Attention-deficit hyperactivity disorder may be associated with decreased central brain-derived neurotrophic factor activity: Clinical, and therapeutic implications

Attention-deficit hyperactivity disorder (ADHD) is a common childhood psychiatric disorder. Despite intensive research efforts, the aetiology of ADHD remains unknown. Current evidence suggests that the aetiology of ADHD is heterogeneous, comprising of multiple factors. Recently, it has been proposed that brain-derived neurotrophic factor (BDNF), a member of the neurotrophic factor family, may be implicated in the pathogenesis of ADHD. This hypothesis is supported by recent genetic studies in ADHD. Drawing on findings from studies into the drugs for ADHD relating to central BDNF expression, hyperactivity in BDNF knockout mice, BDNF effects in midbrain dopaminergic function and the close association between BDNF and the dopamine transporter (an important molecule for ADHD pathogenesis), it is proposed here that decreased central BDNF, particularly in the midbrain region, may play an important role in the pathogenesis ADHD. This hypothesis may have some implications for clinical findings in ADHD (for example, the co-morbidity between ADHD and major depression), and provide a new direction for the development of medication for ADHD treatment. (c) 2006 Elsevier Ltd. All rights reserved.