肥胖與大腦結構網路改變的關係及其對心理健康之影響

目的： 肥胖是一種複雜的多因子疾病，且被認為是一種全球性的流行病。過去文獻指出肥胖會對精神疾病患者產生不同的影響，因此我們假設肥胖會改變大腦的結構，並造成大腦傾向於情緒和認知紊亂。在本研究中，我們比較肥胖受測者和健康對照組之間大腦灰、白質結構/網絡的變化，並進一步針對肥胖受測者及健康對照組做一些測試以取得臨床精神及認知量表，探討擴散指標和量表之間的相關性。材料與方法： 本研究一共招募20名肥胖受測者(BMI=37.9±5.2)和30名健康對照組(BMI=22.6±3.4)接受非侵入性擴散張量(Diffusion Tensor Imaging, DTI)和通用擴散波數取樣磁振造影(Generalized q-sampling imaging, GQI)的掃描。並使用圖形理論分析(Graph theoretical analysis, GTA)和基於網絡的統計分析(Network-based statistical analysis, NBS)評估兩組之間的結構性網路連結差異。此外，我們將擴散指標和身高體重指數、焦慮憂鬱量表、愛荷華賭局作業、視覺偵測作業及停止訊號反應時間等量表做多元回歸的分析，以探討肥胖對於情緒及認知功能造成之影響。研究結果： 與健康對照組相比，肥胖受測者的擴散指標在內囊後肢、放射冠和上縱束顯著降低。此外，肥胖受測者容易產生焦慮和抑鬱的感覺，且有認知表現下降的現象。而在大腦結構性網路連結的部分，肥胖受測者的群聚係數(Clustering coefficient, C)、傳遞性(Transitivity)、局部效率(Local efficiency, Elocal)和全局效率(Global efficiency, Eglobal)的拓樸參數均顯著降低。結論： 肥胖和大腦結構和功能有高度相關性，根據本研究結果，我們可以透過肥胖個體中受到影響的大腦腦區及結構性網路連結異常來進一步擴展知識，並在臨床治療肥胖症上提供些微的貢獻。

PURPOSE: Obesity is a complex and multifactorial disease identified as a global epidemic. Convergent evidence indicates that obesity differentially influences patients with neuropsychiatric disorders providing a basis for hypothesizing that obesity alters brain structure and function associated with the brain''s propensity toward disturbances in mood and cognition. Herein, we characterize alterations in brain structures and networks among obese subjects (ie, body mass index [BMI] ≥ 30 kg/m2) when compared with non-obese controls.PATIENTS AND METHODS: We obtained noninvasive diffusion tensor imaging and generalized q-sampling imaging scans of 20 obese subjects (BMI=37.9±5.2) and 30 non-obese controls (BMI=22.6±3.4). Graph theoretical analysis and network-based statistical analysis were performed to assess structural and functional differences between groups. We additionally assessed for correlations between diffusion indices, BMI, Hospital Anxiety and Depression Scale (HADS), Iowa Gambling Task (IGT), Visual Probe Task (VPT), and Stop-signal Reaction Time (SSRT).RESULTS: The diffusion indices of the posterior limb of the internal capsule, corona radiate, and superior longitudinal fasciculus were significantly lower among obese subjects when compared with controls. Moreover, obese subjects were more likely to report anxiety and depressive symptoms. Topological measures of clustering coefficient (C), local efficiency (Elocal), global efficiency (Eglobal), and transitivity were significantly lower among obese subjects. Similarly, three sub-networks were identified to have decreased structural connectivity among frontal-temporal regions in obese subjects compared with non-obese controls.CONCLUSION: We extend knowledge further by delineating structural interconnectivity alterations within and across brain regions that are adversely affected in individuals who are obese.