Anticholinergic Burden and Cognitive Performance in Patients With Schizophrenia: A Systematic Literature Review

Anticholinergic load: A commonly neglected and preventable risk to cognition during schizophrenia treatment?

Background

Cognitive impairment is a widespread feature of schizophrenia, affecting nearly 80 % of patients. Prior research has linked the anticholinergic burden of psychiatric medications to these cognitive deficits. However, the impact of the anticholinergic burden from medications for physical morbidity remains underexplored. This study aimed to evaluate the anticholinergic burden of psychiatric and physical medications in patients with schizophrenia and assess its impact on cognitive function.

Methods

A total of 178 patients with schizophrenia were recruited. The assessments included an ad hoc questionnaire for collecting demographic and clinical data. Anticholinergic burden was evaluated using the cumulative Drug Burden Index (cDBI) for each participant, and cognitive function was assessed using MATRICS. Psychopathology was measured using the PANSS, CDSS, CAINS, and the CGI-S. Statistical analysis included Student's t-tests, ANOVA, Pearson correlations, and multiple linear regressions.

Results

The average cDBI was 1.3 (SD = 0.9). The model developed explained 40.80 % of the variance. The variable with the greatest weight was the cDBI (B = -11.148, p = 0.010). Negative-expression (B = -2.740, p = 0.011) and negative-experiential (B = -1.175, p = 0.030) symptoms were also associated with lower global cognitive score. However, more years of education (B = 5.140, p < 0.001) and cigarettes per day (B = 1.331, p < 0.001) predicted a better global cognitive score.

Conclusion

This study identified specific predictors of global cognition in schizophrenia, with anticholinergic burden emerging as the strongest factor. Our findings underscore the importance of considering the anticholinergic burden of treatments, in addition to negative symptoms, when designing interventions to optimize or maintain cognitive function in patients with schizophrenia.

Psychosis as a disorder of muscarinic signalling: psychopathology and pharmacology

Dopaminergic receptor antagonism is a crucial component of all licensed treatments for psychosis, and dopamine dysfunction has been central to pathophysiological models of psychotic symptoms. Some clinical trials, however, indicate that drugs that act through muscarinic receptor agonism can also be effective in treating psychosis, potentially implicating muscarinic abnormalities in the pathophysiology of psychosis. Here, we discuss understanding of the central muscarinic system, and we examine preclinical, behavioural, post-mortem, and neuroimaging evidence for its involvement in psychosis. We then consider how altered muscarinic signalling could contribute to the genesis and maintenance of psychotic symptoms, and we review the clinical evidence for muscarinic agents as treatments. Finally, we discuss future research that could clarify the relationship between the muscarinic system and psychotic symptoms.

Comparative analysis of anticholinergic burden scales to explain iatrogenic cognitive impairment in schizophrenia: results from the multicenter FACE-SZ cohort

Aim

The anticholinergic properties of medications are associated with poorer cognitive performance in schizophrenia. Numerous scales have been developed to assess anticholinergic burden and yet, there is no consensus indicating which anticholinergic burden scale is more relevant for patients with schizophrenia. We aimed to identify valid scales for estimating the risk of iatrogenic cognitive impairment in schizophrenia.

Methods

We identified 27 scales in a literature review. The responses to neuropsychological tests of 839 individuals with schizophrenia or schizoaffective disorder in the FACE-SZ database were collected between 2010 and 2021. We estimated the association between objective global cognitive performance and the 27 scales, the number of psychotropic drugs, and chlorpromazine and lorazepam equivalents in bivariable regressions in a cross-sectional design. We then adjusted the bivariable models with covariates: the predictors significantly associated with cognitive performance in multiple linear regressions were considered to have good concurrent validity to assess cognitive performance.

Results

Eight scales, the number of psychotropic drugs, and drug equivalents were significantly associated with cognitive impairment. The number of psychotropic drugs, the most convenient predictor to compute, was associated with worse executive function (Standardized β = -0.12, p = .004) and reasoning (Standardized β = -0.08, p = .037).

