An in vitro method to diagnose or for identifying whether a patient presents a pathology or is at risk to develop a pathology related to an alteration of the ADARs catalyzed pre-mRNA editing mechanism, wherein this method comprising the following steps of: a) from a biological sample containing PBMC (Peripheral Blood Mononuclear Cells), said cells expressing the editing enzymes ADAR1a, ADAR1b and ADAR2 and the phosphodiesterase subtype 8A (PDE8A), - determining the editing profile of the PDE8A pre-mRNA measured in a cellular RNA extract obtained from said biological sample containing cells, and - determining the quantitative expression of said editing enzymes ADAR1a, ADAR1b and ADAR2; b) identifying whether said patient presents or is at risk to develop such a pathology by comparing the editing profile of the PDE8A pre-mRNA and the quantitative expression of ADAR1a, ADAR1b and ADAR2 obtained in step a) with control editing profile of the PDE8A pre-mRNA and quantitative expression of ADAR1a, ADAR1b and ADAR2 obtained for normal patients and/or for patients exhibiting pathologies related to an alteration of the mechanism of this mRNA editing, - wherein the editing profile of the PDE8A pre-mRNA measured in a cellular RNA extract obtained from said cellular extract, comprises at least the determination and/or the quantification of the isoforms B and the non-edited (ned) isoform, and - wherein said pathology is selected from the group consisting of psychiatric disorders, mental disorders, schizophrenia, depression, Bipolar disease, suicide, Mild Cognitive Impairement (MCI), Epilepsia, or Chronical pain syndromes. a) from a biological sample containing PBMC (Peripheral Blood Mononuclear Cells), said cells expressing the editing enzymes ADAR1a, ADAR1b and ADAR2 and the phosphodiesterase subtype 8A (PDE8A), - determining the editing profile of the PDE8A pre-mRNA measured in a cellular RNA extract obtained from said biological sample containing cells, and - determining the quantitative expression of said editing enzymes ADAR1a, ADAR1b and ADAR2; - determining the editing profile of the PDE8A pre-mRNA measured in a cellular RNA extract obtained from said biological sample containing cells, and - determining the quantitative expression of said editing enzymes ADAR1a, ADAR1b and ADAR2; b) identifying whether said patient presents or is at risk to develop such a pathology by comparing the editing profile of the PDE8A pre-mRNA and the quantitative expression of ADAR1a, ADAR1b and ADAR2 obtained in step a) with control editing profile of the PDE8A pre-mRNA and quantitative expression of ADAR1a, ADAR1b and ADAR2 obtained for normal patients and/or for patients exhibiting pathologies related to an alteration of the mechanism of this mRNA editing, - wherein the editing profile of the PDE8A pre-mRNA measured in a cellular RNA extract obtained from said cellular extract, comprises at least the determination and/or the quantification of the isoforms B and the non-edited (ned) isoform, and - wherein said pathology is selected from the group consisting of psychiatric disorders, mental disorders, schizophrenia, depression, Bipolar disease, suicide, Mild Cognitive Impairement (MCI), Epilepsia, or Chronical pain syndromes. - wherein the editing profile of the PDE8A pre-mRNA measured in a cellular RNA extract obtained from said cellular extract, comprises at least the determination and/or the quantification of the isoforms B and the non-edited (ned) isoform, and - wherein said pathology is selected from the group consisting of psychiatric disorders, mental disorders, schizophrenia, depression, Bipolar disease, suicide, Mild Cognitive Impairement (MCI), Epilepsia, or Chronical pain syndromes. <EOS>