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Post-intervention effectiveness of a computerized personalized cognitive stimulation program adapted according to cognitive reserve in older adults without cognitive impairment in Primary Care: A randomized clinical trial.

BACKGROUND: Cognitive reserve may influence responsiveness to cognitive interventions, yet it is rarely used to tailor computerized stimulation. OBJECTIVE: To evaluate the effectiveness of a computerized cognitive stimulation program personalized according to cognitive reserve on cognition, reserve-related activities, and digital competence in community-dwelling older adults without cognitive impairment in Primary Care. METHODS: In this randomized clinical trial, 102 adults aged ≥65 years with normal cognitive performance were recruited from three primary care centers in Zaragoza, Spain, and stratified by cognitive reserve level before random allocation to intervention or control. The intervention comprised digital literacy sessions followed by 8 weeks of home-based computerized cognitive stimulation tailored to participants' cognitive reserve profiles and life history. Controls received a single group-based health education session focused on maintaining everyday cognitive activity. Outcomes were assessed at baseline and post-intervention using global cognition (MEC-35), the Cognitive Reserve Questionnaire, the Mobile Device Proficiency Questionnaire-16, and domain-specific neuropsychological tests. A total of 100 participants completed the final evaluation and were included in complete-case analyses. RESULTS: Compared with controls, the intervention group showed greater adjusted post-intervention improvements in global cognition (MEC-35 between-group difference: 1.8 points) and several cognitive measures, including temporal orientation, calculation, attention, praxis, verbal fluency, processing speed, executive functions, and verbal learning. CRQ scores and digital competence also improved, with small-to-large effect sizes. CONCLUSIONS: A computerized cognitive stimulation program adapted according to cognitive reserve appears feasible in Primary Care and may improve cognition, engagement in reserve-related activities, and digital competence in older adults without cognitive impairment.

Humans

Protective Effects of Genetic Proxies of Cognitive Reserve in Parkinson's Disease: A Longitudinal Multi-Cohort Study.

BACKGROUND: Resilience factors are crucial in the progression of neurodegenerative diseases. However, it remains unclear whether a genetic predisposition to cognitive reserve influences clinical heterogeneity in the prognosis of Parkinson's disease (PD). OBJECTIVES: The aim is to evaluate the utility of polygenic scores (PGSs) for cognitive reserve proxies, including intelligence (INT), educational attainment (EA), and occupational attainment (OA), in predicting the clinical progression of PD. METHODS: Genetic and clinical data for progression of PD (progression to Hoehn and Yahr stage &#x2265;3, progression to a Montreal Cognitive Assessment score&#x2009;&#x2264;24, and occurrence of psychosis) were obtained from the Accelerating Medicine Partnership Parkinson's Disease database. We conducted multivariate Cox regression analysis, adjusting for relevant covariates, including years of education, variants in APOE, GBA1, LRRK2, and other cognitive reserve-related PGSs. RESULTS: All cognitive reserve-related PGSs significantly reduced the risk of cognitive decline, and EA-PGS (hazard ratio [HR], 0.550; 95% confidence interval [CI], 0.447-0.676; P&#x2009;<&#x2009;0.001) remained significant after controlling for INT-PGS and OA-PGS. EA-PGS (HR, 0.805; 95% CI, 0.672-0.964; P&#x2009;=&#x2009;0.019) was significantly associated with better motor prognosis after controlling for other PGSs. OA-PGS was linked to a decreased risk of developing psychosis in PD and remained significant after adjusting for others (HR, 0.784; 95% CI, 0.631-0.975; P&#x2009;=&#x2009;0.029). CONCLUSIONS: Genetic proxies of cognitive reserve are associated with a reduced risk of cognitive decline, motor progression, and development of psychosis in PD. These findings may enhance our understanding of individual differences in resilience in progression of PD. &#xa9; 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Humans

Role of Polygenic Risk Scores in Predicting Cognitive Functioning after Mild Traumatic Brain Injury: A TRACK-TBI Study.

