Finding a model for comorbidity between attention deficit hyperactivity disorder and epilepsy

Close relationships between attention deficit hyperactivity disorder (ADHD) and epilepsy has been suggested due to prevalence of ADHD symptoms among patients with epilepsy than in the general population. Like epilepsy-depression connection, bi-directional relationships are suggested to underlie the predisposition of patients with ADHD to epilepsy and vice versa. Spontaneously hypertensive rats (SHRs) are characterized with typical behavioral symptoms such as hyperactivity, an attention deficit and impulsiveness, deficient sustained attention and decreased monoamine functioning. Our experimental findings suggest that SHRs might be used as a relevant model of comorbidity between ADHD and epilepsy. Spontaneously hypertensive rats demonstrate abnormal electrophysiological and behavioral characteristics as well as monoamine deficit in the frontal cortex and the hippocampus, which are also evident in epileptic rats. In addition, SHRs shows higher seizure susceptibility in models of temporal lobe epilepsy and disturbed circadian rhythms. Taken together, experimental findings suggest that SHRs could be used to explore the mechanism underlying bi-directional link of ADHD and epilepsy and as a screening method for mechanism-driven therapeutic approaches.