POS1093 KNEE AND HIP OSTEOARTHRITIS ARE ASSOCIATED WITH SUBCLINICAL AND MANIFEST ATHEROSCLEROSIS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background:

An association between osteoarthritis (OA) and atherosclerosis (AT) has long been suggested, with its plausibility based on several guessed commonalities, from shared risk factors to overlapping molecular pathways, given that both conditions represent a state of chronic low-grade inflammation. However, meta-analyses of the impact of OA on hard cardiovascular (CV) endpoints have displayed conflicting results. Those disparate results probably stemmed from the heterogeneous OA population adjoined, as it has been postulated that OA denotes not a single, but a group of diseases with particular pathogenic mechanisms. Also, CV mortality may capture just the extreme of a continuum of atheromatous burden, and miss earlier subclinical disease.

Objectives:

In order to discern a more refined association between OA and AT, a systematic review and a meta-analysis of studies that focused on OA of weight-bearing joints (i.e., hip and knee) were performed, and the results stratified by clinical and subclinical AT.

Methods:

A search on PubMed, Web of Science, LILACS, and SciELO from inception until August 2020, was done using the MeSH search terms “osteoarthritis”, “aorta”, “carotid”, “intima-media thickness”, “coronary artery disease”, “atherosclerosis”, “cardiovascular disease”, and “death”. To appraise the quality of the studies, we applied the NewCastle-Ottawa scale. To assess for heterogeneity, I2 was used. A random-fixed effect model was adopted, and outliers were excluded when detected. Publication bias was ascertained qualitatively by funnel plot, and quantitatively by Egger regression test. Analyses were performed on RStudio version 1.3.1093.

Results:

The search retrieved 1335 citations, of which 168 were screened for abstract reading. From those, 127 were selected for full-text reading. After exclusion of duplicates and out of scope aricles, a total of 23 studies, comprising 151,187 individuals with OA and 287,444 controls, were included on the narrative synthesis, and 17 on the meta-analysis. All but one study were deemed as of fair or good quality. Fifteen studies found a positive association between OA and AT, the remaining 8 did not reach statistical significance. Four studies subdivided the OA patients by gender, and in half of those a positive association was found exclusively on females. Thirteen studies worked with a subclinical definition of AT, 1 included both subclinical and manifest disease, and the remainder included only manifest disease. Hip and knee OA increased the risk for both subclinical AT (OR 1.15, 95% CI 1.01-1.31, Figure 1A), and CV disease (OR 1.13, 95% CI 1.05-1.22, Figure 1B), but not for CV death (OR 1.08, 95% CI 0.99-1.19).

Conclusion:

Hip and knee OA are associated with AT. This may have practical implications on the management of OA patients, as a more intensive control of traditional CV risk factors may be advised.

Figure 1.

Forest plots showcasing the association between hip and knee OA and subclinical AT (A) and CV disease (B).

Acknowledgements:

Statistical analysis was performed under the supervision of Danielle Daffre Carvalho.

Disclosure of Interests:

None declared.

Capillaroscopy is a dynamic process in mixed connective tissue disease

To determine the clinical relevance of `scleroderma-pattern' (SD-pattern) in mixed connective tissue disease (MCTD), 63 (MCTD) patients (Kasukawa's criteria) were consecutively selected. The main inclusion criterion was availability of previous nailfold capillaroscopy (NC) five years before inclusion. At entry, organ involvement and autoantibody evaluation were performed. The mean age and disease duration were 45.3 ± 10 and 8.45 ± 5.42 years, respectively. SD-pattern was observed in 41 patients at entry (65%) and in 45 at previous NC (71.5%), P = 0.20. Ten patients (16%) changed NC, seven normalized, and three developed SD-pattern. Disease duration, number and frequency of organ involvement were similar in patients with and without SD-pattern. In contrast, analysis of each SD-pattern parameter revealed a significantly lower frequency of moderate/severe avascular areas (AA) at entry compared to previous examination (26.5 versus 53%, P = 0.013). Moreover, 76% of patients with interstitial lung disease (HRCT) had AA at entry, whereas only 24% of patients with this alteration did not have this NC finding ( P = 0.017). Furthermore, reduced capillary density was more frequently observed in patients taking immunosuppressive therapy than in those without this medication (66.7 versus 33.3%, P = 0.001). NC in MCTD is a dynamic process and analysis of each SD-pattern parameter seems to be a good indicator of lung involvement and disease severity. Lupus (2007) 16, 254—258.

