Neuropsychological correlates of P50 sensory gating in patients with schizophrenia Eva María Sánchez-Morla a, b, e, ⁎, José Luis Santos a , Ana Aparicio a , María Ángeles García-Jiménez c , Carmen Soria c , Celso Arango d a Department of Psychiatry, Hospital Virgen de la Luz, Cuenca, Spain b Department of Psychiatry, Hospital Universitario de Guadalajara, Guadalajara, Spain c Neurophysiology Unit, Hospital Virgen de La Luz, Cuenca, Spain d Child and Adolescent Department of Psychiatry, IsSGM, Hospital General Universitario Gregorio Marañón, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain e School of Medicine, University of Alcalá, Madrid, Spain abstract article info Article history: Received 28 June 2012 Received in revised form 10 September 2012 Accepted 21 October 2012 Available online xxxx Keywords: P50 Schizophrenia Cognition Evoked potential recordings Neuropsychological measures Impaired inhibition of P50 cerebral evoked response is one of the best validated endophenotypes in schizophre- nia. There are controversial data on the relationship between P50 evoked potential deficit and measures of cog- nitive function in schizophrenia. A comprehensive clinical and neurocognitive assessment plus an evaluation of P50 sensory gating was performed in 160 schizophrenia patients and 64 controls. Neurocognitive scores from each cognitive domain were converted to demographically-adjusted T-scores (age, gender, and years of educa- tion) for all study participants. The relationship between P50 and neurocognitive variables was assessed via para- metric and nonparametric correlations and categorical strategies: we compared neuropsychological test scores in patients and controls in the lowest P50 quartile vs. the highest. Controls had better performance than schizo- phrenia patients in all cognitive domains. Schizophrenia patients had significantly higher P50 ratios than con- trols, and no significant correlation was found between P50 gating measures and neuropsychological test scores in schizophrenia patients or healthy controls. Moreover, no differences in neurocognitive performance were found between subjects in the lowest P50 ratio quartile vs. the highest in healthy controls or patients with schizophrenia. We concluded that there is no evidence of an association between P50 ratio and cognitive measures in schizophrenia patients, and this seems to be also the case in healthy controls. © 2012 Elsevier B.V. All rights reserved. 1. Introduction P50 wave is a preattentional component of the middle latency audi- tory evoked potentials (MLAEPs) recorded about 50 ms after the presentation of an auditory stimulus. MLAEPs decrease in amplitude when a second stimulus (S2), identical to the first stimulus (S1), is delivered about 500 ms later (Turetsky et al., 2007). This amplitude suppression of the wave evoked by the second stimulus (S2) reflects a sensory gating mechanism aimed at protecting against information overload (Braff and Geyer, 1990). Individuals with schizophrenia are long known for having relatively less suppression of P50 amplitudes which has been related to the inability of the central nervous system to filter irrelevant sensory inputs (Adler et al., 1982). A P50 deficit sug- gests that there is an abnormality that affects early stages of information processing (Boutros et al., 2004). Subsequent studies have confirmed that P50 suppression deficits are already present in early stages of schizophrenia (Myles-Worsley et al., 2004; Brockhaus-Dumke et al., 2008a; Hong et al., 2009), in both acutely ill and more stable schizophrenia outpatients (Bramon et al., 2004; de Wilde et al., 2007; Patterson et al., 2008; Thaker, 2008) as well as in their first degree rel- atives (Olincy et al., 2010; Turetsky et al., 2012). The majority of studies have failed to demonstrate a significant relationship between P50 sen- sory gating and clinical symptoms (Adler et al., 1990; Jin et al., 1998; Boutros et al., 2004; Potter et al., 2006; Boutros et al., 2009; Santos et al., 2010). Despite the fact that sensory gating as described by Venables (1964) was closely related to the phenomenon of cognitive impair- ment, in some patients who could not inhibit irrelevant stimuli and were overloaded by the environment, the reality is that few studies have examined whether there is any relationship between P50 and different domains of neuropsychological performance in patients with schizophrenia. P50 suppression abnormalities have been related to attention deficits assessed by the Gordon Diagnostic System ver- sion of the Continuous Performance Test (Erwin et al., 1998) and other attention tests (Cullum et al., 1993). Measures of processing speed have also been linked to P50 gating (Erwin et al., 1998). How- ever, it is unclear whether P50 suppression deficits are linked to poorer performance in working memory and executive tests. Thus, correlation was found between P50 ratio and digit span backward (Cullum et al., 1993) although this finding could not be replicated (Erwin et al., 1998). P50 gating deficits have not been related to Schizophrenia Research xxx (2012) xxx–xxx ⁎ Corresponding author at: Department of Psychiatry, Hospital Universitario de Guadalajara,C/Hermandad Donantes de Sangre, s/n. 19002. Guadalajara, Spain. Tel.: +34 949209200. E-mail address: emsanchez@sescam.jccm.es (E.M. Sánchez-Morla). SCHRES-05169; No of Pages 5 0920-9964/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.schres.2012.10.017 Contents lists available at SciVerse ScienceDirect Schizophrenia Research journal homepage: www.elsevier.com/locate/schres Please cite this article as: Sánchez-Morla, E.M., et al., Neuropsychological correlates of P50 sensory gating in patients with schizophrenia, Schizophr. Res. (2012), http://dx.doi.org/10.1016/j.schres.2012.10.017