Controls: Participants (n = 96; age: 52.2 ± 16.8 years; range: 19–80 years; 63 females) undergoing EEG due to indications unrelated to neuropsychiatric diseases. Exclusion criteria for this group included diagnosis of depression or schizophrenia, bipolar disorder, substance abuse, psychiatric or general medical conditions requiring hospitalization, history of epilepsy or conditions requiring anticonvulsants, ECT, vagal nerve stimulation, or transcranial magnetic stimulation (TMS), history of traumatic brain injury and history or imaging findings of cerebrovascular diseases including ischaemic and haemorrhagic stroke.
Depression: Participants with a diagnosis of major depressive disorder (MDD) hospitalized during the index time. This diagnosis had been established by two senior psychiatrists according to DSM-IV and DSM-V criteria following a psychiatric interview where the severity of depression was found to be at least moderate. In addition, the participants (n = 28; age: 69.7 ± 14.8 years; range: 33–91 years; 20 females) had to have had at least 1 previous major depressive episode, prior to age 30—namely, the index episode was a recurrent one.
Schizophrenia: Diagnosis of schizophrenia had been established by two senior psychiatrists according to the ICD-10 criteria. In addition, the participants (n = 42; age: 41.4 ± 16.8 years; range: 18–76 years; 15 females) had to be hospitalized during the index time.