Joint loading decreased by inexpensive and minimalist footwear in elderly women with knee osteoarthritis during stair descent

OBJECTIVE

Previous studies indicate that flexible footwear, which mimics the biomechanics of walking barefoot, results in decreased knee loads in patients with knee osteoarthritis (OA) during walking. However, the effect of flexible footwear on other activities of daily living, such as descending stairs, remains unclear. Our objective was to evaluate the influence of inexpensive and minimalist footwear (Moleca) on knee adduction moment (KAM) during stair descent of elderly women with and without knee OA.

METHODS

Thirty-four elderly women were equally divided into an OA group and a control group (CG). Stair descent was evaluated in barefoot condition, while wearing the Moleca, and while wearing heeled shoes. Kinematics and ground reaction forces were measured to calculate KAM by using inverse dynamics.

RESULTS

The OA group experienced a higher KAM during midstance under the barefoot condition (233.3%; P = 0.028), the Moleca (379.2%; P = 0.004), and heeled shoes (217.6%; P = 0.007). The OA group had a similar knee load during early, mid, and late stance with the Moleca compared with the barefoot condition. Heeled shoes increased the knee loads during the early-stance (versus barefoot [16.7%; P < 0.001] and versus the Moleca [15.5%; P < 0.001]), midstance (versus barefoot [8.6%; P = 0.014] and versus the Moleca [9.5%; P = 0.010]), and late-stance phase (versus barefoot [10.6%; P = 0.003] and versus the Moleca [9.2%; P < 0.001]). In the CG, the Moleca produced a knee load similar to the barefoot condition only during the early-stance phase.

CONCLUSION

Besides the general foot protection, the inexpensive and minimalist footwear contributes to decreasing knee loads in elderly women with OA during stair descent. The loads are similar to the barefoot condition and effectively decreased when compared with heeled shoes.

Is short-term remediation after OSCE failure sustained? A retrospective analysis of the longitudinal attainment of underperforming students in OSCE assessments

BACKGROUND

Significant improvements in the delivery of criterion-based assessment techniques have improved confidence in standard setting and assessment quality. However, for underperforming students, a lack of evidence about longitudinal performance of this group poses dilemmas to educators when making decisions about the timing and nature of remediation.

AIM

To investigate the longitudinal performance of the UK undergraduate medical degree students, with a particular focus on comparing the poorly performing students (i.e. those with borderline or failing grades) with the main cohort of students.

METHOD

Over a 5-year period, 3200-student objective structured clinical examination (OSCE) assessments from a single medical school were investigated. A poorly performing subgroup of 125 students was identified and their longitudinal performance in the final 3 years of the undergraduate medical degree analysed.

RESULT

The relative performance of this student group declines across serial OSCEs, despite current methods of 'remediation and retest'.

CONCLUSIONS

This analysis demonstrates that typically students in the poorly performing subgroup achieve only short-term success with traditional remediation and retest models, and critically show an absence of longitudinal improvement. There is a clear need for institutions to develop profiling models that can help identify this student group and develop effective, research led models of remediation.

Collaboration across the pond: the multi-school progress testing project

This collaborative project between the National Board of Medical Examiners and four schools in the UK is investigating the feasibility and utility of a cross-school progress testing program drawing on test material recently retired from the United States Medical Licensing Examination (USMLE) Step 2 Clinical Knowledge (CK) examination. This article describes the design of the progress test; the process used to build, translate (localize), review, and finalize test forms; the approach taken to (web-based) test administration; and the procedure used to calculate and report scores. Results to date have demonstrated that it is feasible to use test items written for the US licensing examination as a base for developing progress test forms for use in the UK. Some content areas can be localized more readily than others, and care is clearly needed in review and revision of test materials to ensure that it is clinically appropriate and suitably phrased for use in the UK. Involvement of content experts in review and vetting of the test material is essential, and it is clearly desirable to supplement expert review with the use of quality control procedures based on the item statistics as a final check on the appropriateness of individual test items.

