Characterizing the clinical profile of mania without major depressive episodes: a systematic review and meta-analysis of factors associated with unipolar mania

BACKGROUND

The diagnostic concept of unipolar mania (UM), i.e. the lifetime occurrence of mania without major depressive episodes, remains a topic of debate despite the evidence accumulated in the last few years. We carried out a systematic review and meta-analysis of observational studies testing factors associated with UM as compared to bipolar disorder with a manic-depressive course (md-BD).

METHODS

Studies indexed up to July 2022 in main electronic databases were searched. Random-effects meta-analyses of the association between UM and relevant correlates yielded odds ratio (OR) or standardized mean difference (SMD), with 95% confidence intervals (CIs).

RESULTS

Based on data from 21 studies, factors positively or negatively associated with UM, as compared to md-BD, were: male gender (OR 1.47; 95% CI 1.11-1.94); age at onset (SMD -0.25; 95% CI -0.46 to -0.04); number of hospitalizations (SMD 0.53; 95% CI 0.21-0.84); family history of depression (OR 0.55; 95% CI 0.36-0.85); suicide attempts (OR 0.25; 95% CI 0.19-0.34); comorbid anxiety disorders (OR 0.35; 95% CI 0.26-0.49); psychotic features (OR 2.16; 95% CI 1.55-3.00); hyperthymic temperament (OR 1.99; 95% CI 1.17-3.40). The quality of evidence for the association with previous suicide attempts was high, moderate for anxiety disorders and psychotic features, and low or very low for other correlates.

CONCLUSIONS

Despite the heterogeneous quality of evidence, this work supports the hypothesis that UM might represent a distinctive diagnostic construct, with peculiar clinical correlates. Additional research is needed to better differentiate UM in the context of affective disorders, favouring personalized care approaches.

Characterization of clinical features and comorbidities between bipolar affective disorder with and without depressive episodes

BACKGROUNDS

A proportion of patients with bipolar disorder (BD) manifests with only unipolar mania (UM). This study examined relevant clinical features and psychosocial characteristics in UM compared with depressive-manic (D-M) subgroups. Moreover, comorbidity patterns of physical conditions and psychiatric disorders were evaluated between the UM and D-M groups.

METHODS

This clinical retrospective study (N = 1015) analyzed cases with an average of 10 years of illness duration and a nationwide population-based cohort (N = 8343) followed up for 10 years in the Taiwanese population. UM was defined as patients who did not experience depressive episodes and were not prescribed adequate antidepressant treatment during the disease course of BD. Logistic regression models adjusted for relevant covariates were used to evaluate the characteristics and lifetime comorbidities in the two groups.

RESULTS

The proportion of UM ranged from 12.91% to 14.87% in the two datasets. Compared with the D-M group, the UM group had more psychotic symptoms, fewer suicidal behaviors, a higher proportion of morningness chronotype, better sleep quality, higher extraversion, lower neuroticism, and less harm avoidance personality traits. Substantially different lifetime comorbidity patterns were observed between the two groups.

CONCLUSIONS

Patients with UM exhibited distinct clinical and psychosocial features compared with patients with the D-M subtype. In particular, a higher risk of comorbid cardiovascular diseases and anxiety disorders is apparent in patients with D-M. Further studies are warranted to investigate the underlying mechanisms for diverse presentations in subgroups of BDs.

The nosological status of unipolar mania and hypomania within UK Biobank according to objective and subjective measures of diurnal rest and activity

BACKGROUND

There is uncertainty whether unipolar mania is a discrete sub-type of bipolar disorder. Disrupted rest/activity rhythms are a key feature of bipolar disorder (BD) but have not been well characterised in unipolar mania/hypomania (UM). We compared subjective and objective rest/activity patterns, demographic and mental health outcomes across BD, UM and control groups.

METHODS

UK residents aged 37-73 years were recruited into UK Biobank from 2006 to 2010. BD, UM and control groups were identified via a mental health questionnaire. Demographic, mental health and subjective sleep outcomes were self-reported. Accelerometery data were available for a subset of participants, and objective measures of sleep and activity were derived.

RESULTS

A greater proportion of males met UM criteria, and more females were in the BD group. Both BD and UM groups had poor mental health outcomes vs. controls. Objectively measured activity differed between all three groups: UM had highest levels of activity and BD lowest. The UM group had shorter sleep duration compared to controls. Subjective rest/activity measures showed that both mood disorder groups (compared to controls) had later chronotype preference, more disturbed sleep and increased difficulty getting up in the morning. However, the UM group were more likely to report an early chronotype compared to BD and control groups.

CONCLUSIONS

BD and UM share features in common, but key differences support the proposition that UM may be a distinct and more clinically homogenous disorder. UM was characterised by a higher proportion of males, early chronotype, increased activity and shorter sleep duration.

Is unipolar mania a distinct entity: findings from the bipolar disorder course and outcome study from India (BiD-CoIN study)

AIM

This study aimed to evaluate the prevalence of unipolar mania (UM) in a group of patients of bipolar disorder (BD). Additionally, effort was made to evaluate the demographic, clinical and treatment related factors, which distinguish subjects of UM from BD.

METHODOLOGY

Seven hundred and seventy-three patients with BD, of at least 10 years duration, recruited from 14 General Hospital Units of tertiary care centers from India were evaluated for UM.

RESULTS

The prevalence of UM, varied from 5.4% to 20.3%, depending on the definition used. With the most stringent definition of ≥4 episodes of mania and at least 5 years of follow-up, the prevalence of UM was 5.4%. Compared to patients of BD, who have episodes other than mania too, those with UM had lower proportion of patients with lifetime history of suicide attempts, spent less time in the episodes in their lifetime and had lower severity of residual depressive and manic symptoms. Further, compared to those with episodes other than mania too, those with UM had higher number of manic episodes per year of illness, had higher proportion of patients who had more than five episodes in the lifetime and had higher proportion of those with at least one episode with psychotic symptoms in the lifetime.

CONCLUSION

The present study suggests that a small proportion of patients with BD have UM course and this runs a different clinical course compared to that seen in patients with traditionally recognized as BD.

Epidemiology and course of unipolar mania: results from the national epidemiologic survey on alcohol and related conditions (NESARC)

BACKGROUND

Unipolar mania (UM), in which only manic episodes occur during the course of illness, may be an important clinical manifestation of bipolar disorder that is under-recognized and understudied. The aim of this study is, for the first time, to examine the prevalence of UM and its clinical characteristics in the community.

METHODS

Among a total of 1,411 subjects with bipolar I disorder, we evaluated the prevalence of UM using three different criteria proposed in previous studies. We compared the clinical characteristics of subjects with UM to those with a more classic bipolar presentation with mania and lifetime major depressive episode (MDE). We additionally explored the proportion of subjects with UM who later experience at least one MDE during a 3-year follow-up period and determined risk factors for converting from UM to classic bipolar disorder.

RESULTS

The prevalence rate of UM among those with bipolar disorder ranged from 5.0 to 7.2% depending on the criteria. UM was more common in male and nonwhite subjects. About half of individuals with UM experienced subthreshold depression. Individuals with UM had lower rates of comorbid anxiety disorders or attention deficit hyperactivity disorder (ADHD). During the follow-up, about 18% of subjects with UM experienced MDEs. Male, nonwhite, comorbid generalized anxiety disorder and ADHD predicted an increased transition from UM to classic bipolar disorder. Subthreshold depression was not associated with the risk of the transition.

CONCLUSIONS

UM is an infrequent but clinically distinct subtype of bipolar I disorder. Further research delineating the characteristics of UM is warranted.