A Resting-state Brain Function Study Of School-aged Child-ren With Attention-deficit/hyperactivity Disorder Based Onfunctional Magnetic Resonance Imaging

ObjectivesTo compare the difference of brain function in resting-state with two meth-ods, amplitude of low frequency fluctuation and regional homogeneity, between ADHD children and their comparable normal subjects based on the data acqui-red from resting-state functional magnetic resonance, and to investigate the cor-relations between these two indicators and age, gender, IQ, and symptom seve-rity in ADHD children, which can help clinicians to understand the neural pat-hological mechanism of behavioral and performance dysfunctions in ADHD ch-ildren.Methods18cases of6-12years old and drug-naive ADHD children (hereinafter referred to as case group)which correspond to the diagnostic code of DSM-IV,16males and2females, with the IQ range of81-108and mean value (95.77±10.79), were recruited in the present study. Among the ADHD patients, there are5cases of predominantly inattentive subtype(ADHD-I) and13cases of combined type(ADHD-C). Meanwhile18healthy control children (hereinafter referred to as the control group) which matches the ADHD group on age, gender, handedness,and IQ were also recruited in the study, and there were13males and5females, aged6-13years (mean9.60±2.06) old, with IQ range of91-122and mean value (100.93±8.33) in the control group. Whole brain resting state functional MRI data were acquired with1.5T MRI system,"DPARSF" software for data preprocessing, then go two sample t-test with the "REST" software, using regional homogeneity(ReHo) and amplitude of low frequency fluctuation(ALFF) as evaluation index, to compare the ALFF and ReHo differences between case and control group, as well as between the two subtypes and the control group, and then inter-subtypes. after that, the correlation analysis between ALFF or ReHo value and age, gender, IQ, and symptom severity in case group was carried out.Results(1) Comparations between case group and control group:compared to contr-ol group, the ALFF value of ADHD group decreased in the following brain region:the bilateral Cerebellum Posterior Lobe(t=4.36,3.88,z=-42,-39) and Left Pons(t=3.31,z=-33),but increased in right Precentral Gyrus; Meanwhile, the val-ue of ReHo decreased in following regions:left Medial Frontal Gyrus(t=4.90,z=30),Superior Frontal Gyrus(t=4.45,z=39), and left Precuneus (t=3.40,z=42), and increased in following regions:left Cerebellum Anterior Lobe(t=3.95,z=-12), le-ftCaudate(t=3.91,z=9), right Parahippocampa Gyrus(t=3.94,z=-18), left Precentral Gyrus(t=3.40,z=27), and right Middle Frontal Gyrus(t=3.68,z=57);(2) Comparations between ADHD subtypes and control group:compared to the control group, the ALFF value of ADHD-C children decreased in the left inferior frontal gyrus (t=3.622, z=-6), the left superior frontal gyrus (t=3.521, z=27), and the right middle frontal gyrus (t=4.495, z=42), but inc--reased in the right precuneus (t=-4.274, z=54) and the left middle frontal gyrus; The ReHo value of ADHD-C children decreased in the left parietal lob e (t=4.173, z=45),right frontal lobe (t=4.174, z=39), and the left su-perior frontal gyrus (t=4.346, z=84); The ALFF values of ADHD-I childre-n increased in the left occipital lobe (t=-5.542, z=9)compared to the contr-ol group; The ReHo value of ADHD-I children increased in the left occipital lobe (t=-5.542, z=9), the left middle frontal gyrus (t=-6.034, z=-12), the right parahippocampal gyrus(t=-5.442, z=-9) compared to the control gr-oup,but decreased in the left superior temporal gyrus (t=3.848, z=-39) an-d the left frontal lobe (t=5.358, z=39); (3) Comparations between the two ADHD subtypes:Compared to the AD-HD-I patients, the ADHD-C children showed decreased ALFF value in the left cuneus (t=-7.414,z=21) and the right middle occipital gyrus (t-4.885,z=6), a-nd showed decreased ReHo value in the left occipital lobe (t=-5.154,z=6)(4) Correlations between ReHo or ALFF value and demographic data or s-ymptom severity of ADHD patients:The ReHo or ALFF value has no statistic-ally significant correlation with age, gender, and IQ; In these brain areas belo-w, the ALFF value showed statistically significant correlation with ADHD-relat-ed total symptom scores:the cerebellar vermis (P<0.05, r=-0.758), the left pr-efrontal lobe(P<0.05, r=-0.645), the left caudate nucleus (P<0.05, r=-0.689); Th-e ReHo value showed statistically significant correlation with ADHD-related tot-al symptom scores in these brain areas:the left posterior cerebellar lobe (P<0.05, r=-0.735), the right posterior cerebellar lobe (P<0.05, r=0.699),the right parahippocampal gyrus (P<0.05, r=-0.824), left precuneus (P<0.05, r=-0.742), an-d the left precentral gyrus (P<0.05, r=0.683).Conclusions(1) Under resting state, school-aged ADHD children showed abnormal cerebral (frontal lobe, cerebellum, etc)activity compared to normal children, supporting the dysfunction hypothesis of the frontal lobe-cerebellar loops in default mode network (DMN);(2) ADHD symptom severity correlates with abnormal cerebral activity in the default mode network, and ALFF and ReHo values tended to show negativ-e correlation with symptom severity, suggesting that patients with more serious symptoms showed more decreased functional activities;(3) We did not find significantly correlation between ALFF or ReHo value with age, gender, and IQ, but we could not exclude the possibility of links b-etween them due to the small sample size of the study;(4) There are differences between ADHD-C subtype and ADHD-I subtype patients on ALFF or ReHo value in some local brain regions, suggesting that brain abnormalities of different ADHD subtypes may originated from different brain areas or different models of dysfunction.