The frequency of anti-β2-glycoprotein I antibodies is low and these antibodies are associated with pulmonary hypertension in mixed connective tissue disease

The objective of this study is to evaluate the prevalence of antiphospholipid antibodies, mainly anti-β2-glycoprotein I (anti-β2-GPI), and their possible clinical and laboratory relevance in mixed connective tissue disease (MCTD). This study included 39 consecutive patients with MCTD (Kasukawa’s criteria) from January, 2005, to March, 2007, and compared them with 21 age- and sex-matched healthy controls. IgG and IgM anticardiolipin (aCL) and anti-β2-GPI were measured by ELISA. Lupus anticoagulant (LA) was detected by functional coagulation tests. Medium to high titres of aCL and anti-β2-GPI antibodies were found in sera from four (10.2%) MCTD patients. One of these patients was found to be positive for IgM aCL, IgM anti-β2-GPI and LA antibodies simultaneously. Additionally, this patient had a previous history of foetal loss in the second trimester and new-onset pulmonary arterial hypertension (PAH). The other three patients had none of the manifestations of antiphospholipid syndrome (APS) or PAH. The mean value of IgG anti-β2-GPI was higher among those MCTD patients with PAH than in the group without PAH (34.2 ± 46.8 vs 12.3 ± 9.1, P = 0.018). None of the controls were positive for antiphospholipid antibodies. High to moderate titres of anti-β2-GPI as well as APS were rare in MCTD, and these antibodies may be correlated with the development of PAH in these patients.

Impact of speed change on estimated journey time: failure of drivers to appreciate relevance of initial speed

Higher speeds are associated with increases in the probability of crashing and the severity of the outcome. Logically drivers speed to save time, and research evidence supports this assertion. It is therefore important to investigate drivers' understanding of how speed change impacts on journey time. Since it is likely that drivers do not appreciate the reciprocal nature of the function which links these two variables, and its implications, two predictions can be made: the impact of a speed change will be underestimated at low speeds and overestimated at high speeds. This issue was addressed through four questions generated by manipulating Speed Change (increase versus decrease) and Starting Speed (30 mph versus 60 mph) with the participants being asked how they felt these variables would impact on journey time. These were included in a large survey addressing speed-related issues. Participants were a representative quota sample of 1005 UK drivers, interviewed by questionnaire. The findings indicated that three of the four questions produced results consistent with the predictions made. Furthermore, a repeated measures factorial ANOVA indicated that there was no real appreciation of how starting speed impacted on journey time. A disordinal interaction provided evidence that drivers wrongly believed that as starting speed increased the impact of a speed rise also increased; the opposite is true. For speed decreases, drivers appeared to think that starting speed had little impact on the amount of time saved. It is recommended that these findings be integrated into driver training and speed awareness courses.

A preliminary investigation of the running digit span as a test of working memory

The objective of this study was to compare performance on different versions of the running span task, and to examine the relationship between task performance and tests of episodic memory and executive function. We found that the average capacity of the running span was approximately 4 digits, and at long sequence lengths, performance was no longer affected by varying the running span window. Both episodic and executive function measures correlated with short and long running spans, suggesting that a simple dissociation between immediate memory and executive processes in short and long running digit span tasks may not be warranted.

'Rules of thumb' or reflective practice? Understanding senior physicians' decision-making about anti-thrombotic usage in atrial fibrillation

BACKGROUND

The recently published Atrial Fibrillation (AF) Guidelines from the National Institute for Health and Clinical Excellence (NICE) highlight the importance of assessing stroke risk and using appropriate anti-thrombotic therapy.

AIM

To improve understanding of physicians' behaviour and attitudes in respect to decision-making in AF and the use of anti-thrombotics.

DESIGN

Semi-qualitative, questionnaire- and interview-based study.

METHODS

Five clinical vignettes relating to treatment choices for AF and stroke prevention illustrating a range of risk and benefit were examined by 14 senior physicians (consultants or specialist registrars) in Cardiology, General Medicine and Geriatric Medicine, who then recommended anti-thrombotic treatment. A semi-structured interview explored their decision-making and prescribing in AF, with qualitative analysis of interview transcripts using grounded theory.

