Recently, children diagnosed with“pediatric bipolar disorder”are increasing specifically in United States. This clinical practice in United States does not fit the clinical impression by majority of Japanese psychiatrists that onset of bipolar disorder in children does exist but rare. These cases have severe mood dysregulation including irritability and aggression but do not satisfy the diagnostic criteria of bipolar I or II disorder. It is not known whether these cases will develop adult bipolar disorder. To avoid such over-diagnosis, a new category, Temper Dysregulation Disorder with Dysphoria(TDDD), was introduced in DSM-5 draft. Using this criteria, further studies should be performed to clarify the long term outcome and possible role of psychostimulant treatment.

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There has been a serious delay in recognizing early onset bipolar disorder (particularly childhood-onset) among psychiatrists in Japan, probably due to a possible problem of medical education and a lack of child psychiatrists. Although the same diagnostic criteria and subtypes of bipolar disorder are used for all ages of patients, clinical manifestation differs greatly between childhood and adult onset bipolar disorder. What makes the diagnosis of the disorder difficult in childhood may be such factors as behavioral rather than mood changes as main clinical manifestation, irregular and often rapid cycling of mood, a need for the assessment of how comorbid disorder(s), such as pervasive developmental disorder and AD/HD, influences clinical pictures, and a need to rule out medical conditions that cause mood symptoms (e.g. epilepsy, use of steroids). Finally, it is argued that, in order to improve the current situation regarding early onset bipolar disorder in Japan, the education of child psychiatry seems essential.

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The diagnosis of major depressive disorder(MDD)cannot be made in patients with major depressive episodes if they have shown hypomanic symptoms. However, hypomanic symptoms are often overlooked in daily clinical settings. Bipolar disorder(BD), especially bipolar II disorder(BDII), is liable to be misdiagnosed as MDD. Antidepressants may induce harmful events, such as manic switch, in patients with BD. Therefore, clinicians must carefully probe hypomanic episodes in patients with major depressive episodes. Moreover, the diagnosis of MDD should not be made lightly even if hypomanic episodes are not recognized, as patients with major depressive episodes may show hypomanic episodes during their clinical course. Early onset of major depressive episodes is regarded as one of the clinical signs in patients with BD rather than MDD. Many adolescents seek help with depressive symptoms in daily clinical settings. Clinicians should pay attention to unrecognized hypomanic symptoms. Patients may show one to four hypomanic symptoms during major depressive episodes. Such patients are regarded as having depressive mixed state, and that they should be diagnosed as having BDII rather than MDD.

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Periodic psychosis of puberty is a pathology often found in girls around the onset of menses, and it is characterized by psychological symptoms, such as periodic mood swings, behavioral inhibition, psychotic experiences and a dreamy state. Some studies consider it a mood disorder in preadolescence and classify it as atypical psychosis. However, others argue that it is a symptomatic psychosis of physiologically premature women. It is important to construct biological measures including concepts of trait marker and state marker when evaluating periodic psychosis. Moreover, some electroencephalograms to follow up possible disturbance of consciousness are essential. In this article, I would like to discuss an overview of clinical features, pathological basis, and treatment of periodic psychosis of puberty. I would also like to emphasize the importance of biologoical measures to better understand and evaluate psychosis, especially periodic psychosis.

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Childhood-onset schizophrenia has been clinically treated and studied presuming that it is on a continuum with adult-onset schizophrenia, and the two forms are almost the same pathological condition. On the other hand, concerning mood disorders in childhood, the presence of depression has been recognized from a relatively early period, but no consensus has yet been reached on bipolar disorder, even its concept. Therefore, we reviewed the literature regarding childhood-onset schizophrenia and mood disorders, particularly bipolar disorder, and also evaluated cautionary items in the differential diagnosis and the characteristics of the development course. Although adaptation/function before disease onset, experience of loss of parents, and brain imaging studies characteristic of each disorder were observed, there have been few studies that directly compared the two disorders. Concerning the developmental course such as the growth history, it may be necessary not only to evaluate clinical symptoms crosssectionally, but also to use a longitudinal approach, as has been observed in recent studies on schizophrenia. In the future, the clinical characteristics of bipolar disorder, particularly in Japan, should be evaluated with the addition of detailed descriptions of cases to clarify the developmental process of bipolar disorder and the course until its onset.

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Recent meta-analytic reviews on cognitive dysfunction in adult patients with bipolar disorder highlight traits-like deficits in attention/processing speed, episodic memory, and executive functions. These cognitive deficits have great impacts on social functioning of patients with BD even during euthymic state. Dysfunctional neural circuitries including prefrontal-striatal systems and medial temporal/diencephalic systems might be underlying behind the impairments. Growing evidences suggests that pediatric BD patients also experience traits-like cognitive impairments similar to those found in adult BD patients. Since cognitive studies on pediatric BD have confounds such as lack of consensus for diagnosis, high ADHD co morbidity, and possible impacts of medications on cognition, the results need to be interpreted with caution; however, the present findings support a view that pediatric BD and adult BD are continuous clinical entities presenting genetic and neuro-developmental abnormalities.

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