Patients with traumatic brain injury (TBI) and Glasgow Coma Scale scores of 13-15 (historically called mild TBI [mTBI]) commonly experience changes in cognitive functioning, including processing speed, memory, and executive functioning. In a prospective sample (N = 523) of individuals of European descent who had been treated in a U.S. level 1 trauma center for mTBI, we examined the prognostic value of four polygenic risk scores (PRS) for cognitive outcomes at 6-months postinjury. To estimate the impact of mTBI on cognition, primary cognitive outcomes were scaled as z-scores reflecting changes in performance relative to predicted preinjury performance. The PRS examined were previously developed and validated to predict cognition-related outcomes of educational attainment (Education-PRS), intelligence (Intelligence-PRS), and Alzheimer's disease (AD-mild traumatic brain injury (APOE)-PRS and AD + APOE-PRS). Both the Education-PRS and Intelligence-PRS displayed bivariate associations with all four cognitive outcomes (&#x3b2; = 0.19-0.32), whereas neither Alzheimer's disease PRS was significantly associated with any outcome. After controlling for other factors known to predict cognitive outcomes of TBI (e.g., sex, education, mTBI severity defined by a combination of Glasgow Coma Scale scores and the presence/absence of acute intracranial findings on clinical neuroimaging), the Education-PRS and Intelligence-PRS remained independently predictive of verbal episodic memory (&#x3b2; = 0.10-0.16), whereas their associations with processing speed and executive functioning were mostly nonsignificant and were mediated through educational attainment. Looking across primary z-score and secondary raw score outcomes, cognitive outcomes 6 months post-mTBI were good on average, and PRS made small independent contributions to outcome prediction. The mediation model findings may support theories of cognitive reserve, which propose that individuals with stronger preinjury cognitive processing abilities (often estimated by educational history) can better compensate for TBI. Moreover, findings indicate that PRS may contribute modestly to multivariable models predicting cognitive function after TBI.

Humans

Premorbid functioning trajectories and the one-year course of cognitive performance in first-episode psychosis: a cluster analysis in PSYSCAN.

BACKGROUND: We examined the course of cognitive performance in first-episode psychosis (FEP) compared to healthy controls (HC), and whether this varied across subgroups of patients defined by premorbid functioning (PMF) trajectories, using a clustering approach. METHODS: Data were collected in 302 FEP and 136 HC subjects participating in PSYSCAN (HEALTH.2013.2.2.1-2-FEP). K-means clustering (Euclidean distance) was used to cluster longitudinal trajectories of different PMF domains simultaneously. Since PMF was assessed retrospectively using the Premorbid Adjustment Scale (PAS), findings should be interpreted with caution, although PAS ratings have shown reasonable validity against prospective data. RESULTS: As expected, FEP showed impaired performance across all cognitive domains compared to HC. We identified four trajectories of PMF: a normal premorbid developmental trajectory (globally-normal, 21&#xa0;%), stable intermediate PMF across domains (stable-intermediate, 29&#xa0;%), stable poor or deteriorating PMF in the academic domain (normal-social/poor-academic, 29&#xa0;%), and a globally impaired group with poor/deteriorating PMF across domains (globally-poor, 21&#xa0;%). These clusters showed distinct levels of post-onset impairments in sustained visual attention, visual working memory and emotion recognition. CONCLUSIONS: This study confirms a positive association between PMF and cognitive performance in the early years following psychosis onset. It aligns with findings that individuals later diagnosed with schizophrenia already show developmental deficits/lags from childhood to early adolescence compared to normally developing children. As PMF can be considered a proxy for cognitive reserve, our results suggest that higher reserve acts as a buffer against cognitive decline and supports better performance on sustained visual attention, complex visual working memory, and aspects of emotion recognition.

Clustering

Heterogeneity Analysis of Associations Involving the Large-Scale Online MindCrowd Survey Memory Test.

INTRODUCTION: Alzheimer's disease and related disorders (ADRDs), as well as general age-related cognitive decline, are known to be multifactorial with heterogeneous etiologies. Identifying and accommodating heterogeneity in any one ADRD-related data set can be pursued using different analytical techniques, each with different assumptions or purposes. For example, whereas a great deal of research has explored clustering individuals or variables that exhibit greater similarity in some way, little research has explored evidence for heterogeneity in the relationships between relevant outcomes, such as performance on a memory test, and risk factors such as environmental exposures, behaviors, or genetic factors among individuals. METHODS: We explored evidence of heterogeneity in the relationships between ability on a memory test, specifically the paired associate learning (PAL) test, and multiple social and demographic risk factors using the large MindCrowd study database (n > 90,000 individuals). We focused on mixtures of regression models but compared models assuming many interaction effects among independent variables as well as random effects. RESULTS: We ultimately find substantial evidence for heterogeneity and offer an intuitive explanation for it involving individual motivation for participating in the MindCrowd study. Basically, we argue that our mixture of regression model analysis results suggest that a smaller group of individuals (&#x223c;16%) likely participated in the MindCrowd study out of a concern for their cognitive abilities as they exhibit stronger and statistically significant negative associations between age, number of medications they are on, some ancestries, and the number correct on the PAL test. They also exhibit stronger positive associations between education and PAL test results in a dose-dependent manner suggesting that a "cognitive reserve" associated with greater education could benefit them. Analysis models assuming interaction terms and random effects suggested that other forms of heterogeneity in the relationships between variables exist in the data set, but their results do not carry with them the same intuitive explanation that the results of the mixture model analyses do. CONCLUSION: We find evidence for heterogeneity in the relationships between social and demographic variables and PAL test results in the large MindCrowd study database. This heterogeneity is likely due to individuals with and without concerns for their cognitive abilities participating in the study. We also find other types of evidence in the data set. Our results should motivate caution in the use of large epidemiological study or survey-oriented data sets to build predictive models of clinical or subclinical pathologies without exploring or accommodating heterogeneity. Our results also suggest that one should include questions about motivation to participate in large epidemiological studies since different motivations may impact important relationships between independent and dependent variables.

