2.1 Subjects
This was a cross-sectional study conducted at the Wuhan Mental Health Center (WMHC) (Wuhan, Hubei Province, China). We recruited three distinct groups of participants: EBP, their FDR, and HC. EBP and FDR were recruited from outpatients and their first-degree relatives in WMHC, while HC was recruited from local communities in Wuhan. Only one first-degree relative of each bipolar disorder patient will be included in the study. Due to the fact that cognitive function may be affected by age and education, precedence was given to siblings of the same gender, if available, followed by siblings of a different gender, and then biological parents or children. Prior to participation, written informed consent was obtained from all participants. The trial was examined and authorized by the Ethics Committees in WMHC. This study comprised a total of 243 participants, including 81 EBP, 81 FDR, and 81HC. All participants in this study are Han Chinese.
EBP group inclusion criteria: 1 who meets the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnostic criteria for bipolar I disorder; 2 Hamilton Depression Scale 17-item (HAMD) (Hamilton et al., 1960) score< 8; Young Mania Rating Scale (YMR) (Young et al., 1978) score<6; 3 absence of affective symptom episodes in the three months prior to enrolment; 4 age 18–60 years; 5 years of education ≥9;6 Han Chinese.
FDR group consisted of the enrolled patients’ first-degree relatives. Inclusion criteria: 1 not fulfilling the diagnostic criteria established by DSM-5 for bipolar I disorder or other psychiatric disorders; 2 age 18-60 years; 3 years of education ≥9; 4 Han Chinese. Exclusion criteria include (1) people with a history of organic brain disorder or traumatic brain injury, (2) those with severe physical illness, and (3) those with a physical disability or visual and hearing impairment.
Healthy control inclusion criteria: 1. no history of mental disease or major physical illness; 2. no history of mental illness in the family. 3 age 18-60 years; 4 years of education ≥9 years; 5 Han Chinese. The same exclusion rules applied to the FDR group.
Two attending psychiatrists administered The Chinese version of the Mini-International Neuropsychiatric Interview (MINI) (Sheehan et al., 1998) to all participants in order to clarify the diagnosis of bipolar disorder and rule out the presence of psychiatric disorders in first-degree relatives and healthy controls. EPD was also evaluated using the A Rating Scale for Extrapyramidal Side Effects (RSESE)33 to rule out drug-induced extrapyramidal side effects.
All participants completed a battery of questionnaires covering general information, family and personal history of mental and physical problems, degree of education, handedness, and somatic diseases.