Previous studies reported an association between weak habituation of skin conductance
Previous studies reported an association between weak habituation of skin conductance orienting response and psychosis proneness. ideas. These results suggest that decreased habituation of arousal, NRG1-induced AKT phosphorylation, and anxiety are related to delusional ideation in the general population. gene are associated with schizophrenia and bipolar disorder, although the evidence is not conclusive.15,16 Postmortem studies have revealed altered expression of different isoforms of NRG1 in the brain of patients with schizophrenia, but these alterations are not consistently linked to functional polymorphisms.17 Some of these genetic variants have been linked to decreased brain activation during cognitive tasks and to increased risk of psychosis conversion in people who displayed subclinical psychosis-like symptoms (at-risk mental state).18,19 Sei et al10 demonstrated that NRG1-induced migration of B lymphoblasts of patients with schizophrenia is significantly decreased compared with control individuals. This impaired migration was related to reduced NRG1-stimulated AKT phosphorylation in the patients and was associated with polymorphisms of the and catechol-(Fourth Edition) Axis I disorders (SCID-CV).21 Individuals with psychiatric disorders, including psychoactive substance misuse, were excluded from the study. General intellectual functions were assessed by the revised version of the Wechsler Adult Intelligence Scale (WAIS-R).22 All participants gave written informed consent, and the study was approved by the local ethics board. Assessment of Delusional Ideation and Emotional Symptoms Delusional ideas were measured using the Peters et al. Delusion Inventory (PDI),23 which is a self-report instrument consisting of modified items from the Present State Examination.24 The PDI assesses delusional conviction, preoccupation, and distress. The original scale consists of 40 items, which are divided into 8 categories: (1) delusions of control; (2) Clindamycin palmitate HCl supplier misinterpretations, misidentification, and delusions of reference; (3) delusions of persecution; (4) expansive delusions; (5) delusions concerning various types of influence and primary delusions; (6) other delusions (delusions related to body image and smell); (7) simple delusions based on guilt, depersonalization, hypochondriasis; (8) thought reading, insertion, echo, broadcast. First, the participant was asked a yes-no question (Do you ever feel as if people seem to drop hints about you or say things with a double meaning? or Do you ever feel as if electrical devices such as computers can influence the way you think?). Participants were asked to fill the conviction, preoccupation, and distress scales only for the statements that they endorsed (yes response). In the case of a no response, they were asked to proceed to the next question without filling in the scales, and a score of 0 was given. Each dimension was represented by a 5-point Likert scale (from Not at all distressing [point 1] to Very distressing [point 5] for distress; from Hardly ever think about it [point 1] to Think about it all the time [point 5] for preoccupation; and from Don’t believe it’s true [point 1] to Believe it is absolutely true [point 5] for conviction). In the present study, the 21-item version of the PDI was Clindamycin palmitate HCl supplier used25. The Cronbach was .84, indicating a good internal consistency. The dependent measure was the total PDI score, which was the sum of the conviction, preoccupation, and distress subscales. Anxiety Clindamycin palmitate HCl supplier and depression were measured by the Beck Anxiety Inventory (BAI)26 and by the Beck Depression Inventory (BDI)27, respectively. Orienting Response To measure the orienting response, the classic method of Venables and Christie28 was implemented in a modified version. An in-house made instrument was used that was linked to a HP workstation. Silver/silver chloride electrodes were placed on the index and LW-1 antibody middle fingers of the dominant hand of the participants. The duration of baseline recording without any stimulus was 5 minutes. After the baseline recording, the stimulus presentation began. Stimuli were 10 consecutive tones presented binaurally through headphones (80 dB, 800 Hz). The interstimulus interval varied between 40 and 80 seconds. The skin conductance response was recorded during the baseline period and during the orienting response to the tones. The orienting response was measured in a latency window of 0C5 seconds after stimulus offset. Clindamycin palmitate HCl supplier The amplitude threshold was 0.05 S. Nonrespondents were excluded from the experiment (12 volunteers not included in the sample description). To define individuals with weak and strong adaptation, the habituation index was calculated for each participant. To obtain the index, Clindamycin palmitate HCl supplier the orienting response amplitude of the third trial was subtracted from the amplitude of the first trial, given that habituation is the most pronounced during the first 3 trials.6 Positive values of the index indicate normal (strong) habituation, whereas 0 or negative values.