Abstract
Background: Altered sensorimotor gating has been demonstrated by Prepulse Inhibition (PPI) tests in patients with psychosis. Recent advances in signal processing methods allow assessment of neural PPI through electroencephalogram (EEG) recording during acoustic startle response measures (classic muscular PPI). Simultaneous measurements of muscular (eye-blink) and neural gating phenomena during PPI test may help to better understand sensorial processing dysfunctions in psychosis. In this study, we aimed to assess simultaneously muscular and neural PPI in early bipolar disorder and schizophrenia patients. Method: Participants were recruited from a population-based case-control study of first episode psychosis. PPI was measured using electromyography (EMG) and EEG in pulse alone and prepulse + pulse with intervals of 30, 60, and 120 ms in early bipolar disorder (n = 18) and schizophrenia (n = 11) patients. As control group, 15 socio-economically matched healthy subjects were recruited. All subjects were evaluated with Rating Scale, Hamilton Rating Scale for Depression, and Young Mania Rating Scale questionnaires at recruitment and just before PPI test. Wilcoxon ranked sum tests were used to compare PPI test results between groups. Results: In comparison to healthy participants, neural PPI was significantly reduced in PPI 30 and PPI60 among bipolar and schizophrenia patients, while muscular PPI was reduced in PPI60 and PPI120 intervals only among patients with schizophrenia. Conclusion: The combination of muscular and neural PPI evaluations suggested distinct impairment patterns among schizophrenia and bipolar disorder patients. Simultaneous recording may contribute with novel information in sensory gating investigations.
Highlights
Patients with bipolar disorder (BP) and patients with schizophrenia (SZ) show overlaps of symptoms and deficits [1–6] that challenge the dichotomy proposed in Kraepelin’s original classification of manic-depressive psychosis and dementia praecox [7], or the affective and non-affective psychosis of more recent diagnostic classifications
As the pontine reticular nucleus (PnC) on the rapid pathway may be inhibited by the pedunculopontine tegmental nucleus (PPN) in the slower pathway, it has been hypothesized that this slower circuit activation by the PP inhibits the startle response evoked by P, resulting in the prepulse inhibition (PPI) phenomenon
Use of atypical antipsychotic medication was different between BP and SZ
Summary
Patients with bipolar disorder (BP) and patients with schizophrenia (SZ) show overlaps of symptoms and deficits [1–6] that challenge the dichotomy proposed in Kraepelin’s original classification of manic-depressive psychosis and dementia praecox [7], or the affective and non-affective psychosis of more recent diagnostic classifications Both are heritable [8], respond to antipsychotics [9,10], share common genetic causes [11,12], illness course and cognition impairments [13–16], and there is interchange in diagnosis in a fraction of these patients [17]. The most common way of evaluating sensory-motor gating impairments is the muscular prepulse inhibition (PPI) test This test evaluates the eye-blink startle reflex reduction when a weak Prepulse (PP) stimulus precedes an intense Pulse (P) stimulus by few milliseconds [19–23]. This measure recruits the acoustic startle rapid response pathway, constituted by the cochlear root nucleus, caudal pontine reticular nucleus (PnC), and motoneurons [24]. Simultaneous recording may contribute with novel information in sensory gating investigations
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