The goal of this observational study is to learn about The immune cell landscape of peripheral blood mononuclear cells in children with ADHD compared to typically developing controls. The main question it aims to answer are: 1.Testing the differences in immune cell subpopulations, protein expression and signaling pathways and cell subsets between two groups 2. Exploring the correlations between immune function in PBMC and resting-state brain functional networks in children with ADHD.

Participants will be taken peripheral blood about 5 ml , cognitive assessment including Intelligence testing, Stroop color-word test and Trail making test, clinical interview and brain structural and functional MRI.

3.1 Research Content Peripheral blood mononuclear cells of ADHD children and control group were taken, and 41 protein Marker on the cell surface was detected and analyzed by mass spectrometry flow cytometry (CyTOF) technology to draw a detailed map of ADHD immune cells, so as to explore the differences in protein expression level and subgroup distribution of immune cells between ADHD children and normal children. To evaluate the clinical symptoms, cognitive function, head MRI structure and resting state data of children with ADHD, and explore the correlation between immunophenotype and symptom score, cognition and brain structure.

3.2 Research Scheme 3.2.1 Collection of general and demographic data Demographic and clinical data, including name, age, sex, height, weight, age of first onset, course of disease, treatment, family history, past history and personal history, were collected by self-designed general situation scale.

3.2.2 Clinical evaluation The primary Clinical diagnosis was made by child psychiatrists with the title of attending psychiatrist or above through non-prescriptive clinical Interview, and the Clinical Diagnostic Interview Scale prepared by the American Working Group on Childhood Disorders was used. CDIS were conducted to evaluate ADHD classification, comorbidities, classification, comorbidities and clinical symptoms.

3.2.3 Core symptoms of ADHD ADHD-RS symptom assessment questionnaire was used to assess the severity of symptoms. The sum of scores of items in the attention deficit dimension is the attention deficit score, the sum of scores of items in the hyperactivity and impulsivity dimension is the score of hyperactivity impulse, and the sum of scores of all items is the score of the full scale. The higher the score, the more severe the symptoms.

3.2.4 Wechsler Intelligence test The Chinese children's Intelligence Scale (the third edition) was used to assess the IQ of the children.

3.2.5 Stroop color word naming test The test is divided into four parts. Part 1 asked the subjects to read red yellow green blue black character 6 Part 2 asked to name 30 red yellow green blue block colors; The third part requires reading 30 words whose meaning is inconsistent with the color of the print; Part 4 requires 30 read colors for word meaning and print color inconsistencies. The calculation indicators are: the completion time and the number of errors for each part. The results of part 1 and 2 reflect the ability of immediate attention; The time of Part 3 subtracts the time of Part 1 when the color interferes; The time of Part 4 minus the time of Part 2 is when the word is disturbed.

3.2.6 Trail making test (TMT) It is divided into A and B. In Formula A, the subjects were presented with numbers ranging from 1 to 25 randomly distributed, and were asked to connect the numbers accurately and quickly in an increasing order of 1-2-3 digits. The calculation measures the time and number of errors of the operation: reflects the visual spatial scanning and writing ability. In Formula B, the numbers 1-13 and letters A-L were distributed randomly and irregularly, and the subjects were required to accurately and quickly connect the numbers and letters in the cross order of 1-A-2-B-3-C. The calculation index was operation time and number of errors: the speed of reaction operation and the quality of completion. Use time B - time A: The ability to reflect the conversion of the subject.

3.2.7 The brain MRI structure and resting state data of subjects were collected High-resolution brain structure images were obtained using the Magnetization Prepared Rapid Acquisition Gradient-echo (MPRAGE) sequence with the following parameters: TR/TE= 7.1/2.9ms; sli-ces=146; Thickness =1 mm; Turnover Angle =8°; Matrix =256×256; Field of view =260×260 mm2; Voxel size 1*1*1mm.

Fmri images were collected by spin-echo-echo planar imaging (SE-EPI). The specific parameters were as follows: TR/TE=1800/30ms, section =28, thickness =4mm; Matrix =64×64, FOV=240×240 mm2, gap =0.8mm; Time point =180.

Inclusion Criteria:

Clinical diagnosis of ADHD； Children with an IQ≥70； Both parents are Han； Agree to take venous blood with informed consent；

Exclusion Criteria:

Schizophrenia, mood disorder, autism, mental retardation； Obvious physical and nervous system abnormalities；

Children and teenagers ages 6-12 years