Attentional dysfunction in abstinent long-term cannabis users with and without schizophrenia

Abstract

Long-term cannabis use may confer cognitive deficits and increased risk of psychosis. However, the relationship between cannabis use and schizophrenia is complex. In particular, little is known about the effects of chronic cannabis use on the attention-related electric brain response in schizophrenia. We investigated auditory novelty and oddball P300 evoked potentials in a mixed sample of first-episode and chronic schizophrenic patients and healthy controls with (SZCA, n = 20; COCA, n = 20, abstinence ≥28 days) or without (SZ, n = 20; CO, n = 20) chronic cannabis use. Duration of regular cannabis use was 8.3 ± 5.6 (SZCA) and 9.1 ± 7.1 (COCA) years. In general, schizophrenic patients showed reduced P300 amplitudes. Cannabis use was associated with both a reduced early and late left-hemispheric novelty P300. There was a significant 'diagnosis × cannabis' interaction for the left-hemispheric late novelty P300 in that cannabis use was associated with a reduced amplitude in the otherwise healthy but not in the schizophrenic group compared with their relative control groups (corrected p < 0.02; p > 0.9, respectively). The left-hemispheric late novelty P300 in the otherwise healthy cannabis group correlated inversely with amount and duration of cannabis use (r = -0.50, p = 0.024; r = -0.57, p = 0.009, respectively). Our study confirms attentional deficits with chronic cannabis use. However, cannabis use may lead to different cognitive sequelae in patients with schizophrenia and in healthy controls, possibly reflecting preexisting alterations in the endocannabinoid system in schizophrenia.

Are cannabis-using and non-using patients different groups? Towards understanding the neurobiology of cannabis use in psychotic disorders

“…A number of distinct electrophysiological alterations have also been noted in P-C versus P-NC indicating pre-attentional, attentional and reward cue deficits. Although one study demonstrated no differences between cannabis-using and non-using patients, in P50 sensory gating (Rentzsch et al, 2007), differences have been demonstrated in prepulse inhibition (PPI) with relative sparing of the diminished PPI amplitude seen in P-NC; (Morales-Muñoz et al, 2015; Scholes-Balog and Martin-Iverson, 2011); reduced P300 amplitudes for P-C versus P-NC to novelty and oddball auditory stimuli (Rentzsch et al, 2016), modulation of mismatch negativity (MMN) (Pesa et al, 2012; Rentzsch et al, 2011) and altered late positive potential to reward cues such that there appears to be blunting of response to natural but not cannabis visual cues in the P-C group (Cassidy et al, 2014). MMN is believed to index glutamatergic function and is discussed further below (see III(iii)).…”

Cannabinoids and Vanilloids in Schizophrenia: Neurophysiological Evidence and Directions for Basic Research

“…THC administration in healthy subjects weakens the P300 response recorded from midline frontal, central, and parietal electrodes during a choice reaction task, indicating the involvement of the eCB system in attention and working memory (Roser et al, 2008). Weak P300 has also been shown in chronic cannabis users (Rentzsch et al, 2016) which however manifest increased P300 amplitude when exposed to unpleasant trait words, and decreased negative symptoms such as affective blunting (Skosnik et al, 2008). These findings suggest that the eCB system may be particularly relevant for the positive symptoms of schizophrenia.…”

Esrar Kullanımının Yol Açtığı Tedaviye Dirençli Bir Psikotik Bozukluk Olgusu (Olgu Sunumu)

“…Murray ve arkadaşları (2017) da yapmış oldukları çalışmada, esrar kullanımının psikotik belirtiler ve şizofreni benzeri psikoz riskinin artışı ile ilişkili olduğunu saptamışlardır (4). Uzun süren esrar kullanımının sağlıklı bireylerde dahi nörobilişsel yapıda bozulmalara sebep olduğu ve psikoz riskini arttırdığı kanıtlanmıştır (7). Bu oturumların uygulandığı süreçte bireyin maddeyi mantığa uygunlaştırma çabası, anne baba tutumunun aşırı izin verici olması, paranoid düşünce eğilimi, konsantrasyonda azalma ve sorumluluk almama gibi özelliklerinden dolayı danışana "bireysel baş etmede yetersizlik" hemşirelik tanısı konmuştur.…”

“…Murray ve arkadaşları (2017) da yapmış oldukları çalışmada, esrar kullanımının psikotik belirtiler ve şizofreni benzeri psikoz riskinin artışı ile ilişkili olduğunu saptamışlardır (4). Uzun süren esrar kullanımının sağlıklı bireylerde dahi nörobilişsel yapıda bozulmalara sebep olduğu ve psikoz riskini arttırdığı kanıtlanmıştır (7).…”