Humans

Validation and refinement of a biomarker panel for frailty assessment and prediction of muscle weakness in older adults.

Frailty is a complex geriatric syndrome characterized by age-related declines in physiological function and cognitive reserve. To promote early prevention and intervention, minimally invasive and objective biomarkers that can detect frailty progression are required. We aimed to identify biomarkers associated with frailty progression and to elucidate their relevance to the Japanese version of the Cardiovascular Health Study (J-CHS) criteria, consist of five components (unintentional weight loss, self-reported exhaustion, muscle weakness, slow walking speed, and low physical activity). A total of 168 individuals (61 robust, 25 pre-frail, and 82 frail) enrolled in the NCGG (National Center for Geriatrics and Gerontology) Biobank were analyzed. Clinical information, blood-test data, aging-related factors, and gene-expression data were integrated for the analysis. First, linear regression identified one clinical factor, five aging-related factors, and 251 gene-expression factors associated with frailty. Subsequent logistic regression analyses examining each J-CHS components highlighted six candidate biomarkers. Cross-validation further suggested that three of these biomarkers-SMI, apelin, and GDF15-may represent potential biomarkers. Finally, retrospective and prospective analyses further demonstrated that those biomarkers were predictive of future muscle weakness, yielding a concordance index of 0.70. In conclusion, we validated and refined a biomarker panel consisting of SMI, apelin, and GDF15 that is associated with frailty, particularly muscle weakness (a major J-CHS component). These biomarkers may be useful for frailty assessment. Longitudinal analyses further suggested that they may be associated with the future development of muscle weakness in initially robust older adults, although validation in larger prospective cohorts is warranted.

Journal Article

Molecular hallmarks of excitatory and inhibitory neuronal resilience to Alzheimer's disease.

BACKGROUND: A significant proportion of individuals maintain cognition despite extensive Alzheimer's disease (AD) pathology, known as cognitive resilience. Understanding the molecular mechanisms that protect these individuals could reveal therapeutic targets for AD. METHODS: This study defines molecular and cellular signatures of cognitive resilience by integrating bulk RNA and single-cell transcriptomic data with genetics across multiple brain regions. We analyzed data from the Religious Order Study and the Rush Memory and Aging Project (ROSMAP), including bulk RNA sequencing (n&#x2009;=&#x2009;631 individuals) and multiregional single-nucleus RNA sequencing (n&#x2009;=&#x2009;48 individuals). Subjects were categorized into AD, resilient, and control based on &#x3b2;-amyloid and tau pathology, and cognitive status. We identified and prioritized protected cell populations using whole-genome sequencing-derived genetic variants, transcriptomic profiling, and cellular composition. RESULTS: Transcriptomics and polygenic risk analysis position resilience as an intermediate AD state. Only GFAP and KLF4 expression distinguished resilience from controls at tissue level, whereas differential expression of genes involved in nucleic acid metabolism and signaling differentiated AD and resilient brains. At the cellular level, resilience was characterized by broad downregulation of LINGO1 expression and reorganization of chaperone pathways, specifically downregulation of Hsp90 and upregulation of Hsp40, Hsp70, and Hsp110 families in excitatory neurons. MEF2C, ATP8B1, and RELN emerged as key markers of resilient neurons. Excitatory neuronal subtypes in the entorhinal cortex (ATP8B+&#x2009;and MEF2Chigh) exhibited unique resilience signaling through activation of neurotrophin (BDNF-NTRK2, modulated by LINGO1) and angiopoietin (ANGPT2-TEK) pathways. MEF2C+&#x2009;inhibitory neurons were over-represented in resilient brains, and the expression of genes associated with rare genetic variants revealed vulnerable somatostatin (SST) cortical interneurons that survive in AD resilience. The maintenance of excitatory-inhibitory balance emerges as a key characteristic of resilience. CONCLUSIONS: We have defined molecular and cellular hallmarks of cognitive resilience, an intermediate state in the AD continuum. Resilience mechanisms include preserved neuronal function, balanced network activity, and activation of neurotrophic survival signaling. Specific excitatory neuronal populations appear to play a central role in mediating cognitive resilience, while a subset of vulnerable interneurons likely provides compensation against AD-associated hyperexcitability. This study offers a framework to leverage natural protective mechanisms to mitigate neurodegeneration and preserve cognition in AD.

