Participants
Twenty-one euthymic patients who met DSM-IV criteria for bipolar I
disorder were recruited from the outpatient and inpatient wards of the
Department of Neurology and Psychiatry of the Policlinico Umberto I
Hospital – “Sapienza” University of Rome. Diagnoses were made by
well-trained psychiatrists according to DSM-IV TR criteria [2]. The
presence of a stable euthymic condition of at least one-month duration
was established according to Hamilton Depression Rating Scale (HAM-D;
[40]) scores (≤ 8) and of the Young Mania Rating Scale (YMRS;
[41]) scores (≤ 6). Exclusion criteria comprised: comorbid axis I
and II diagnosis; significant neurological or medical condition;
psychiatric hospitalization within the previous six months; substance or
alcohol abuse/dependence. All patients were under stabilized
psychotropic medications, which were prescribed according to the most
important international treatment guidelines for bipolar disorder
[42-44]. Twenty-one healthy volunteers with no current or past
psychiatric illness and no first-degree relative with affective disorder
were recruited and matched to patients on the basis of age, sex, and
education. Participants gave written informed consent to participate and
the Local Research Ethics Committee approved the study.