Conclusion

Anticholinergic burden, the number of psychotropic drugs, and drug equivalents were weakly associated with cognition, thus suggesting that cognitive impairment in schizophrenia and schizoaffective disorder is explained by factors other than medication. The number of psychotropic drugs was the most parsimonious method to assess the risk of iatrogenic cognitive impairment.

Modeling the effects of treatment resistance and anticholinergic burden on cognitive function domains in patients with schizophrenia

The contribution of anticholinergic burden to cognitive function in patients with treatment resistant schizophrenia (TRS) is uncertain. This case-control study aims to comprehensively examine the association between treatment resistance and cognitive functions and the contribution of anticholinergic burden in patients with schizophrenia. Anticholinergic burden of all patients was calculated using the Anticholinergic Cognitive Burden scale. Exploratory Factor Analysis of 11 cognitive assessments identified four cognitive domains: verbal memory, attention and general cognitive functions, visual memory and processing speed, and executive function. Two structural equation models (SEM) examined the relationship of TRS and these cognitive functions with, and without considering anticholinergic burden. A total of 288 participants were included (TRS N=111, non-TRS N=177). Patients with TRS performed poorer than the non-TRS group only in the executive function domain. Anticholinergic burden contributed significantly to the attention and general cognitive functions, visual memory and processing speed, and executive function. The impact of TRS on executive function was no longer significant after adding anticholinergic burden to the SEM. Results suggested that anticholinergic burden contributes to a wide range of cognitive function impairment in patients with schizophrenia and is likely to be part of the apparent differences of cognitive function between TRS and non-TRS.

An Evidence-Based Update on Anticholinergic Use for Drug-Induced Movement Disorders

Drug-induced movement disorders (DIMDs) are associated with use of dopamine receptor blocking agents (DRBAs), including antipsychotics. The most common forms are drug-induced parkinsonism (DIP), dystonia, akathisia, and tardive dyskinesia (TD). Although rare, neuroleptic malignant syndrome (NMS) is a potentially life-threatening consequence of DRBA exposure. Recommendations for anticholinergic use in patients with DIMDs were developed on the basis of a roundtable discussion with healthcare professionals with extensive expertise in DIMD management, along with a comprehensive literature review. The roundtable agreed that "extrapyramidal symptoms" is a non-specific term that encompasses a range of abnormal movements. As such, it contributes to a misconception that all DIMDs can be treated in the same way, potentially leading to the misuse and overprescribing of anticholinergics. DIMDs are neurobiologically and clinically distinct, with different treatment paradigms and varying levels of evidence for anticholinergic use. Whereas evidence indicates anticholinergics can be effective for DIP and dystonia, they are not recommended for TD, akathisia, or NMS; nor are they supported for preventing DIMDs except in individuals at high risk for acute dystonia. Anticholinergics may induce serious peripheral adverse effects (e.g., urinary retention) and central effects (e.g., impaired cognition), all of which can be highly concerning especially in older adults. Appropriate use of anticholinergics therefore requires careful consideration of the evidence for efficacy (e.g., supportive for DIP but not TD) and the risks for serious adverse events. If used, anticholinergic medications should be prescribed at the lowest effective dose and for limited periods of time. When discontinued, they should be tapered gradually.

Comparative analysis of anticholinergic burden scales to explain iatrogenic cognitive impairment and self-reported side effects in the euthymic phase of bipolar disorders: Results from the FACE-BD cohort