RESULTS

There was marked variation in the choice of anti-thrombotic treatment. Respondents were more likely to prescribe warfarin to patients with a previous intracerebral haemorrhage than to a patient with a history of falls. A key theme on qualitative analysis revealed that decision-making in AF is often associated with uncertainty and concerns about knowledge of risk and benefit.

DISCUSSION

In this study, doctors rarely agreed on the choice of anti-thrombotics in AF, and their perceptions of stroke and bleeding risk showed considerable variation. Uncertainty, doubt, concerns about knowledge and varied approach to the role of patients in decision-making are all significant themes in the considerable variability in anti-thrombotic prescribing.

Random number generation as an index of controlled processing

Random number generation (RNG) is a functionally complex process that is highly controlled and therefore dependent on Baddeley's central executive. This study addresses this issue by investigating whether key predictions from this framework are compatible with empirical data. In Experiment 1, the effect of increasing task demands by increasing the rate of the paced generation was comprehensively examined. As expected, faster rates affected performance negatively because central resources were increasingly depleted. Next, the effects of participants' exposure were manipulated in Experiment 2 by providing increasing amounts of practice on the task. There was no improvement over 10 practice trials, suggesting that the high level of strategic control required by the task was constant and not amenable to any automatization gain with repeated exposure. Together, the results demonstrate that RNG performance is a highly controlled and demanding process sensitive to additional demands on central resources (Experiment 1) and is unaffected by repeated performance or practice (Experiment 2). These features render the easily administered RNG task an ideal and robust index of executive function that is highly suitable for repeated clinical use.

Atrial fibrillation: will new drugs and patient choice improve anticoagulation outcomes?

The growing epidemic of atrial fibrillation presents major challenges to the healthcare community, both clinical and financial.

Older people's understanding of cumulative risks when provided with annual stroke risk information

Understanding how cumulative health risks increase over time constitutes an important part of decision making about treatment risks and benefits. In this study, wide ranging perceptions of cumulative risk led to significant overestimation and underestimation of risks over time. Time has shown to significantly impact on the personal interpretation of cumulative risk information by patients, with many subjects struggling to understand the concept of cumulative risks. This suggests that a careful explanation of the effect of cumulative risk over time to patients should contribute to more effective decision making.

How informed is consent? Understanding of pictorial and verbal probability information by medical inpatients

Understanding probability information about treatment risks and benefits is a vital component of patients' decision making capacity. This study demonstrates extensive misunderstanding of verbal descriptions of probability by medical inpatients of all ages, questioning the extent of their capacity for giving informed consent. Pictorial descriptions of probability were well understood, suggesting their adoption into clinical practice.

A comparison of different biogeographical classifications of Europe, Great Britain and Spain

Various biogeographical and bioclimatic classifications of a number of regions, countries and continents have been created to meet different objectives. A policy maker might ask the question 'why is there no single accepted classification and how do the different classifications compare with one another?' In order to answer these two questions three classifications created by different methods for Great Britain and two for Spain are compared using the Kappa statistic. All of the classifications were created from data on cellular grids with a set window size. Further non-statistical comparisons are made with other classifications. The biogeographic classifications studied in this paper produced three different types of zone: those that were always identified whatever the method; those that were broadly similar but where the boundaries differed; and those that were unique to a particular classification. These different types of zone are likely to exist for any comparison between classifications of a particular region. The extent of the geographic window from which data were obtained had a major effect on the classification of grid cells at the edges of the window. For example, the few grid cells in the south of England, with characteristics of continental Europe, are not detected if data from Great Britain alone are used for the classification. We conclude that the data window should always be larger than the area for which the classification is being made. The objective Kappa statistic, although useful, was not capable of discerning similarities and dissimilarities that appear obvious to the subjective human eye. Although the details of the classifications differed there were broad similarities between the classifications and these differences reflect important divisions along major environmental axes that have been inferred by earlier biogeographers. As the divisions are real there is a sound basis for their use in future land use or environmental policy.

Risk communication and older people-understanding of probability and risk information by medical inpatients aged 75 years and older

OBJECTIVE

To determine older people's understanding of probability and risk information, and the impact of pictorial representation of risk.

DESIGN

A researcher-administered questionnaire.

