 medical controls. The mean duration of follow-up was 13.2 years with evaluations conducted every three years.

RESULTS

Within the whole cohort of offspring, MDE (Hazard Ratio = 4.44; 95%CI: 2.19-9.02), CD (HR = 3.31;1.55-7.07) and DUD (HR = 2.54; 1.15-5.59) predicted the onset of (hypo)manic episodes, whereas MDD in offspring was predicted by SAD (HR = 1.53; 1.09-2.15), generalized anxiety (HR = 2.56; 1.05-6.24), and panic disorder (HR = 3.13; 1.06-9.23). The early predictors of (hypo)mania in the whole cohort were also significantly associated with the onset of (hypo)mania among the offspring of parents with BPD.

CONCLUSIONS

The onset of mood disorders is frequently preceded by identifiable depressive episodes and nonmood disorders. These precursors differed by mood subtype in offspring. High-risk offspring with these precursors should be closely monitored to prevent the further development of MDD or conversion to BPD.

Aberrant probabilistic reinforcement learning in first-degree relatives of individuals with bipolar disorder

BACKGROUND

Motivational dysregulation represents a core vulnerability factor for bipolar disorder. Whether this also comprises aberrant learning of stimulus-reinforcer contingencies is less clear.

METHODS

To answer this question, we compared healthy first-degree relatives of individuals with bipolar disorder (n = 42) known to convey an increased risk of developing a bipolar spectrum disorder and healthy individuals (n = 97). Further, we investigated the effects of the behavioral activation system (BAS) on reinforcement learning across the entire sample. All participants were assessed with a probabilistic learning task that distinguishes learning from positive and negative feedback. Main outcome measures included choice frequencies and learning rate parameters generated by computational reinforcement learning algorithms.

RESULTS

First-degree relatives choose more rewarding stimuli more consistently and showed marginally reduced learning rates from unexpected negative feedback. Further, first-degree relatives had lower BAS scores than controls, which were negatively associated with learning rates from unexpected negative feedback.

LIMITATIONS

However as probands also reported other mental disorders such as Attention-Deficit/Hyperactivity Disorder and substance abuse among their first-degree relatives, we cannot know, whether these findings are specific to the risk for bipolar disorder.

CONCLUSION

The behavior of first-degree relatives of individuals with bipolar disorder, who also display increased BAS sensitivity, is less influenced by unexpected negative feedback. This reduced learning from unexpected negative feedback biases subsequent choices towards stimuli with higher probabilities for a reward. In sum, our results confirm the role of aberrant reinforcement learning in the pathophysiology of bipolar disorder.

Uppsala Longitudinal Adolescent Depression Study (ULADS)

PURPOSE

To present the Uppsala Longitudinal Adolescent Depression Study, initiated in Uppsala, Sweden, in the early 1990s. The initial aim of this epidemiological investigation was to study the prevalence, characteristics and correlates of adolescent depression, and has subsequently expanded to include a broad range of social, economic and health-related long-term outcomes and cost-of-illness analyses.

PARTICIPANTS

The source population was first-year students (aged 16-17) in upper-secondary schools in Uppsala during 1991-1992, of which 2300 (93%) were screened for depression. Adolescents with positive screening and sex/age-matched peers were invited to a comprehensive assessment. A total of 631 adolescents (78% females) completed this assessment, and 409 subsequently completed a 15-year follow-up assessment. At both occasions, extensive information was collected on mental disorders, personality and psychosocial situation. Detailed social, economic and health-related data from 1993 onwards have recently been obtained from the Swedish national registries for 576 of the original participants and an age-matched reference population (N≥200 000).

FINDINGS TO DATE

The adolescent lifetime prevalence of a major depressive episode was estimated to be 11.4%. Recurrence in young adulthood was reported by the majority, with a particularly poor prognosis for those with a persistent depressive disorder or multiple somatic symptoms. Adolescent depression was also associated with an increased risk of other adversities in adulthood, including additional mental health conditions, low educational attainment and problems related to intimate relationships.

