An investigation of the association between gender, diagnosis, cognitive deficits and N100 amplitude in people with first-episode psychosis.

Proposal details

Title: An investigation of the association between gender, diagnosis, cognitive deficits and N100 amplitude in people with first-episode psychosis.
Research Area(s): Schizophrenia and Allied Psychoses
Background: Gender differences Recent research in schizophrenia and other psychotic disorders has used event-related potentials (ERPs) to gain a better understanding of the neuropsychological deficits and the underlying biological aetiology of these diseases. For example, studies investigating differences in amplitude of ERPs in patients with schizophrenia have repeatedly shown a suppression of the P300, a component which occurs at 300ms post stimulus and is associated with attention-dependent processing (Ford & Roth, 2004; Kogoj, Pirtosek, Tomori & Vodusek, 2004). A suppressed P300 response is also evident in first-degree relatives of chronic schizophrenic patients, suggesting that it may be a reliable biological marker (Blackwood, 2000). Likewise, the amplitude of the N100 has also been identified as a possible biological marker (Brown, Gonsalvez, Harris, Williams & Gordon, 2002). However, the findings regarding N100 amplitudes, which occur in the pre-attentive stage before the P300, are less defined or consistent. One study demonstrated that the reduction of N100 amplitudes found in chronic schizophrenic patients was also present in first-episode psychosis (Brown et al., 2002). However, no differences were found between first-episode patients and healthy controls in a study using never-medicated subjects (Valkonen-Korhonen, Purhonen, Tarkka, Sipila, Partanen, Karhu & Lehtonen, 2003). Another study identified that N100 reduction is generally found in studies with male participants (eg. Brown et al, 2002) but is absent in studies with high male/female ratios (Sumich, Harris, Flynn, Whitford, Tunstall, Kumar, Brammer, Gordon & Williams, 2006). No study has yet investigated the possibility of inherent neurophysiological differences between males and females with first-episode psychosis. Differences in diagnosis of first episode psychosis N100 research has been largely focused on patients within schizophrenia and schizophrenic-type categories (Brown et al, 2002; Sumich et al, 2006), although some studies have included patient samples with other types of psychosis such as bipolar or delusional disorder (eg. Valkonen-Korhonen et al, 2003). Consequently, no studies have reported on N100 amplitude in different subtypes of first-episode psychosis. Such an investigation will help to clarify whether a reduction in amplitude of the N100 is characteristic of first-episode schizophreniform psychosis, or if not, how it may or may not be different to other types of first-episode psychoses. For the same reasons, differences in topography and laterality are also of interest. Cognitive deficits Neurophysiological deficits are common in schizophrenia (eg. Sumich et al., 2006), and an association has been found between reduced N100 amplitude and deficiencies in attentional processes (Valkonen-Korhonen et al., 2003). The proposed study will investigate the associations between N1 amplitude, neuropsychological deficits, gender, and diagnosis.
Aims: To investigate the association between gender, diagnosis, cognitive deficits and N100 amplitudes in people with first-episode psychosis.
Method: In order to carry out the study, the following data is required: -Amplitudes and latencies of the N100 in people with the first-episode psychosis dataset. -Amplitudes and latencies of the N100 in control subjects matched for age, gender and years of education. -Demographic, diagnostic and neuropsychological data for the subjects with first-episode psychosis. The N100 data is held by BRC. The other data is held by the BRC First Episode Psychosis Group. All members of this group who have contributed to the First Episode Psychosis database will be encouraged to participate in this study.