SUBJECTS

50 inpatients aged > or =75 years on elderly medicine wards at Huddersfield Royal Infirmary, Huddersfield, UK.

RESULTS

Older people understand percentage probability better than fractional probability, and a wide range of incorrect responses indicated significant over- and underestimation of probabilities. Visual data about percentages were well received and understood, and were perceived as a good idea by participants.

CONCLUSIONS

We have demonstrated a wide variation in understanding of risk and probability information by older people, with over- and underestimations of probability, along with confusion between fractional and percentage probability. Pictorial representation of probability was well understood. It could be developed as a simple, yet powerful communication tool to be used in daily clinical practice to help older people understand information on risks and benefits when making decisions about treatment choices.

Impairment of movement initiation and execution but not preparation in idiopathic dystonia

Imaging studies have reported impaired activation of the striatum and their frontal projection sites in dsytonia, areas which are considered to play a role in motor preparation, movement initiation and execution. The aim of this study was to investigate the processes of motor preparation, response initiation and execution in patients with idiopathic torsion dystonia (ITD). We assessed 12 patients with ITD and 12 age-matched controls on a number of reaction time (RT) tasks that differed in degree of motor preparation possible. Subjects performed a visual simple RT (SRT) task, an uncued four-choice reaction time (CRT) task and a fully precued four-choice RT task. A stimulus 1-stimulus 2 (S1-S2) paradigm was used. The warning signal/precue (S1) preceded the imperative stimulus (S2) by either 0 ms (no warning signal or precue) 200 ms, 800 ms, 1,600 ms or 3,200 ms. The patients with ITD had significantly slower RTs and movement times than normals across all RT tasks. The unwarned SRT trials were significantly faster than the uncued CRT trials for both groups. For both groups, precued CRTs were significantly faster than the uncued CRTs. The results show that while response initiation and execution are significantly slower in patients with ITD than normals, movement preparation is not quantitatively or qualitatively different. The results are discussed in relation to previous imaging, behavioural and electrophysiological studies and models of fronto-striatal dysfunction in ITD.

Lactic acid bacteria and their effect on the immune system

Lactic acid bacteria (LAB) are present in the intestine of most animals. The beneficial role played by these microorganisms in the humans and other animals, including the effect on the immune system, has been extensively reported. They are present in many foods and are frequently used as probiotics to improve some biological functions in the host. The activation of the systemic and secretory immune response by LAB requires many complex interactions among the different constituents of the intestinal ecosystem (microflora, epithelial cells and immune cells). Through different mechanisms they send signals to activate immune cells. Thus the knowledge of the normal intestinal microflora, the contribution of LAB and their role in the numerous functions in the digestive tract as well as the functioning of the mucosal immune system form the basis for the study and selection of a probiotic strain with immunostimulatory properties. In the selection of LAB by their immunostimulatory capacity it helps to know not only the effect which they have on the mucosal immune system, but the specific use to which these oral vaccine vectors are being put. Although there are reports of the protection of animals and humans against diseases such as microbial infections and cancer, more work remains to be done on the factors affecting the design of oral vaccine vectors and the use of LAB for therapeutic purposes. The basic knowledge of LAB immunostimulation and the criteria for selection of LAB by their immunostimulatory capacity, will be extensively discussed and appraised in this review.

The role of the dorsolateral prefrontal cortex in random number generation: a study with positron emission tomography

Random number generation (RNG) engages a number of executive processes. We used positron emission tomography (PET) to measure regional cerebral blood flow (rCBF) in six volunteers who performed RNG and a control counting (COUNT) task at six rates paced by a tone. This provided a systematic variation of difficulty of RNG. Relative to COUNT, RNG was associated with significant activation of the left dorsolateral prefrontal cortex (DLPFC), the anterior cingulate, the superior parietal cortex bilaterally, the right inferior frontal cortex, and the left and right cerebellar hemispheres. Faster rates of RNG were associated with a significant decrease in regional cerebral blood flow (rCBF) in the left and right DLPFC and the right superior parietal cortex. rCBF in the left DLPFC was significantly and negatively associated with count score 1, a measure of habitual counting during RNG. These results are discussed in relation to the network modulation model of RNG developed on the basis of our previous studies using transcranial magnetic stimulation and dual task paradigms. This suggests that during RNG, suppression of habitual counting is achieved through the modulatory (inhibitory) influence of the left DLPFC over a number associative network distributed in the superior temporal cortex. At faster rates of RNG the synchronization demands of paced RNG result in the breakdown of this modulatory influence, which is evident from decreased rCBF in the left DLPFC and increased habitual counting at faster rates.