FUTURE PLANS

Longitudinal studies of adolescent depression are rare and must be responsibly managed and utilised. We therefore intend to follow the cohort continuously by means of registries. Currently, the participants are approaching mid-adulthood. At this stage, we are focusing on the overall long-term burden of adolescent depression. For this purpose, the research group has incorporated expertise in health economics. We would also welcome extended collaboration with researchers managing similar datasets.

Prevalence of current anxiety disorders in people with bipolar disorder during euthymia: a meta-analysis

BACKGROUND

Anxiety disorders are highly prevalent in people with bipolar disorder, but it is not clear how many have anxiety disorders even at times when they are free of major mood episodes. We aimed to establish what proportion of euthymic individuals with bipolar disorder meet diagnostic criteria for anxiety disorders.

METHOD

We performed a random-effects meta-analysis of prevalence rates of current DSM-III- and DSM-IV-defined anxiety disorders (panic disorder, agoraphobia, social anxiety disorder, generalized anxiety disorder, specific phobia, obsessive-compulsive disorder, post-traumatic stress disorder, and anxiety disorder not otherwise specified) in euthymic adults with bipolar disorder in studies published by 31 December 2015.

RESULTS

Across 10 samples with 2120 individuals with bipolar disorder, 34.7% met diagnostic criteria for one or more anxiety disorders during euthymia [95% confidence interval (CI) 23.9-45.5%]. Direct comparison of 189 euthymic individuals with bipolar disorder and 17 109 population controls across three studies showed a 4.6-fold increase (risk ratio 4.60, 95% CI 2.37-8.92, p < 0.001) in prevalence of anxiety disorders in those with bipolar disorder.

CONCLUSIONS

These findings suggest that anxiety disorders are common in people with bipolar disorder even when their mood is adequately controlled. Euthymic people with bipolar disorder should be routinely assessed for anxiety disorders and anxiety-focused treatment should be initiated if indicated.

A systematic review and meta-analysis of prospective transition from major depression to bipolar disorder

OBJECTIVE

Some people with major depressive disorder (MDD) may be at a pre-onset stage for bipolar disorder (BD), where early identification or prevention efforts may be feasible. We aimed to identify rates and characteristics predictive of transition to BD in prospective follow-up studies of people with MDD.

METHODS

Using a systematic search strategy, we identified studies with a diagnostic ascertainment of MDD and BD of an adequate standard, and where the minimum length of follow-up was 6 months. We examined the incidence and point prevalence of BD and the pooled odds ratios (OR) for baseline predictors.

RESULTS

From 5554 unique publications, 56 were included. Nearly a quarter of adults (22.5%) and adolescents with MDD followed up for a mean length of 12-18 years developed BD, with the greatest risk of transition being in the first 5 years. The meta-analysis identified that transition from MDD to BD was predicted by family history of BD (OR = 2.89, 95% CI: 2.01-4.14, N = 7), earlier age of onset of depression (g = -0.33, SE = 0.05, N = 6) and presence of psychotic symptoms (OR = 4.76, 95% CI: 1.79-12.66, N = 5).

CONCLUSIONS

Participants with the identified risk factors merit closer observation and may benefit from prevention efforts, especially if outcomes broader than BD are considered.

Parental separation in childhood as a risk factor for depression in adulthood: a community-based study of adolescents screened for depression and followed up after 15 years

BACKGROUND

Earlier research has investigated the association between parental separation and long-term health outcomes among offspring, but few studies have assessed the potentially moderating role of mental health status in adolescence. The aim of this study was to analyze whether parental separation in childhood predicts depression in adulthood and whether the pattern differs between individuals with and without earlier depression.

METHODS

A community-based sample of individuals with adolescent depression in 1991-93 and matched non-depressed peers were followed up using a structured diagnostic interview after 15 years. The participation rate was 65% (depressed n = 227; non-depressed controls n = 155). Information on parental separation and conditions in childhood and adolescence was collected at baseline. The outcome was depression between the ages 19-31 years; information on depression was collected at the follow-up diagnostic interview. The statistical method used was binary logistic regression.