Bipolar disorders (BD) are characterized by cognitive impairment during the euthymic phase, to which treatments can contribute. The anticholinergic properties of medications, i.e., the ability of a treatment to inhibit cholinergic receptors, are associated with cognitive impairment in elderly patients and people with schizophrenia but this association has not been well characterized in individuals with remitted BD. Moreover, the validity of only one anticholinergic burden scale designed to assess the anticholinergic load of medications has been tested in BD. In a literature review, we identified 31 existing scales. We first measured the associations between 27 out of the 31 scales and objective cognitive impairment in bivariable regressions. We then adjusted the bivariable models with covariates: the scales significantly associated with cognitive impairment in bivariable and multiple logistic regressions were defined as having good concurrent validity to assess cognitive impairment. In a sample of 2,031 individuals with euthymic BD evaluated with a neuropsychological battery, two scales had good concurrent validity to assess cognitive impairment, whereas chlorpromazine equivalents, lorazepam equivalents, the number of antipsychotics, or the number of treatments had not. Finally, similar analyses with subjective anticholinergic side-effects as outcome variables reported 14 scales with good concurrent validity to assess self-reported peripheral anticholinergic side-effects and 13 to assess self-reported central anticholinergic side-effects. Thus, we identified valid scales to monitor the anticholinergic burden in BD, which may be useful in estimating iatrogenic cognitive impairment in studies investigating cognition in BD.

Effect of anticholinergic burden on brain activity during Working Memory and real-world functioning in patients with schizophrenia

Cognitive impairment has been associated with poor real-world functioning in patients with Schizophrenia. Previous studies have shown that pharmacological treatment with anticholinergic properties may contribute to cognitive impairment in Schizophrenia. We investigated the effect of the anticholinergic burden (ACB) on brain activity, cognition, and real-world functioning in Schizophrenia. We hypothesized that greater ACB would be associated with altered brain activity along with poorer cognitive performance and lower real-world functioning. A sample of 100 patients with a diagnosis of schizophrenia or schizoaffective disorder was recruited in the naturalistic multicenter study of the Italian Network for Research on Psychoses (NIRP) across 7 centres. For each participant, ACB was evaluated using the Anticholinergic Cognitive Burden scale. The association of ACB with brain function was assessed using BOLD fMRI during the N-Back Working Memory (WM) task in a nested cohort (N = 31). Real-world functioning was assessed using the Specific Level of Functioning (SLOF) scale. Patients with high ACB scores (≥3) showed lower brain activity in the WM frontoparietal network (TFCE corrected alpha <0.05) and poorer cognitive performance (p = 0.05) than patients with low ACB scores (<3). Both effects were unaffected by demographic characteristics, clinical severity, and antipsychotic dosage. Moreover, patients with high ACB showed poorer real-world functioning than patients with lower ACB (p = 0.03). Our results suggest that ACB in Schizophrenia is associated with impaired WM and abnormal underlying brain function along with reduced real-world functioning. Clinical practice should consider the potential adverse cognitive effects of ACB in the treatment decision-making process.

Cognitive impairment in schizophrenia: aetiology, pathophysiology, and treatment

Cognitive deficits are a core feature of schizophrenia, account for much of the impaired functioning associated with the disorder and are not responsive to existing treatments. In this review, we first describe the clinical presentation and natural history of these deficits. We then consider aetiological factors, highlighting how a range of similar genetic and environmental factors are associated with both cognitive function and schizophrenia. We then review the pathophysiological mechanisms thought to underlie cognitive symptoms, including the role of dopamine, cholinergic signalling and the balance between GABAergic interneurons and glutamatergic pyramidal cells. Finally, we review the clinical management of cognitive impairments and candidate novel treatments.

Effects of antipsychotic and anticholinergic medications on cognition in chronic patients with schizophrenia

BACKGROUND

Patients with psychosis frequently use a variety of psychotropic medicines, many of which have anticholinergic effects that can impair cognition. Therefore, this study aimed to evaluate whether there is an association between medications used for neuropsychological disorders/symptoms and cognition in patients with schizophrenia, focusing on their anticholinergic load and antipsychotic doses.

STUDY DESIGN

A cross-sectional study between July 2019 and Mars 2020 at the Psychiatric Hospital of the Cross-Lebanon enrolled 120 inpatients diagnosed with schizophrenia. The total anticholinergic burden was calculated based on the Anticholinergic Drug Scale (ADS), and the chlorpromazine equivalent dose was calculated using the Andreasen method to assess the relative antipsychotic dose. Also, the objective cognition was assessed using the Brief Assessment of Cognition in Schizophrenia (BACS) tool.