Methods for the generation of chicken monoclonal antibody fragments by phage display

Phage display has become an important approach for the preparation of monoclonal antibodies from both immune and nonimmune sources. This approach allows for the rapid selection of monoclonal antibodies without the restraints of the conventional hybridoma approach. Although antibodies to a wide variety of antigens have been selected using phage display, some highly conserved mammalian antigens have proven to be less immunogenic in mammalian animals commonly used for immunization. In order to optimize methods for constructing chicken immunoglobulin phage display libraries in the pComb3 system, we have immunized chickens with the hapten fluorescein, and generated combinatorial antibody libraries from spleen and bone marrow RNA. Herein we present methods for the isolation of scFv, diabody and Fab fragment libraries from chickens. Chicken Fab fragment libraries are constructed using human constant regions, facilitating detection with readily available reagents as well as humanization. Analysis of the selected V-genes revealed that gene conversion events were more extensive in light-chain variable region genes as compared to heavy-chain variable region genes. In addition, we present a new variant of the pComb3 phage display vector system.

Using antibody catalysis to study the outcome of multiple evolutionary trials of a chemical task

Catalytic aldolase antibodies generated by immunization with two different, but structurally related, beta-diketone haptens were cloned and sequenced to study similarities and differences between independently evolved catalysts. Kinetic and sequence analysis coupled with mutagenesis, structural, and modeling studies reveal that the defining event in the evolution of these catalysts was a somatic mutation that placed a lysine residue in a deep, yet otherwise unrefined, hydrophobic pocket. We suggest that covalent chemistries may be as readily selected from the immune repertoire as the traditional noncovalent interactions that have formed the basis of immunochemistry until this time. Further, we believe that these experiments recapitulate the defining events in the evolution of nature's enzymes, particularly as they relate to chemical mechanism, catalytic promiscuity, and gene duplication.

Survey of the cross-cultural content of U.S. psychiatry residency training programs

To establish the extent of cross-cultural content contained in the 224 psychiatric residency training programs, the Directors of Residency Training were surveyed by mail. Thirty-seven percent (N = 83) of Directors responded; 92% (N = 76) had cross-cultural content, 99% (N = 82) had opportunities to work with minority patients, and 77% (N = 64) had supervision by some minority faculty. Responding programs reported a need for teaching videotapes (85%, N = 71), cross-cultural references (78%, N = 65), academic psychiatrists familiar with different cultural groups (76%, N = 63), and cross-cultural supervision (75%, N = 62).

Aspects of in vitro and in vivo research approaches directed toward identifying probiotics and prebiotics for human use

The microbiota of the human gastrointestinal tract plays a key role in nutrition and health. Through the process of fermentation, gut bacteria metabolize various substrates (principally dietary components) to end products such as short-chain fatty acids and gases. This anaerobic metabolism is thought to contribute positively toward host daily energy requirements. However, under certain circumstances, the fermentative process may produce undesirable metabolites. This may cause the onset of gut disorders that can be manifest through both acute and chronic conditions. Moreover, the gut flora may become contaminated by transient pathogens that serve further to upset the normal community structure. There has been a recent increase in the use of dietary components that help to maintain, or even improve, the gut microflora "balance." Probiotics are live microbial feed supplements added to appropriate food vehicles (usually fermented milks), whereas prebiotics are dietary carbohydrates that have a selective metabolism in the colon and serve to increase numbers of bacteria seen as desirable. Because of their purported health-promoting properties, lactic acid-producing bacteria, including bifidobacteria, are the usual target organisms. The market value and biological potential of both approaches are enormous. This article will summarize how efficacious types can be identified.

