Introduction
Bipolar Disorder (BD) is a chronic and recurrent mental illness, found
in approximately 3% of the general population [1]. Typically, BD is
characterized by extreme changes in mood polarity (mania and depression)
with intervening periods of euthymia [2]. Growing evidence has
revealed that patients with BD may experience poor social functioning in
several areas such as such as independent living, interpersonal
relationships, occupational and educational achievement, recreational
enjoyment, and sexual activity [3], and that these dysfunctions
persist even during the clinical remission of symptoms or euthymia
[4]. Social difficulties have also been demonstrated in laboratory
tasks. Euthymic BD patients can be impaired at recognising faces and
identifying facial expressions of emotion [5-8]. Behavioural
deficits in the recognition and naming of facial emotions may be
mediated by perturbations within the neural circuit including the
ventral visual pathway, amygdala and ventrolateral prefrontal regions
[9-11]. Consistent with this view, using affective faces tasks,
previous studies have shown amygdala dysfunctions in maniac bipolar
patients [12-14] and a dysfunction of the ventrolateral prefrontal
cortex during both mania [12, 15, 16] and euthymia [17-20].
Given the associations between these brain areas and eye gaze
processing, the aim of the present study was to explore the extent to
which euthymic BD patients may show anomalies in the processing of
eye-regions of the face. In particular, two important aspects of
eye-gaze processing were assessed: the ability to infer the mental state
and intention of others from the eyes (reading the mind in the eyes) and
the tendency to follow the direction of another individual’s gaze
(social attention).