Cluster BB size.

Attention Deficit Hyperactivity Disorder (ADHD) is an increasingly prevalent neuropsychiatric disorder characterized by hyperactivity, inattention, and impulsivity. Symptoms emerge from underlying deficiencies in neurocircuitry, and recent research has suggested a role played by the gut microbiome. The gut microbiome is an ecosystem of interdependent taxa involved in an exponentially complex web of interactions, plus host gene and reaction pathways, some of which involve neurotransmitters with roles in ADHD neurocircuitry. Studies have analyzed the ADHD gut microbiome using macroscale metrics such as diversity and differential abundance, and have proposed several taxa as elevated or reduced in ADHD compared to Control. Few studies have delved into the complex underlying dynamics ultimately responsible for the emergence of such metrics, leaving a largely incomplete, sometimes contradictory, and ultimately inconclusive picture. We aim to help complete this picture by venturing beyond taxa abundances and into taxa relationships (i.e. cooperation and competition), using a publicly available gut microbiome dataset (targeted 16S, v3-4 region, qPCR) from an observational, case-control study of 30 Control (15 female, 15 male) and 28 ADHD (15 female, 13 male) undergraduate students. We first perform the same macroscale analyses prevalent in ADHD gut microbiome literature (diversity, differential abundance, and composition) to observe the degree of correspondence, or any new trends. We then estimate two-way ecological relationships by producing Control and ADHD Microbial Co-occurrence Networks (MCNs), using SparCC correlations (p ≤ 0.01). We perform community detection to find clusters of taxa estimated to mutually cooperate along with their centroids, and centrality calculations to estimate taxa most vital to overall gut ecology. We finally summarize our results, providing conjectures on how they can guide future experiments, some methods for improving our experiments, and general implications for the field.

注意缺陷与多动障碍（Attention Deficit Hyperactivity Disorder, ADHD）是一种日益高发的神经精神疾病，以多动、注意力不集中及冲动行为为核心特征。其症状源于神经环路的潜在功能缺陷，近年研究提示肠道菌群（gut microbiome）在该病的发生发展中可能发挥重要作用。肠道菌群是一个由相互依存的微生物类群组成的生态系统，参与一个呈指数级复杂度的相互作用网络，同时关联宿主基因与生理反应通路，其中部分通路涉及与ADHD相关神经环路功能相关的神经递质。

现有研究多采用多样性、差异丰度等宏观指标对ADHD患者的肠道菌群进行分析，并已提出若干在ADHD患者中相较于健康对照（Control）存在丰度升高或降低的微生物类群。但鲜有研究深入探究最终导致这些宏观指标出现的复杂底层动态机制，这使得当前的研究图景尚未完全明晰，且时常存在矛盾，最终难以得出定论。

本研究旨在突破现有仅关注微生物类群丰度的研究框架，转而聚焦类群间的相互作用（即协作与竞争关系），以期完善这一研究图景。我们使用了一项公开可得的肠道菌群数据集，该数据集来自一项针对30名健康对照（其中女性15名、男性15名）与28名ADHD患者（其中女性15名、男性13名）本科生开展的观察性病例对照研究，采用靶向16S（v3-4区，qPCR）测序技术。

我们首先开展了ADHD肠道菌群相关研究文献中常见的宏观分析，包括多样性分析、差异丰度分析与菌群组成分析，以观察现有研究结果的一致性或发现新的趋势。随后，我们采用SparCC相关性分析（p ≤ 0.01）构建健康对照与ADHD患者的微生物共现网络（Microbial Co-occurrence Networks, MCNs），以此估算双向生态相互作用。我们通过群落检测算法识别出存在相互协作关系的微生物类群簇及其质心，并通过中心性分析估算出对整体肠道生态最为关键的类群。最后，我们对研究结果进行总结，就该结果如何指导未来实验、优化本研究方法，以及该领域的一般性研究启示提出了若干猜想。