Movement-related potentials prior to self-initiated movements are impaired in patients with schizophrenia and negative signs

It has been suggested that certain symptoms of schizophrenia such as poverty of action and speech, and stereotyped action, reflect a dysfunction of "willed" actions while the processes involved in "stimulus-driven" actions remain intact. The aim of this study was to test this hypothesis by measuring movement-related potentials (MRPs) prior to self-initiated and externally triggered movements in three groups of subjects, five patients with a diagnosis of schizophrenia with high ratings of negative signs, six patients with a diagnosis of schizophrenia with high ratings of positive symptoms and six normal controls. Subjects lifted their right index finger at an average rate of once every 3 s in two conditions, either as self-initiated movements, or as a response to a tone while MRPs were recorded from frontal, frontocentral, central and parietal sites. The patients with schizophrenia and high ratings of negative signs had reduced amplitude of MRPs for the late and peak component and reduced slope of the early and late MRPs prior to self-initiated movements. These differences were not found prior to externally triggered movements. The patients with schizophrenia with higher ratings of positive symptoms did not differ significantly from the normal controls in terms of amplitude or slope of MRPs prior to self-initiated or externally triggered movements. These findings support the proposal that patients with schizophrenia, particularly those with negative signs, show impairment of willed actions but are not impaired in externally triggered movements. These deficits in willed actions may be mediated by impaired functioning of the frontostriatal loops.

Concurrent performance of motor tasks and processing capacity in patients with schizophrenia

Any task is carried out more successfully if we allocate undivided attention to it, but as demands on attentional capacity increase-for example, in concurrent or dual task conditions-performance on attended tasks becomes more impaired. Patients with schizophrenia show impaired performance on tasks requiring high levels of attentional capacity. This study examines performance of 11 patients with schizophrenia and 13 normal controls on two motor tasks (placing pegs in a pegboard and repetitive index finger tapping) under unimanual, bimanual, and dual task conditions. The patients with schizophrenia placed fewer pegs and had reduced tapping speed in unimanual and bimanual conditions. However, the decrement in bimanual performance as a percentage of unimanual performance was not significantly different for the patients and controls on either the pegboard or tapping tasks. By contrast, under dual task conditions, the performance of the patients with schizophrenia in peg placement actually improved relative to the unimanual pegboard task, whereas tapping performance deteriorated compared with the unimanual tapping, a decrement that was significantly greater for the patients. Thus the improvement in the visually guided pegboard task was at the expense of the repetitive tapping task. These results are discussed in terms of an impairment of self initiated movement with general sparing of externally triggered movements in schizophrenia and the role of frontostriatal loops in this process.

Impairment of willed actions and use of advance information for movement preparation in schizophrenia

OBJECTIVES

To assess willed actions in patients with schizophrenia using reaction time (RT) tasks that differ in the degree to which they involve volitionally controlled versus stimulus driven responses.

METHODS

Ten patients diagnosed with schizophrenia and 13 normal controls of comparable age were tested. Subjects performed a visual simple RT (SRT), an uncued four choice reaction time (CRT), and a fully cued four choice RT task. A stimulus 1(S1)-stimulus 2(S2) paradigm was used. The warning signal/precue (S1) preceded the imperative stimulus (S2) by either 0 (no warning signal or precue) 200, 800, 1600, or 3200 ms.

RESULTS

The patients with schizophrenia had significantly slower RTs and movement times than normal subjects across all RT tasks. The unwarned SRT trials were significantly faster than the uncued CRT trials for both groups. For both groups, fully cued CRTs were significantly faster than the uncued CRTs. However, the S1-S2 interval had a differential effect on CRTs in the two groups. For the normal subjects fully cued CRTs and SRTs were equivalent when S1-S2 intervals were 800 ms or longer. A similar pattern of effects was not seen in the patients with schizophrenia, for whom the fully cued CRT were unexpectedly equivalent to SRT for the 200 ms interval and expectedly for the 1600 ms S1-S2 interval, but not the 3200 or 800 ms intervals.

CONCLUSIONS

Patients with schizophrenia were able to use advance information inherent in SRT or provided by the precue in fully cued CRT to speed up RT relative to uncued CRT. However, in the latter task, in which the volitional demands of preprogramming are higher since a different response has to be prepared on each trial, patients showed some unusual and inconsistent interval effects suggesting instability of attentional set. It is possible that future studies using RT tasks with higher volitional demands in patients with predominance of negative signs may disclose greater deficits in willed action in schizophrenia.