Classification of schizophrenia patients based on resting-state functional network connectivity

Abstract

There is a growing interest in automatic classification of mental disorders based on neuroimaging data. Small training data sets (subjects) and very large amount of high dimensional data make it a challenging task to design robust and accurate classifiers for heterogeneous disorders such as schizophrenia. Most previous studies considered structural MRI, diffusion tensor imaging and task-based fMRI for this purpose. However, resting-state data has been rarely used in discrimination of schizophrenia patients from healthy controls. Resting data are of great interest, since they are relatively easy to collect, and not confounded by behavioral performance on a task. Several linear and non-linear classification methods were trained using a training dataset and evaluate with a separate testing dataset. Results show that classification with high accuracy is achievable using simple non-linear discriminative methods such as k-nearest neighbors (KNNs) which is very promising. We compare and report detailed results of each classifier as well as statistical analysis and evaluation of each single feature. To our knowledge our effects represent the first use of resting-state functional network connectivity (FNC) features to classify schizophrenia.

Keywords: classification; functional network connectivity; independent component analysis (ICA); resting-state fMRI; schizophrenia.

Figure 1

The proposed approach. The pink blocks on the top show the feature extraction steps. The statistical analysis box (green) is not part of the classification approach. The light green blocks describe the classification stage. Orange clouds indicate the corresponding figures and tables in the Results section.

Figure 2

Spatial maps of the nine selected IC components.

Figure 3

Left: Mean of correlation pairs for controls and patients. Right: T-value of each correlation pair resulted from student t-test with p-value threshold of 0.05 corrected for FDR. Black circles indicate the pairs surviving the t-test.

Figure 4

Left: Mean correlation difference between control subjects and patients (control-patient). Right: T-value resulting from two sample t-test with p-value threshold of 0.05 corrected for FDR. Stars show pairs that survived the paired t-test.

Figure 5

Fisher's decision tree using full set of features. This tree includes 8 features in 10 nodes.

Figure 6

Information gain decision tree using full set of features. This tree includes six features in six nodes.