Humans

Impact of sex differences on microglial function in Alzheimer's disease.

Aging is the strongest risk factor for Alzheimer's disease (AD), a multifactorial neurodegenerative disorder characterized by amyloid-&#x3b2; (A&#x3b2;) accumulation, tau pathology (hyperphosphorylated tau and neurofibrillary tangles [NFTs]), and associated neuroinflammatory processes. Age-related cellular and molecular stressors, including mitochondrial dysfunction, genomic instability, and chronic low-grade inflammation, progressively increase vulnerability to neurodegeneration. In parallel, sex is increasingly recognized as a biological variable that shapes AD risk, clinical course, and neuropathological burden. Women account for roughly two-thirds of AD cases, a disparity not fully explained by longevity. Multiple factors likely contribute, including hormonal transitions across the lifespan (particularly menopausal estrogen decline), sex chromosome-linked immune regulation, sex-dependent interactions between genetic risk factors (e.g., APOE4 and TREM2) and brain aging, and differences in vascular risk, cognitive reserve, and sociocultural exposures that influence disease expression and detection. Microglia, the brain's resident immune cells, are sexually dimorphic, and respond to A&#x3b2; and tau pathology, modulating inflammatory signaling, synaptic remodeling, and neurovascular dysfunction implicated in AD. Emerging human and experimental evidence indicate that microglial activation states, immunometabolism, and functional responses differ between males and females and may contribute to sex-specific AD trajectories. Here, we synthesize current evidence supporting microglial sexual dimorphism across aging and AD, highlight possible candidates (hormonal signaling, immuno-aging, disease-associated microglial states, and immunometabolic remodeling), and discuss key knowledge gaps toward sex-informed precision approaches for prevention and treatment.

Humans

Impact of a multimodal prehabilitation program on postoperative cognitive dysfunction: a single-center randomized controlled trial.

BACKGROUND: Postoperative cognitive dysfunction (POCD) is a frequent complication after cardiac surgery. Exercise-based prehabilitation may enhance functional reserve and reduce vulnerability to perioperative cerebral insults. We hypothesized that multimodal prehabilitation reduces POCD 3&#xa0;months after cardiac surgery. METHODS: This prespecified substudy of a single-center randomized controlled trial (NCT03466606) included patients aged &#x2265;50&#xa0;years undergoing elective coronary artery bypass grafting and/or valve surgery. Participants were randomized 1:1 to 4-6&#xa0;weeks of multimodal prehabilitation (exercise training, nutritional support, and psychological support) or standard preoperative care. Cognitive function was assessed at baseline and 3&#xa0;months postoperatively using an age- and education-adjusted neuropsychological battery. POCD was defined as performance &#x2265;1.5 standard deviations below normative values in at least 2 cognitive tests, excluding the Mini-Mental State Examination. Logistic regression analyses were performed to evaluate factors associated with POCD. RESULTS: Of 160 participants screened from the parent trial, 134 met eligibility criteria for the substudy and were randomized; 116 completed 3-month follow-up (prehabilitation n&#xa0;=&#xa0;53; control n&#xa0;=&#xa0;63). POCD occurred in 29 patients (25%), including 15/53 (28%) in the prehabilitation group and 14/63 (22%) in controls (odds ratio [OR] 1.37, 95% confidence interval [CI] 0.54-3.50, P&#xa0;=&#xa0;0.52). In multivariable analysis, preoperative cognitive impairment was independently associated with POCD (OR 13.28, 95% CI 4.06-43.41, P&#xa0;<&#xa0;0.001), whereas prehabilitation was not (OR 1.09, 95% CI 0.35-3.45, P&#xa0;=&#xa0;0.877). Higher physical activity levels at 3&#xa0;months were associated with lower odds of POCD (OR 0.97, 95% CI 0.95-1.00, P&#xa0;=&#xa0;0.047). CONCLUSIONS: In this randomized controlled trial, a 4-6-week multimodal prehabilitation program did not reduce postoperative cognitive dysfunction 3&#xa0;months after cardiac surgery. Although the intervention did not achieve measurable cognitive protection, the observed association between postoperative physical activity levels and postoperative cognitive dysfunction warrants further investigation.

