To our knowledge, this is the largest study to date examining prevalence, demographic and clinical correlates of comorbid anxiety disorder among children and adolescents with BP.
Forty-four percent of BP youth in our sample met criteria for at least one lifetime anxiety disorder, most commonly SAD and GAD; 18% had two or more lifetime anxiety disorders. On average, the onset of anxiety predated the onset of BP. After adjusting for significant demographic factors and BP subtypes, youth with BP/anxiety, as compared with BP/no-anxiety, showed significantly higher rates of BP-II, longer duration of mood symptoms, higher current depression scores, lower likelihood of reporting an index episode of the manic subtype, higher rates of familial depression, and had a worst lifetime depressive episode characterized by greater severity of hopelessness, and aches and pains.
Our findings are consistent with those of previous studies in which anxiety disorders, particularly SAD and GAD, have been reported at high rates among youth and adults with BP 6, 8–10, 18, 39–45
. Also similar to other studies in the child and adult literature, we found that BP subjects with comorbid anxiety disorders were more likely to have a diagnosis of BP-II 19, 42, 44, 46–48
, longer duration of mood symptoms, and greater severity of depressive episodes 49–53
. This association may be related to the fact that BP-II has a more chronic course and outcome, longer length of illness, shorter cycles, and greater number of episodes, more major and minor depressive episodes, shorter well intervals between episodes, and lower rates of recovery 54, 55
Moreover, similar to the BP 9, 56
and unipolar depression 57, 58
literature we found that, on average, the anxiety disorders preceded the onset of the mood disorder. Contrary to our initial hypothesis 10, 40, 59–61
, age onset of BP episode did not differ between the two groups.
These findings are clinically relevant because currently the first line pharmacological treatments for anxiety disorders in youth are the selective serotonin reuptake inhibitors (SSRIs) 23, 24
. SSRIs have been shown to trigger or destabilize BP symptoms 25
. Thus, it is critically important to evaluate a child presenting with anxiety for the presence of manic or hypomanic symptoms, especially if depressive symptoms and a positive family history of mood disorders are also present. Although hypomanic symptoms can be difficult to ascertain in youth due to the unique developmental presentation 62
as well as symptom overlap with other conditions including depression and anxiety, recent studies clearly demonstrate that mania/hypomania in youth can be reliably diagnosed 3
. Additionally, anxious children treated with antidepressants should be carefully monitored for the presence of manic/hypomanic symptoms 40
Little is known about the most efficacious treatments for the treatment of comorbid anxiety in youth with BP. Future studies may evaluate the efficacy of psychotherapy approaches with empirical support for the treatment of anxious youth, such as cognitive-behavioral therapy 22
. The risk/benefit ratio of the use of SSRIs in youth with BP who are on concurrent mood stabilizers also may be explored.
Interestingly, we found that youth with BP/anxiety showed significantly more family history of depression. This finding is consistent with Wozniak et al. (2002) 63
, who reported elevated risk for both BP and anxiety among relatives of BP/anxiety probands. As such, this group suggested that comorbid anxiety and BP may represent a genetic subtype of BP. Furthermore, a recent study by Birmaher and colleagues (2009) 11
found that offspring of parents with BP had higher rates of anxiety disorders than offspring of control parents suggesting that anxiety may be a precursor of BP among BP offspring. Thus, systematic evaluation of youth with anxiety disorder and family history of mood disorders is warranted because these youth may be at high risk to develop BP.
Contrary to our initial hypothesis 4, 21, 49, 59, 64–67
, we did not find significantly more suicidal behaviors 9
, or substance use disorders in the BP with comorbid anxiety group as compared to those without. These discrepancies may be explained by the fact that most subjects in this study have not yet reached the age of highest risk for these conditions. Nonetheless, youth with BP and anxiety had significantly more suicidal ideation, as well as hopelessness during the most severe lifetime depressive episode than subjects without comorbid anxiety. Since hopelessness is highly associated with suicide attempts and suicide 68–70
, careful evaluation and monitoring of suicide risk in youth with BP/anxiety is clearly indicated. Also contrary to our initial hypothesis 4, 21
, we did not find poorer functioning in the BP group with comorbid anxiety as compared with those without. It is possible that the impact of BP on global functioning during childhood and adolescence is significantly profound such that any additional impairment associated with comorbid anxiety is relatively negligible.
Finally, after adjusting for multiple comparisons, youth with BP and comorbid anxiety reported more aches and pains than those without anxiety, as is the case in adults studies 71
. It has been well-documented that anxious youth experience somatic complaints and tend to consult primary care physicians or pediatricians before mental health clinicians 72
. Thus, it is important to educate such front-line providers about the possibility that anxious youth with a positive family history of mood disorder may also have BP.
It is important to note the limitations of this study. First, as most subjects were Caucasian and were recruited primarily from outpatient clinical settings, the generalizability of the findings remains uncertain. However, a community-based study of non-referred adolescents with BP reported similarly high rates of comorbid anxiety disorders 73
. Second, subjects were ascertained for bipolarity. Thus, results may not apply to subjects whose primary diagnosis is anxiety and then develop BP. Third, this study is cross-sectional and data was ascertained retrospectively. We are currently following these subjects longitudinally, and we will thus be able to further examine the associations over follow-up. Finally, no psychiatric control group was included. Thus, using the current sample, we cannot conclude that lifetime anxiety disorders are more common in youth with BP than in youth with other childhood psychiatric disorders (e.g., major depressive disorder).
In summary, anxiety disorders usually predate the onset of BP and are very common in youth with BP, especially those with BP-II, longer duration of mood symptoms, more severe depressions, and family history of depression. Given the clinical and treatment implications of these findings, early identification and accurate diagnosis for these youth is very important. Randomized trials to evaluate treatments for anxiety in youth with BP are needed. Finally, longitudinal studies to determine the impact of comorbid anxiety disorder on the course and outcome of pediatric BP spectrum disorders are warranted.