In the past 2 decades, there has been increasing awareness that bipolar disorders begin in juvenile years (1–5), and since 1980 diagnostic criteria for bipolar disorder in adults have also been used to diagnose mania in children. Obstacles to identifying and diagnosing mania in children and adolescents essentially include the diversity in clinical presentation within and across episodes and the symptomatic overlap with externalizing disorders commonly found in childhood, such as attention-deficit hyperactivity disorder (ADHD) and conduct disorder (CD) (4, 6–8). There is consensus that uncomplicated classic manic-depressive illness is rare in children and that in the case of comorbidity with externalizing disorders, the question is whether these latter and bipolar disorder actually represent distinct illnesses (9,10).

Epidemiological data on bipolar disorder in juvenile subjects are scarce and conflicting. A community study of adolescents in the US reported a 0.99% prevalence rate of full-blown bipolar disorder (11); periods of abnormally persistent, elevated, expansive, or irritable mood were prevalent (5.7%), although they did not fulfill criteria for bipolar I, bipolar II, or cyclothymia (11).

Manuscript received and accepted September 2001.
¹Researcher, Division of Child Neurology and Psychiatry, University of Pisa, IRCCS Stella Maris, Calambrone, Pisa, Italy. ²Researcher, Department of Psychiatry, University of Pisa, and Institute of Behavioural Sciences, Carrara-Pisa, Italy. ³Researcher, Department of Psychiatry, University of Pisa, and Institute of Behavioural Sciences, Carrara-Pisa, Italy. ⁴Researcher, Division of Child Neurology and Psychiatry, University of Pisa, IRCCS Stella Maris, Calambrone, Pisa, Italy. ⁵Researcher, Division of Child Neurology and Psychiatry, University of Pisa, IRCCS Stella Maris, Calambrone, Pisa, Italy. ⁶Professor of Psychiatry and Director, International Mood Center, Department of Psychiatry at the University of California at San Diego and Veterans Administration Medical Center, La Jolla , California. Address for correspondence: Dr Gabriele Masi, INPE–University of Pisa, Via dei Giacinti 2, 56018, Calambrone (Pisa) Italy
e-mail: masi@inpe.unipi.it

In another survey of adolescents, the prevalence of bipolar disorder varied from 0.6% to 13.3%, depending upon whether the duration and severity criteria were applied (12). There are no community studies of bipolar disorder in preteens.

Several predictors of bipolar disorder outcome in adolescents with major depression have been suggested: family history of bipolar disorder, sudden onset, presence of delusions, psychomotor retardation and hypersomnia, and pharmacologically induced (hypo)mania (13–15). Moreover, what seems unique to juvenile bipolar disorder is the almost invariable presence of other concomitant disorders. As in adults, comorbidity is the rule rather than the exception among children and adolescents with bipolar disorder. In particular, comorbidity with externalizing disorders has been widely reported, even if definitive conclusions have not been attained (4, 8–10). Other comorbidities, however, have also been observed, including anxiety disorders (11,7), drug and alcohol abuse (11,16), and eating and impulse-control disorders (11,17).

Although comorbidity with anxiety disorders appears as a clinically relevant phenomenon, it has not been studied as well as has comobidity with externalizing disorders. Akiskal and others reported that of the 44 offspring (aged 6 to 18 years old) of probands with bipolar disorder, 18.2% had initially received anxiety disorder diagnoses in an era when the latter were not even part of the official diagnostic practice (1). Bashir and others noted that concomitant anxiety disorders were present in 53% of adolescents with diagnosed mania or hypomania (18). In a representative community sample of 1709 adolescents (aged 14 to 18 years), 37 of 115 subjects (32.2%) meeting DSM-IV criteria for bipolar disorder or with subthreshold bipolar symptomatology were also found to meet criteria for specific anxiety disorders (11).