Attention-deficit/hyperactive disorder updates.

Area of Science:

• Neurodevelopmental disorders
• Genetics and epigenetics
• Neurobiology

Background:

• Attention-deficit/hyperactive disorder (ADHD) is a prevalent neurodevelopmental disorder impacting children's academic, social, and overall well-being.
• Despite existing knowledge, the precise pathogenesis of ADHD remains unclear, posing challenges for early diagnosis and effective management.
• The disorder incurs significant individual and societal costs.

Purpose of the Study:

• To review the pathogenic pathways of ADHD in children.
• To update current understanding of ADHD etiologies, including genetic and environmental factors, and their interactions.
• To examine findings from human studies and animal models, as well as epigenetic modifications.

Main Methods:

• A systematic literature search was conducted in PubMed using relevant keywords.
• The search encompassed all available years up to January 2022.
• The review focused on genetic associations, animal models, environmental influences, and epigenetic changes related to ADHD.

Main Results:

• Numerous genes (e.g., DRD1, DRD4, DAT1, MAOA, BDNF) have been associated with ADHD, with varying evidence from human and animal studies.
• Most animal models are knockouts and do not fully replicate human genetic alterations; ethnic variations in gene polymorphisms exist.
• The dopaminergic pathway is central to ADHD pathogenesis, influenced by environmental factors and epigenetic modifications like methylation and acetylation.

Conclusions:

• The dopaminergic pathway is critical in ADHD pathogenesis, but its interaction with environmental factors and other neurotransmitter pathways requires further investigation.
• Existing animal models have limitations in replicating human ADHD genetics, necessitating the development of more relevant models.
• Additional research into epigenetic modifications and the interplay between genetics and environment is crucial for advancing ADHD understanding and treatment.