Attention-deficit hyperactivity disorder in bipolar disorder

Abstract

Attention-deficit hyperactivity disorder (ADHD) is a developmental disorder, i.e., it is by definition present from childhood. The main features characterizing ADHD are the difficulties to regulate attention, activity level, and impulses. The hallmark of bipolar disorder is episodic mood alterations with restitution between episodes. Although debut in childhood may occur, bipolar disorder typically debuts in late adolescence or early adulthood. The overarching aim with this thesis was to study the importance of ADHD symptoms in adult bipolar disorder.

The first study assessed the prevalence of childhood and current ADHD in a cohort of adult bipolar patients. Childhood ADHD was a significant predictor for more frequent hypomanic, depressive, and mixed episodes, as well as more violent incidents, regardless of whether ADHD criteria were fulfilled in adulthood or not. It is suggested that bipolar disorder with a history of childhood ADHD might represent a developmental subtype of bipolar disorder.

The second study examined adult personality traits and affective regulation in euthymic bipolar patients with and without a history of childhood ADHD, as well as in a group of pure ADHD patients. Those with childhood ADHD had more affective dysregulation than bipolar patients without childhood ADHD. Childhood ADHD was a significant predictor for the development of affective dysregulation in terms of anxiety, stress-susceptibility, irritability, aggression, and impulsivity in bipolar patients. Whereas the personality profile in bipolar patients with childhood ADHD differed from pure bipolar patients, it closely resembled patients with pure ADHD.

The third study compared the levels of cerebrospinal fluid monoamine metabolites in euthymic patients with bipolar disorder type 1, with and without a history of childhood ADHD. The results demonstrated significantly lower levels of dopamine (HVA) and serotonin metabolites (5-HIAA) in those with a history of childhood ADHD, compared to those without ADHD. This lends biological support for the notion that bipolar disorder type 1 with childhood ADHD represents a specific subtype of bipolar disorder.

The fourth population-based study examined the risk for bipolar disorder and schizophrenia in ADHD probands and their relatives in comparison with matched controls. The aim was to test the hypothesis that ADHD is familially associated to bipolar disorder, but not to schizophrenia. The results showed that persons with ADHD were at considerably increased risk for bipolar disorder, and more importantly, so were their parents and siblings. Contrary to the hypothesis, however, persons with ADHD, along with their parents and siblings, had an equally increased risk for schizophrenia. Our results suggest that ADHD is familially associated with both bipolar disorder and schizophrenia.