RESULTS

Our analyses showed that depressed adolescents with separated parents had an excess risk of recurrence of depression in adulthood, compared with depressed adolescents with non-separated parents. In addition, among adolescents with depression, parental separation was associated with an increased risk of a switch to bipolar disorder in adulthood. Among the matched non-depressed peers, no associations between parental separation and adult depression or bipolar disorder were found.

CONCLUSIONS

Parental separation may have long-lasting health consequences for vulnerable individuals who suffer from mental illness already in adolescence.

Early interventions for youths at high risk for bipolar disorder: a developmental approach

In recent decades, ongoing research programmes on primary prevention and early identification of bipolar disorder (BD) have been developed. The aim of this article is to review the principal forms of evidence that support preventive interventions for BD in children and adolescents and the main challenges associated with these programmes. We performed a literature review of the main computerised databases (MEDLINE, PUBMED) and a manual search of the literature relevant to prospective and retrospective studies of prodromal symptoms, premorbid stages, risk factors, and early intervention programmes for BD. Genetic and environmental risk factors of BD were identified. Most of the algorithms used to measure the risk of developing BD and the early interventions programmes focused on the familial risk. The prodromal signs varied greatly and were age dependent. During adolescence, depressive episodes associated with genetic or environmental risk factors predicted the onset of hypomanic/manic episodes over subsequent years. In prepubertal children, the lack of specificity of clinical markers and difficulties in mood assessment were seen as impeding preventive interventions at these ages. Despite encouraging results, biomarkers have not thus far been sufficiently validated in youth samples to serve as screening tools for prevention. Additional longitudinal studies in youths at high risk of developing BD should include repeated measures of putative biomarkers. Staging models have been developed as an integrative approach to specify the individual level of risk based on clinical (e.g. prodromal symptoms and familial history of BD) and non-clinical (e.g. biomarkers and neuroimaging) data. However, there is still a lack of empirically validated studies that measure the benefits of using these models to design preventive intervention programmes.

[Adolescent manic-depressive disorders: Clinical aspects]

More than 50% of bipolar disorders diagnosed among adults first appeared before the age of 18. It is well established that adolescence is the high-risk period for the onset of major mood episodes associated with bipolar disorders. Even though there are few early-onset bipolar disorders, they are very severe. The most robust risk factor predicting bipolar disorder is a positive family history. Morbidity, mortality, and suicidality are high and have a severe impact on overall functioning, professional integration, family life, and affective relationships. Improving diagnosis of early symptoms should ameliorate these patients' prognosis.

Conversion from depression to bipolar disorder in a cohort of young people in England, 1999-2011: A national record linkage study

OBJECTIVE

To estimate the conversion rate from unipolar depression (ICD10 codes F32-F33) to bipolar disorder (BP) (ICD10 codes F31) in an English national cohort. It was hypothesised that early-onset BP (age <18 years) is a more severe form of the disorder, with a more rapid, and higher rate of conversion from depression to BP.

METHOD

This record linkage study used English national Hospital Episode Statistics (HES) covering all NHS inpatient and day case admissions between 1999 and 2011.

RESULTS

The overall rate of conversion from depression to BP for all ages was 5.65% (95% CI: 5.48-5.83) over a minimum 4-year follow-up period. The conversion rate from depression to BP increased in a linear manner with age from 10-14 years - 2.21% (95% C: 1.16-4.22) to 30-34 years - 7.06% (95% CI: 6.44-7.55) (F1,23=77.6, p=0.001, R(2)=0.77). The time to conversion was constant across the age range. The rate of conversion was higher in females (6.77%; 95% CI: 6.53-7.02) compared to males, (4.17%; 95% CI: 3.95-4.40) (χ(2)=194, p<0.0001), and in those with psychotic depression 8.12% (95% CI: 7.65-8.62) compared to non-psychotic depression 5.65% (95% CI: 5.48-5.83) (χ(2)=97.0, p<0.0001).

LIMITATIONS

The study was limited to hospital discharges and diagnoses were not standardised.

CONCLUSIONS

Increasing conversion rate from depression to bipolar disorder with age, and constant time for conversion across the age range does not support the notion that early-onset BP is a more severe form of the disorder.