Humans

Assessment of cognitive organization in emotionally disturbed adolescents: a way of reducing parental perplexity?

Four adolescents of comparable age and IQ scores were described, two with primarily psychiatric diagnoses and two with additional CNS organic injuries. Despite the normal IQ scores, two had a combination of cognitive disabilities that make them highly suspect as being unable to manage their own affairs without the massive support usually reserved for the retarded population. Piaget's description of the cognitive abilities developed during the concrete operational stage of development were found to be invaluable in separating these more perplexing adolescents. Their inability to decenter, to reverse, to conserve, and to classify and abstract from this classification leads to a major series of cognitive defects and difficulties, difficulties that if not clarified for the parents, will leave them as perplexed as the professional working with these children.

Adolescent

Is construction reserved for the target during visual search?

This study was designed to examine the possibility, that where there is high similarity between irrelevant and target letters, the irrelevant letter will be constructed to sudents each attended a 1-hr. experimental session in which they searched 25 lists, followed by a recognition test. The lists were made up from the upper case letters of the alphabet, and during the recognition test each S was required to indicate how many times each of the irrelevant letters had appeared on the final list searched. Analysis of variance showed a significant recognition frequency effect. The results indicated Neisser's (1967) view, that during visual search construction is reserved for the target, may require modification.

Cognition

Can hyperbaric oxygenation improve cognitive functioning in the organically impaired elderly?: a critical review.

The present article reviews experimental investigation concerned with the effect of hyperbaric oxygenation upon cognitive functioning in the organically-impaired elderly. The conclusion of the Jacobs et al. studies was that hyperbaric oxygenation in cases of chronic organic brain damage (regardless of etiology) leads to improvement in cognitive functioning and general behavior on the ward. Goldfarb et al. (1972) found no evidence to support this conclusion. A critique of the above studies indicates several methodological weaknesses. First, there are serious reservations concerning the makeup of the samples employed in the Jacobs et al. (1969, 1971, 1972, 1973) investigations: it is highly uncertain that most of the Jacobs et al. subjects were suffering from moderate or severe chronic organic brain damage. One reason for the discrepancy between the Jacobs and Goldfarb studies is that the subjects in the later study were more deteriorated and perhaps not as amenable to hyperbaric oxygenation. Secondly, the Bender-Gestalt Test and Tien's Organic Integrity Test have not been validated in an elderly sample. The gain evidenced on the Stockton Geriatric Rating Scale (Jacobs et al., 1969, 1971, 1972) may have little practical significance, and since the data were pooled across groups, the so-called falloff effect could not have been measured. Third, and most significantly, the experimental designs employed in the Jacobs et al., the Goldfarb et al., and the Jacobs followup investigations have such serious shortcomings that the findings must be regarded as inconclusive. Such factors as experimenter attention, testing effects, and familiarity with the experimenter could account for the change in cognitive functioning. Further, in the case of the Jacobs et al. study, the ward personnel may have treated the control group differently after learning that they were expected to improve. Additionally, the subjects in the Jacobs et al. study (1969) themselves may have heard about this prognosis and may have become more interested in performing well on the psychological tests. Thuse, there is no unambiguous evidence that hyperbaric oxygenation was responsible for the changes or lack of changes in cognitive functioning in the samples presented in these studies.

Bender-Gestalt Test

NeuroOmics-Net: An interpretable multimodal deep learning framework for Alzheimer's disease diagnosis and progression prediction using neuroimaging, EEG, and genomic data.

