The exclusion criteria were the following: illiterate individuals or less than 8 years of education, any patient with disturbed conscious level, history or neurological signs of vascular or degenerative disorder, other psychiatric diseases, dementia (MMSE score below 24), epilepsy, patient with moderate or severe depression (according to Beck Depression Inventory), and using psychoactive drugs which included acetylcholinesterase inhibitors and included drugs that enhance brain cognitive functions or bias EEG activity. The gene discussed is ACHE; the disease is depressive symptom measurement.