Effects of Tobacco Smoking Status on Verbal Learning and Memory in Patients With Schizophrenia and Non-Psychiatric Controls

Verbal and visual learning ability in patients with treatment-resistant schizophrenia: A 1-year follow-up study

Objective

In the general population, repeated cognitive testing produces learning effects with potential for improved test performance. It is currently unclear whether the same effect of repeated cognitive testing on cognition pertains to people living with schizophrenia, a condition often associated with significant cognitive impairments. This study aims to evaluate learning ability in people with schizophrenia and-considering the evidence that antipsychotic medication can additionally impair cognitive performance-explore the potential impact of anticholinergic burden on verbal and visual learning.

Method

The study included 86 patients with schizophrenia, treated with clozapine, who had persisting negative symptoms. They were assessed at baseline, weeks 8, 24 and 52 using Positive and Negative Syndrome Scale, Hopkins Verbal Learning Test-Revised (HVLT-R) and Brief Visuospatial Memory Test-R (BVMT-R).

Results

There were no significant improvements in verbal or visual learning across all measurements. Neither the clozapine/norclozapine ratio nor anticholinergic cognitive burden significantly predicted participants' total learning. Premorbid IQ was significantly associated with verbal learning on the HVLT-R.

Conclusions

These findings advance our understanding of cognitive performance in people with schizophrenia and demonstrate limited learning performance in individuals with treatment-refractory schizophrenia.

Dose-dependent effects of Varenicline on tobacco craving and withdrawal in tobacco smokers with and without schizophrenia

BACKGROUND

People with schizophrenia (SCZ) have significantly higher tobacco smoking rates and lower quit rates than the general population. Varenicline, a partial agonist at α4β2 nicotinic acetylcholine receptors (nAChRs) is an effective smoking cessation pharmacotherapy, however, investigation into its effects in SCZ are less well-studied and mechanisms may differ from non-psychiatric controls due to dysregulation in nAChR neurotransmission associated with SCZ. Here, we investigate whether Varenicline attenuates acute abstinence-induced increases in craving and withdrawal in participants with and without SCZ.

METHODS

Following biochemically-verified overnight abstinence and subsequent smoking reinstatement, individuals with nicotine-dependence (n = 13 SCZ or schizoaffective; n = 12 controls) were assessed on the Minnesota Nicotine Withdrawal Scale (MNWS) and Tiffany Questionnaire for Smoking Urges (TQSU). Participants were pretreated in a double-blind, counterbalanced manner with Varenicline (0, 1 or 2 mg/day x 3 days) over three separate weeks. Data were analyzed using linear mixed-effects modelling and estimated marginal means.

RESULTS

Robust effects of smoking abstinence were observed on TQSU and MNWS scores in SCZ and control participants. Relative to 1 mg, 2 mg/day of Varenicline attenuated abstinence-induced increases in craving (TQSU Factor 1 d=-0.47, p = .006; TQSU Factor 2 d=-0.42, p = .008) and withdrawal (MNWS d=-0.35, p = .03) in both groups.

CONCLUSION

Our preliminary findings suggest that subacute Varenicline treatment reduces abstinence-induced craving and withdrawal in participants with and without SCZ. The efficacy of Varenicline on tobacco withdrawal and craving requires further study.

Sex Differences in Obesity and Cognitive Function in Chinese Elderly Patients With Chronic Schizophrenia

BACKGROUND

It is well known that schizophrenia is associated with sex differences. However, no study has explored the sex differences in obesity and cognitive function in elderly Chinese patients with schizophrenia.

OBJECTIVE

This study aimed to compare sex differences in obesity and cognitive function in elderly Chinese individuals with schizophrenia.

METHODS

A total of 304 elderly patients with schizophrenia and 130 sex- and age-matched healthy controls from the community were recruited. Demographic, clinical, and lipid parameters were collected for all subjects. The Montreal Cognitive Assessment (MoCA) was used to assess the global cognitive functions of the participants, while the Positive and Negative Syndrome Scale (PANSS) was used to assess psychopathological symptoms in patients with schizophrenia.

RESULTS

Of the patients with schizophrenia, the prevalence of obesity in men and women was 11.7% (19/163) and 21.3% (30/141), respectively. The score (14.51 ± 6.504) of MOCA in elderly male patients with schizophrenia was significantly higher than that (11.40 ± 6.822) in female patients. There was a positive correlation between the MOCA scores and body mass index (BMI) (r=0.206, p=0.018) in male elderly patients with schizophrenia. Conversely, the MOCA scores of female elderly patients with schizophrenia did not correlate with BMI (p>0.05). However, we found no sex differences in obesity and cognition among control older adults.

CONCLUSIONS

Our findings suggest that there are significant sex differences in obesity and cognitive function in elderly Chinese patients with schizophrenia.

Neuromodulation to Treat Substance Use Disorders in People With Schizophrenia and Other Psychoses: A Systematic Review

BACKGROUND

Substance use disorders (SUDs) are a common yet poorly studied comorbidity in individuals with psychotic disorders. The co-occurrence of the two complicates recovery and interferes with pharmacological and behavioral treatment response and adherence. Recently, researchers have been exploring both invasive and non-invasive neuromodulation techniques as potential treatment methods for SUDs. We review the evidence that neuromodulation may reduce substance craving and consumption in individuals with schizophrenia.

METHODS

A comprehensive literature search of PubMed, MEDLINE, and PsycINFO databases was conducted (N = 1,432). Of these, we identified seven studies examining the effects of repetitive transcranial magnetic stimulation (rTMS) and two studies using transcranial direct current stimulation (tDCS) on drug consumption and craving in schizophrenia or schizoaffective disorders.

RESULTS

Despite the limited number of studies in this area, the evidence suggests that rTMS to the dorsolateral prefrontal cortex (DLPFC) may reduce cannabis and tobacco use in patients with schizophrenia and schizoaffective disorder. Findings with tDCS, however, were inconclusive.

DISCUSSION

Our systematic review suggests that rTMS applied to DLPFC is a safe and promising therapeutic technique for the management of comorbid schizophrenia and SUDs, with the majority of the evidence in tobacco use disorder. However, there was substantial heterogeneity in study methods, underscoring the need to optimize stimulation parameters (e.g., frequency, duration, and target regions). Larger clinical trials are needed to establish the efficacy of rTMS in reducing drug consumption and craving in psychotic patients, ideally in comparison to existing pharmacological and behavioral interventions.