Co-morbid conditions had been known to characterize adolescent onset bipolar disorders 123 and co-morbid disorders impact negatively on outcome in adolescents with bipolar disorder 1245. Youths with bipolar disorder had been found to be prone to sexual abuse 6 and often exhibit sexual risk behavior 7. Family and social dynamics had also been shown to influence co-morbidity and outcome in adolescent onset bipolar disorder 5.

There are dearth of information on prevalence and pattern of co-morbid disorders in adolescent onset bipolar disorder in Nigeria and other sub-Saharan African countries. Information is also limited on sexual risk behavior and its associated factors in adolescent onset bipolar disorder in this environment.

Attempt was made by this study to determine the prevalence and pattern of co-morbid diagnoses in Nigerian adolescents with bipolar disorder. It also determined the prevalence of sexual risk behavior and its associated factors in these adolescents. It assessed the association between co-morbid disorders and history of sexual risk behavior among the adolescents.

A total of forty six (46) adolescents were followed up. There were 29 (63.0%) males and 17 (37.0%) females. The age range of the adolescents was between 15 and 18 years, the mean age was 16.90 ± 1.07. The mean age at onset of bipolar disorder symptoms in the adolescents was 15.02 ± 1.02. The mean number of hospital admissions in the past year during follow up period among the adolescents was 2.85 ± 1.07. Twelve (26.1%), 16 (34.8%) and 18 (39.1%) of the adolescents were classified as having 'high', 'moderate' and 'low' level of religion activities respectively. Twenty eight (60.9%) and 18 (39.1%) of the parents of the adolescents were married and single parents respectively. Table 1 showed the socio-demographic variables and clinical parameters of the adolescents.

About forty eight percent of the adolescents had co-morbid psychiatric and medical disorders in addition to the bipolar disorder. The pattern of co-morbid disorders included cannabis use disorders, alcohol use disorders, conduct disorder with or without other psychoactive substances use, and HIV infection, which was a chance finding heralded by presentation of symptoms that arose clinical suspicion of the diagnosis in one of the adolescents. Therefore, substance use disorders accounted for the significant ratio of co-morbidity in these adolescents with bipolar disorder. Substance use disorders had also been noted to be a prominent problem in healthy adolescents in the general population in Nigeria. However, the findings among these adolescents with bipolar disorder revealed some salient differences compared to what obtained in the past general population studies 910. For example, the prevalence of alcohol use disorders of 8.7% found in this study is significantly lower than that of 15.6% found in one study that assessed people of comparative age groups in high school in Nigeria 9 and that of about 14% for past year in another study that cut across different age groups of Nigerian population 10. Another interesting finding is that while alcohol use problems tend to be more common among the males in these general population studies 910, the contrast was the finding in these adolescents with bipolar disorder. The prevalence of 23.9% Cannabis use disorder found among these adolescents significantly exceeded the figure of 3.7% documented among people of comparable age range and 0.4% documented in people of different age range in Nigeria general population respectively 910. The high prevalence of Cannabis use disorder in adolescents with bipolar disorder in this environment need to be further explored to determine factor(s) that may be responsible for this finding.

History of sexual risk behavior was present in about forty six percent of the adolescents. Having a history of sexual risk behavior was significantly associated with presence of co-morbid psychiatric and medical diagnoses. Having a history of sexual risk behavior was also significantly associated with level of religion activities and marital status of the parents, with 'moderate' to 'high' level of religion activities and married status of the parents offering protective effect on exhibiting sexual risk behaviors. The prevalence of 45.7% history of sexual risk behavior found in adolescents with bipolar disorder in this study is significantly higher than the observation of prevalence rates of 25.0 to 29.3% documented among healthy adolescents of comparative age drawn from the general population in one study 11. This suggests that the presence of diagnosis of bipolar disorder in adolescents in this environment may make them more prone to exhibiting sexual risk behavior and its attendant consequences.

Co-morbidity had been documented to characterized early onset bipolar disorder 135. The prevalence of co-morbid disorders of forty eight percent found in this study is comparable to the rates of co-morbid disorders, especially of substance use disorders found in earlier studies carried out in developed countries of the world 312.

Manic symptoms and co-morbid substance use disorders in adolescent bipolar disorder predispose affected adolescent to impulsivity, impaired judgment and risk taking behavior. These attributes could make such adolescent prone to sexual risk behavior. About forty six percent of adolescents that participated in this study had history of sexual risk behavior and our finding is in line with that of Meade et al 7 who found closely related prevalence of sexual risk behavior in patients with bipolar disorder. Co-morbid psychoactive substance use disorders accounted for the highest prevalence of co-morbidity among adolescents with bipolar disorder studied and a significant association was found between presence co-morbidity and history of sexual risk behavior. This finding concurred with that of Meade et al 7 that found association between history of sexual risk behavior and co-morbid psychoactive substance use disorders in patients with bipolar disorder.

Sexual risk behavior in these adolescents predisposes them to risk of sexually transmitted diseases (STDs). Presence of HIV infection as a co-morbid condition was a chance finding in one of these adolescents with bipolar disorder, this was because they were not routinely screened for any STDs including HIV infection unless there are symptoms presentation that arose suspicion of the diagnosis as occurred in one of these adolescents. Co-morbidity of HIV infection and other STDs in adolescent with bipolar disorder may need further evaluation in future studies. Although, the prevalence of about two percent presence of HIV co-morbidity among these adolescents is significantly lower than the rate of five percent documented as community prevalence of HIV infection in Nigeria by the 2003 Sentinel Survey 13, it still remained a pointer to the need to pay attention to issue of STDs in adolescents with bipolar disorder. Presence of mania symptoms had been noted to predispose individuals with bipolar disorder to engage in sexual risk behaviors and thus in turn predispose them to contracting HIV infection and it had also been documented that primary HIV infection in an individual may present with classical symptoms suggestive of mania. Therefore, a vicious cycle effect between mania symptoms and HIV infection had been suggested 1415.

The association of history of sexual risk behavior with marital status of the parents, with adolescents of single parents being more likely to have such history underscored the importance of family and social dynamics in adolescent onset bipolar disorder outcome 5. The family and social dynamics of adolescents with bipolar disorder should be given a good attention when planning interventions for such adolescents.

Presence of co-morbid disorders, especially psychoactive substance use disorders and sexual risk behavior and its attendant complications in adolescent onset bipolar disorder is a pointer to poor outcome and could cause the affected adolescents significant impairment in functioning 1617 and mortality from risk taking behaviors and suicidal acts 1819.

Adolescents with bipolar disorder who suffer co-morbid disorders, especially psychoactive substance use disorders and who exhibit impulsivity and sexual risk behavior may need to be given special attention when planning interventions for children and adolescents with bipolar disorder. This may help to improve long term outcome in this group of adolescents. To the best of our knowledge, there are no past studies that have examined issue of co-morbidity in adolescent onset bipolar disorder in this environment and therefore the present data would provide a template for future longitudinal studies among adolescents with bipolar disorder in this environment.

The authors declare that they have no competing interests.

All authors contributed to the conception of the study. MOB wrote the initial draft of the manuscript and all authors were involved in revising the manuscript. All authors read and approved the final draft of the manuscript.