Abstract
Background: The understanding of physiopathology and cognitive impairments in mood disorders requires finding objective markers. Mood disorders have often been linked to hypometabolism in the prefrontal dorsolateral cortex, and to GABAergic and glutamatergic neurotransmission dysfunction. The present study aimed to discover whether saccadic tasks (involving DPLFC activity), and cortical excitability (involving GABA/Glutamate neurotransmission) could provide neuropsychophysical markers for mood disorders, and/or of its phases, in patients with rapid cycling bipolar disorders (rcBD). Methods: Two rcBD patients were followed for a cycle, and were compared to nine healthy controls. A saccade task, mixing prosaccades, antisaccades, and nosaccades, and an evaluation of cortical excitability using transcranial magnetic stimulation were performed. Results: We observed a deficit in antisaccade in patients independently of thymic phase, and in nosaccade in the manic phase only. Cortical excitability data revealed global intracortical deficits in all phases, switching according to cerebral hemisphere and thymic phase. Conclusion: Specific patterns of performance in saccade tasks and cortical excitability could characterize mood disorders (trait-markers) and its phases (state-markers). Moreover, a functional relationship between oculometric performance and cortical excitability is discussed.
Highlights
Affective disorders are the most disabling of neuropsychiatric conditions, and one of the four leading causes of disability [World Health Organization (WHO), 2003]
The present study aimed to discover whether saccadic tasks, and cortical excitability could provide neuropsychophysical markers for mood disorders, and/or of its phases, in patients with rapid cycling bipolar disorders
There is a relative consensus in literature that cortical excitability may be a biological correlate of disease in mood disorders (Wassermann et al, 2001; Bajbouj et al, 2006b; Levinson et al, 2010)
Summary
Affective disorders are the most disabling of neuropsychiatric conditions, and one of the four leading causes of disability [World Health Organization (WHO), 2003]. In the present pilot study, we tested two tools: oculometry (saccadic tasks) and cortical excitability (via magnetic transcranial stimulation of the motor cortex), using a particular clinical paradigm: the follow-up of two patients suffering from rapid cycling bipolar disorders (rcBD). The present study aimed to discover whether saccadic tasks (involving DPLFC activity), and cortical excitability (involving GABA/Glutamate neurotransmission) could provide neuropsychophysical markers for mood disorders, and/or of its phases, in patients with rapid cycling bipolar disorders (rcBD). A saccade task, mixing prosaccades, antisaccades, and nosaccades, and an evaluation of cortical excitability using transcranial magnetic stimulation were performed. Conclusion: Specific patterns of performance in saccade tasks and cortical excitability could characterize mood disorders (trait-markers) and its phases (state-markers). A functional relationship between oculometric performance and cortical excitability is discussed
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