Abstract
OBJECTIVES: Bipolar and ADHD are two diseases that exhibit similar traits but at different levels of severity. Understanding this behavior can help treatment of these disorders. METHOD: We hypothesize that there is a common partial genetic cause for both attention-deficit/hyperactivity disorder (ADHD) and bipolar disorders (BD), which is the reversal function of the dopamine neurotransporter DAT gate (see Figure 1) into an efflux mode. We analyze the dopamine chemistry in the neuron synapse under this assumption. RESULTS: The difference between ADHD and BD phenotypes is due either to the dopamine receptor (D2R) operation or to the threshold levels of the dopamine homeostatic control and the intensity of its operation. SIGNIFICANCE: The common cause of the two disorders could explain the frequent phenomenon of ADHD symptoms preceding BD beginning and the high comorbidity between these disorders.