Intelligent diagnosis of depression by integrating genetic algorithm and graph neural network
Objective Depression is currently one of the most common neuropsychiatric disorders in the world.However,its pathophysiological mechanisms are still unclear.The diagnosis of depression in clinical practice typically depends on neuropsychological scores and treatment responses,lacking objective evaluation tools,resulting in low consistency in diag-nosis.In recent years,an increasing number of people have begun to use machine learning technology to extract imaging biomarkers for the intelligent diagnosis of depression due to the capability of functional magnetic resonance imaging to pro-vide in vivo brain function and structural information.The brain network-based model has remarkable potential as an imag-ing marker for effectively distinguishing depression from normal controls.Graph neural networks(GNNs)are highly suit-able for graph classification tasks because they directly acquire graph structure information and maintain the topological characteristics of the graph during task execution.However,most GNN studies only model a single space(sample or fea-ture space),and the aggregation of GNN information can lead to over-smooth effects,resulting in poor model classification performance.This study aims to integrate multiple feature space information and propose a multispace fusion algorithm for the intelligent diagnosis of depression patients.Method Leave-one-site cross-validation(LOSCV)is used to ensure the gen-eralization of the model.The data are first preprocessed,and then a brain network is constructed using Pearson-related functional connectivity methods.The entire algorithm is mainly based on a genetic algorithm(GA),where the fitness func-tion is a classification algorithm based on a graph convolutional network(GCN).The solution space searched by GA is the similarity between the subject networks.The main steps of GA are as follows:1)Set the search range of the solution space[0.05,0.7];2)Generate an initial population;3)Based on LOSCV,GCN is used to classify the data,with the F1 value as the target value of the fitness function,and the threshold with the best fitness is finally retained(representing A*);4)Generate new populations through selection,crossover,and mutation operations(representing A);5)Compare A with A*.If the fitness value of A is better than A*,then A replaces A*;6)Determine whether the number of iterations for updating the population has reached the preset value.If not,then proceed to step 3 and continue executing the algorithm;if the threshold is reached,then the algorithm ends.The GA has a chromosome length of 8 bits and a threshold of 20 iterations.This paper aims to determine the similarity threshold between individuals with the highest classification capability in the population network.The GCN module comprises two networks connected in series:one mainly obtains information regard-ing the feature space of the brain network of a single subject,while the other network takes the subject as a node in the net-work.All subjects form a network to extract information from the sample space.The classification of a certain subject can be achieved through the joint learning of two levels of GCN.The two-level GCN architecture mainly includes f-GCN and p-GCN,and the basic ideas for constructing each architecture are as follows:f-GCN is a potential information representa-tion for learning the connectivity relationships of each brain region and transforming it into a highly efficient information rep-resentation for each brain network.F-GCN uses GCN to learn the embedding representation of a single brain region and then uses Eigenpooling to embed all brain region nodes into a single supernode to represent the information representation of the entire brain network.Eigenpooling is a pooling method in graph convolution neural network(GCN),which uses the eigenvectors of the Laplacian matrix to represent the information of nodes,transforms the original graph nodes into coordi-nates in the feature space,and associates each node with a specific number of high-energy eigenvectors,which are deter-mined by the eigenvalues of the Laplacian matrix.The feature vector represents the position of a node in the feature space,and its corresponding feature values indicate node importance.P-GCN constructs a topological structure based on the rela-tionship between subject brain networks and the representation of graph information acquired by f-GCN.The graph convolu-tional kernel aggregates the information representations of adjacent node entities of the subject and further reduces the dimensionality of the node information representation through graph pooling to generate the current supernode information representation.In this case,the hypernode represents the information of the entity as a whole.The graph information of the entire subject can be accurately represented through this super node,and the parameters of the f-GCN and p-GCN can be jointly updated through backpropagation to improve recognition accuracy.A scaled exponential similarity kernel is used for p-GCN to determine the similarity between samples.Result All data came from the REST-meta-MDD project,and a total of 1160 functional magnetic resonance imaging data from 10 sites(male 434,female 726)were included in this experiment.The experiment is a comparison of four representative algorithms of different types.The algorithm achieved the highest accuracy of 64.27％,which is 4.47％higher than the second-place support vector machine(SVM).Based on the Brain-NetCNN method,the accuracy is only 56.69％,demonstrating the worst classification performance.The accuracy of the Graphormer is 57.43％,and the hierarchical GCN also adopts the fusion of two networks,resulting in a classification accu-racy of 58.28％.The sample similarity threshold also impacts the final result,with an interval of 0.4-0.5 during identifi-cation of the optimal solution.Conclusion The intelligent diagnosis framework for depression based on GA and GCN pro-posed in this article combines the advantages of traditional and deep learning models.The results show that the proposed algorithm is not only superior to traditional machine learning algorithms(such as SVM),but also better than several main-stream GCN algorithms,with good generalization.This algorithm is likely to provide important information for clinical depression diagnosis in the future.
major disorder depressiongraph convolutional network(GCN)intelligent diagnosisfusion algorithmindi-vidual similarity
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