Accurate diagnosis and progression prediction of Alzheimer's disease (AD) remain challenging due to the heterogeneous nature of the disease, which involves structural brain degeneration, electrophysiological dysfunction, and molecular dysregulation. Most existing deep learning approaches rely on a single modality or limited multimodal combinations, thereby failing to capture the complex cross-domain interactions underlying AD progression. Furthermore, the scarcity of large-scale datasets containing synchronized neuroimaging, electrophysiological, and genomic measurements restricts the development of comprehensive multimodal diagnostic systems. To address these challenges, this study proposes NeuroOmics-Net, a multimodal deep learning framework for Alzheimer's disease analysis that integrates structural magnetic resonance imaging (sMRI), electroencephalography (EEG), and gene expression data. The proposed framework combines a Hierarchical Multi-View Encoder (HME) for modality-specific feature extraction, a Cross-Omics Attention Fusion (CAF) module for adaptive integration of complementary biomarkers, and a Disease Progression Graph Learning (DPGL) module for modeling progression-related relationships across biological domains. To facilitate cross-modal integration from independent cohorts, Regularized Canonical Correlation Analysis (RCCA) is employed to align heterogeneous feature representations within a shared latent space. Experiments were conducted using publicly available datasets from ADNI, PhysioNet, and GEO repositories comprising 1120 diagnosis-aligned samples. The proposed framework achieved 94.3% classification accuracy and an AUC of 0.975 for distinguishing normal controls (NC), mild cognitive impairment (MCI), and Alzheimer's disease subjects, while attaining 93.7% accuracy for predicting conversion from stable mild cognitive impairment (sMCI) to progressive mild cognitive impairment (pMCI). However, a fairness sensitivity analysis using stratified demographic reweighting revealed accuracy ranging from 90.8% (low-education, high-comorbidity proxy subgroup) to 96.1% (low-risk, high-reserve proxy subgroup), a demographic parity gap of 5.3 percentage points, indicating that overall accuracy reflects a performance ceiling in a relatively homogeneous research cohort rather than a realistic estimate for demographically diverse clinical populations. Comparative evaluations demonstrated consistent improvements over state-of-the-art unimodal and multimodal deep learning models. Interpretability analysis further identified clinically relevant biomarkers, including hippocampal and entorhinal atrophy, theta-alpha EEG alterations, and APOE-associated molecular pathways. Because sMRI, EEG, and gene expression data were sourced from separate, unpaired cohorts with no subjects possessing all three synchronized measurements, all reported cross-modal associations reflect population-level statistical correspondence across diagnosis-matched groups rather than within-subject physiological coupling; no claim of intra-individual causal cross-modal interaction is made. These findings demonstrate that NeuroOmics-Net provides an effective computer-aided framework for multimodal biomedical data processing and Alzheimer's disease analysis. By integrating neuroimaging, electrophysiological, and genomic information, the proposed approach enables accurate diagnosis, progression prediction, and biologically interpretable decision support for clinical and translational applications.

Humans

A clinical guide to antipsychotic drugs.

Antipsychotic medications have altered the treatment of psychosis. The effect of typical agents is presumed to be associated with dopamine D2-receptor blockade. Response to these drugs can be evaluated by measuring target symptoms. Behavioural symptoms are generally first to respond, followed by affective symptoms, and then symptoms of disturbed cognition and perception. Predictors of response include age of onset, premorbid function, family history, cognitive function, ventricle size, and levels of homovanillic acid. As all conventional antipsychotic medications of comparable dose are generally of equivalent efficacy (with the exception of clozapine), choice is based on past response and the patient's tolerance of adverse effects. When antipsychotic agents are administered in the short term to control agitated dangerous behaviour, they can be given intramuscularly and augmented with benzodiazepines. For the ongoing treatment of psychosis, haloperidol 5 mg/day, or its equivalent, is usually sufficient. Continuation of treatment after an acute episode may be decided on the basis of chronicity of the psychotic illness. Relapse rates are higher when patients do not continue to receive medication. Lower maintenance doses may result in higher relapse rates but fewer adverse effects. Long-acting intramuscular depot preparations may be used to aid compliance in long term therapy. Adverse reactions correlate with potency. High potency drugs (i.e. those with greater D2 postsynaptic receptor affinity) are generally associated with extrapyramidal symptoms, including acute dystonic reactions, akathisia, tardive dyskinesia and Parkinsonism. Neuroleptic malignant syndrome is associated with all neuroleptic drugs. Low potency agents may cause orthostatic hypotension, sedation and anticholinergic effects. Clozapine has been shown to be effective in 30 to 40% of patients resistant to previous treatment. It does not cause extrapyramidal symptoms, but does have side effects similar to those of low potency agents and may cause agranulocytosis; it is therefore reserved for those patients who have not responded to therapy with 2 other agents. Several other atypical drugs are currently being investigated.

Antipsychotic Agents