STUDY RESULTS

A significantly higher BACS total score (r = -0.33, p < 0.001), higher verbal memory (r = -0.26, p = 0.004), higher working memory (r = -0.20, p = 0.03), higher motor speed (r = -0.36, p < 0.001), and higher attention and speed of information processing (r = -0.27, p = 0.003) were significantly associated with lower chlorpromazine equivalent dose. Higher ADS (Standardized Beta (SB) = -.22; p = .028), higher chlorpromazine equivalent dose (SB = -.30; p = .001), and taking mood stabilizer medications (SB = -.24; p = .004) were significantly associated with lower cognition.

CONCLUSION

This study confirms that the cognitive functions of chronic patients with schizophrenia may be affected by medications and their anticholinergic burden. More studies are needed to explain the role of cholinergic neurotransmission and general neurochemical mechanisms in the cognitive impairment of patients with schizophrenia.

Prescribing Trends for the Same Patients with Schizophrenia Over 20 Years

Background

Recent pharmacoepidemiology data show an increase in the proportion of patients receiving second-generation antipsychotic (SGA) monotherapy, but no studies have analyzed the same patients over a long period of time. Therefore, in this study, we retrospectively evaluated schizophrenia patients with available data for 20 years to determine whether the drug treatments in the same patients have changed in the past 20 years.

Methods

The study began in April 2021 and was conducted in 15 psychiatric hospitals in Japan. Schizophrenia patients treated in the same hospital for 20 years were retrospectively examined for all prescriptions in 2016, 2011, 2006, and 2001 (ie, every 5 years).

Results

The mean age of the 716 patients surveyed in 2021 was 61.7 years, with 49.0% being female. The rate of antipsychotic monotherapy use showed a slight increasing trend over the past 20 years; the rate of SGA use showed a marked increasing trend from 28.9% to 70.3% over the past 20 years, while the rate of SGA monotherapy use showed a gradual increasing trend over the past 20 years. The rates of concomitant use of anticholinergics, antidepressants, anxiolytics/sleep medications, and mood stabilizers showed decreasing, flat, flat, and flat trends over the past 20 years, respectively.

Conclusion

The results of this study showed a slow but steady substitution of SGAs for first-generation antipsychotics (FGAs) over time, even in the same patients.

Relapse of first-episode schizophrenia patients and neurocognitive impairment: The role of dopaminergic and anticholinergic burden

BACKGROUND

The prevention of relapse may be a key factor to diminish the cognitive impairment of first-episode schizophrenia (FES) patients. We aimed to ascertain the effects of relapse, and dopaminergic and anticholinergic treatment burdens on cognitive functioning in the follow-up.

METHODS

Ninety-nine FES patients participated in this study. Cognitive assessments were performed at baseline and after 3 years of follow-up or, in those patients who relapsed, after &gt;2 months of stabilization of the new acute psychotic episode. The primary outcomes were final cognitive dimensions.

RESULTS

Repeated measures MANOVA analyses showed improvements in the whole sample on the end-point assessments in processing speed and social cognition. However, only impairment in social cognition showed a significant interaction with relapse by time in this sample. Relapse in FES patients was significantly associated with poor performance on end-point assessments of working memory, social cognition and global cognitive score. Anticholinergic burden, but not dopaminergic burden, was associated with verbal memory impairment. These significant associations resulted after controlling for baseline cognitive functioning, relapse and dopaminergic burden.

CONCLUSIONS

The relationship between relapse and cognitive impairment in recovered FES patients seems to be particularly complex at the short-term follow-up of these patients. While relapse was associated with working memory, social cognition impairments and global cognitive score, anticholinergic burden might play an additional worsening effect on verbal memory. Thus, tailoring or changing antipsychotics and other drugs to reduce their anticholinergic burden may be a potential modifiable factor to diminish cognitive impairment at this stage of the illness.

