تغییرات شناختی در بیماران مبتلا به مرحله حاد روان پریشی : بررسی اثر استفاده از مواد مخدر غیر قانونی

Illicit drug use may influence cognition in non-affective psychosis. Previous studies have shown better cognition in psychosis with illicit drug use as compared to psychosis only. Possibly, illicit drug using patients have more transient drug-related cognitive deficits. Thus, the aim of the present study was to examine cognitive change the first weeks after admission to a psychiatric emergency ward, expecting more cognitive improvement at follow-up in the illicit drug group as compared to psychosis only. Patients with acute non-affective psychosis with (26%) and without illicit drug use were examined at baseline (n=123) and follow-up (n=67), with alternative forms of the Repeatable Battery for the Assessment of Neuropsychological Status. Latent Growth Curve models, controlling for cognition at baseline and age differences between the groups, were used to analyze cognitive change. The illicit drug using patients showed the largest improvement in cognition, especially among the youngest patients. Younger patients with non-affective psychosis and illicit drug use showed more cognitive improvement the first weeks after acute psychosis as compared to psychosis only. This suggests that the illicit drug users constitute a sub-group with less stable cognitive deficits and less cognitive vulnerability.

Extensive use of illicit drugs is common in patients with non-affective psychosis, typically about 40–50% of patients with psychosis report lifetime substance use disorder (Regier et al., 1990, Kovasznay et al., 1997, Blanchard et al., 2000 and Margolese et al., 2004). The range of reported substance use disorder is large in psychosis, however, from 10% to 70%, depending on methodological differences and population characteristics (Jimenez-Castro et al., 2011). Rates of cannabis use have been found to be especially high; a review reported that median rate for current cannabis use disorder was 28.6% in first-episode and 22.0% for more long-lasting non-affective psychosis (Koskinen et al., 2010). Substance use in psychosis has been associated with more hospitalizations, non-adherence, heightened suicide risk and adverse long-term clinical outcomes compared to patients with psychosis who do not use illicit drugs (Talamo et al., 2006, Zammit et al., 2008, Schmidt et al., 2011, Large et al., 2014, Sara et al., 2014 and Tarricone et al., 2014). Some of the most frequently used illicit drugs, cannabis and stimulants (Ringen et al., 2008, Helseth et al., 2009 and Koskinen et al., 2010), may induce transient positive psychosis symptoms and cognitive alterations (Curran et al., 2004, D’Souza et al., 2005, D’Souza et al., 2009 and Smith et al., 2009). A majority of patients with schizophrenia and non-affective psychoses have clinical significant cognitive deficits (Keefe and Fenton, 2007, Palmer et al., 2009 and Lewandowski et al., 2011), often depicted as a vulnerability factor that is present also before the development of psychosis (Woodberry et al., 2008) and in high-risk populations (Brewer et al., 2005 and Woodberry et al., 2010). It is likely, however, that the use of illicit drugs influences cognition in psychosis. Experimental studies have shown that the most prominent psychoactive substance in cannabis, Delta-9-tetrahydrocannabinol (THC), have an especially strong negative effect on cognition in individuals with psychosis (D’Souza et al., 2005 and Henquet et al., 2006). Most studies, have found better cognitive functioning in psychosis patients with lifetime or previous illicit drug use as compared to psychosis alone (Potvin et al., 2008, Løberg and Hugdahl, 2009, Rabin et al., 2011 and Yucel et al., 2012), although this has not been consistently shown in all studies (e.g. Wobrock et al., 2013). Furthermore, for cannabis, superior cognitive functioning in the illicit drug using group has been reported in first episode psychosis patients (Rodriguez-Sanchez et al., 2010 and Cunha et al., 2013) and at 10-year follow-up after onset of psychosis (Stirling et al., 2005), and replicated by means of functional Magnetic Resonance Imaging (fMRI) (Løberg et al., 2012). Whilst intake of THC has been associated with transient cognitive deficits (D’Souza et al., 2005 and D’Souza et al., 2009), mixed results for the intake of stimulants have been reported with both better (Barch and Carter, 2005 and Bahorik et al., 2013) and worse (Meijer et al., 2012) cognitive performance in non-affective psychosis. It is likely that the effect of both cannabis and stimulants use on cognition in patients with non-affective psychosis is time-related (Løberg and Hugdahl, 2009). Possibly, current illicit drug use, like cannabis, influence cognition more negatively, while previous drug use is a marker of a different pathway to psychosis. The illicit drug using psychotic patients may constitute a sub-group with less cognitive vulnerability (Løberg et al., 2012 and Ferraro et al., 2013); illicit drug use may have a more temporary influence on cognition, generating a short-term cognitive and psychotic breakdown (Løberg and Hugdahl, 2009). Thus, illicit drug use, like cannabis, may create transient deficits in cognition paralleling the period of acute psychosis. To test this hypothesis, it is necessary to examine the change of cognitive functioning from the time of an acute psychotic breakthrough to the stabilization of psychotic symptoms in patients with and without drug use. Furthermore, the drug using group should be abstinent from illicit drugs in the follow-up period to enable possible cognitive improvement. To accomplish this, only patients with symptoms of acute psychosis admitted to a psychiatric in-patient emergency department were included, and the patients were followed while hospitalized to minimize use of illicit drugs. By 4–6 weeks most of the long-term effects of illicit drug use should be minimized, and most psychosis symptoms responding to treatment (Sherwood et al., 2006 and Szoke et al., 2008). Follow-up was therefore set to time of discharge from the acute ward or after 6 weeks at the latest, if not discharged earlier. This was allowed for both a naturalistic prognostic design and a reduction of variability in regard to time to follow-up. Furthermore, a brief neuropsychological screening instrument with alternative forms; the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), was used to minimize potential practice effects (Randolph, 1998, Gold et al., 1999 and Beglinger et al., 2005). Earlier longitudinal studies on cognitive functioning have usually not addressed the issue of practice effects sufficiently (Goldberg et al., 2007 and Goldberg et al., 2010). Practice effects can be particularly evident when there are short time intervals between repeated neuropsychological testing, and the effect seems to be strongest from baseline to the second testing (Hausknecht et al., 2007 and Bartels et al., 2010). Latent Growth Curve modeling was chosen to examine cognitive trajectories from baseline to follow-up in order to minimize the effect of missing data, controlling for the baseline level in cognitive functioning and varying test–retest intervals. The aim of the present study was to compare cognitive changes in non-affective psychosis patients with illicit drug use to cognitive changes in non-affective psychosis patients with no illicit drug use after an acute psychotic episode. It was hypothesized that the drug group would show more improvement in cognitive functioning from time of admission to a psychiatric emergency ward to time of discharge from the acute ward or after 6 weeks at the latest.