Adverse Drug Reactions in Relation to Clozapine Plasma Levels: A Systematic Review

Clozapine is the gold standard for treatment-resistant schizophrenia. Serious and even life-threatening adverse effects, mostly granulocytopenia, myocarditis, and constipation, are of great clinical concern and constitute a barrier to prescribing clozapine, thus depriving many eligible patients of a lifesaving treatment option. Interestingly, clozapine presents variable pharmacokinetics affected by numerous parameters, leading to significant inter- and intra-individual variation. Therefore, therapeutic drug monitoring of plasma clozapine levels confers a significant benefit in everyday clinical practice by increasing the confidence of the prescribing doctor to the drug and the adherence of the patient to the treatment, mainly by ensuring effective treatment and limited dose-related side effects. In the present systematic review, we aimed at identifying how a full range of adverse effects relates to plasma clozapine levels, using the Jadad grading system for assessing the quality of the available clinical evidence. Our findings indicate that EEG slowing, obsessive-compulsive symptoms, heart rate variability, hyperinsulinemia, metabolic syndrome, and constipation correlate to plasma clozapine levels, whereas QTc, myocarditis, sudden death, leucopenia, neutropenia, sialorrhea, are rather unrelated. Rapid dose escalation at the initiation of treatment might contribute to the emergence of myocarditis, or leucopenia. Strategies for managing adverse effects are different in these conditions and are discussed accordingly.

Clinical Utility of Medication-Based Risk Scores to Reduce Polypharmacy and Potentially Avoidable Healthcare Utilization

The management of multiple chronic health conditions often requires patients to be exposed to polypharmacy to improve their health and enhance their quality of life. However, exposure to polypharmacy has been associated with an increased risk for adverse effects, drug-drug interactions, inappropriate prescribing, medication nonadherence, increased healthcare utilization such as emergency department visits and hospitalizations, and costs. Medication-based risk scores have been utilized to identify patients who may benefit from deprescribing interventions and reduce rates of inappropriate prescribing. These risk scores may also be utilized to prompt targeted discussions between patients and providers regarding medications or medication classes contributing to an individual’s risk for harm, eventually leading to the deprescribing of the offending medication(s). This opinion will describe existing medication-based risk scores in the literature, their utility in identifying patients at risk for specific adverse events, and how they may be incorporated in healthcare settings to reduce rates of potentially inappropriate polypharmacy and avoidable healthcare utilization and costs.

The Interplay between Vitamin D, Exposure of Anticholinergic Antipsychotics and Cognition in Schizophrenia

Vitamin D deficiency is a frequent finding in schizophrenia and may contribute to neurocognitive dysfunction, a core element of the disease. However, there is limited knowledge about the neuropsychological profile of vitamin D deficiency-related cognitive deficits and their underlying molecular mechanisms. As an inductor of cytochrome P450 3A4, a lack of vitamin D might aggravate cognitive deficits by increased exposure to anticholinergic antipsychotics. This cross-sectional study aims to assess the relationship between 25-OH-vitamin D-serum concentrations, anticholinergic drug exposure and neurocognitive functioning (Brief Assessment of Cognition in Schizophrenia, BACS, and Trail Making Test, TMT) in 141 patients with schizophrenia. The anticholinergic drug exposure was estimated by adjusting the concentration of each drug for its individual muscarinic receptor affinity. Using regression analysis, we observed a positive relationship between vitamin D levels and processing speed (TMT-A and BACS Symbol Coding) as well as executive functioning (TMT-B and BACS Tower of London). Moreover, a negative impact of vitamin D on anticholinergic drug exposure emerged, but the latter did not significantly affect cognition. When other cognitive items were included as regressors, the impact of vitamin D remained only significant for the TMT-A. Among the different cognitive impairments in schizophrenia, vitamin D deficiency may most directly affect processing speed, which in turn may aggravate deficits in executive functioning. This finding is not explained by a cytochrome P450-mediated increased exposure to anticholinergic antipsychotics.