Bleuler revisited: psychomotor slowing in schizophrenia as part of a catatonic symptom cluster

Digging deeper in the differential effects of inflammatory and psychosocial stressors in remitted depression: Effects on cognitive functioning

BACKGROUND

Major Depressive Disorder (MDD) covers a wide spectrum of symptoms, including cognitive dysfunction, which can persist during remission. Both inflammatory states and psychosocial stress play a role in MDD pathogenesis.

METHODS

The effects of inflammatory (i.e., Salmonella typhi vaccine) and psychosocial stressor (i.e., Trier Social Stress Test), as well as their combination were investigated on cognition in women (aged 25-45 years, n = 21) with (partially) remitted MDD and healthy controls (n = 18) in a single-blind placebo-controlled study. In a crossover design, patients received on the first day one of the aforementioned interventions and on the other day a placebo, or vice versa, with a washout period of 7-14 days. Short-term and verbal memory, working memory, attention, verbal fluency, information processing speed, psychomotor function, and measures of attentional bias to emotions were measured. Exploratory analyses were performed to assess the correlation between biomarkers of inflammation and the Hypothalamic-Pituitary-Adrenal axis and cognitive functioning.

RESULTS

In patients, inflammatory stress decreased information processing speed and verbal memory, and increased working memory; after psychosocial stress, there was an increase in attention. There was also an increased negative attentional bias in patients after inflammatory stress. Neither stressor had any effect in controls.

LIMITIATIONS

Limitations are the relatively small sample size and antidepressant use by a part of the participants. The effects of the stressors were also measured a relatively short period after administration.

CONCULSION

Patients were sensitive to the cognitive effects of inflammation and psychosocial stress on cognition, while controls were not.

Asymmetries in initiation of aiming movements in schizophrenia

Several studies have reported motor symptoms in schizophrenia (SCZ), in some cases describing asymmetries in their manifestation. To date, biases were mainly reported for sequential movements, and the hypothesis was raised of a dopamine-related hemispheric imbalance. Aim of this research is to better characterize asymmetries in movement initiation in SCZ by exploring single actions. Fourteen SCZ patients and fourteen healthy subjects were recruited. On a trial-by-trial basis, participants were instructed to reach for one of eight possible targets. Measures of movement initiation and execution were collected. Starting point, target and moving limb were systematically varied to check for asymmetric responses. Results showed that SCZ patients, besides being overall slower than controls, additionally presented with a bias affecting both the moving hand and the side from which movements were initiated. This finding is discussed in relation to hemispheric lateralization in motor control.

Unraveling psychomotor slowing in bipolar disorder

BACKGROUND/AIMS

In addition to affective and cognitive symptomatology, psychomotor deficits are known to be present in bipolar disorder (BD). Psychomotor functioning includes all of the processes necessary for completing a movement, from planning to initiation and execution. While these psychomotor symptoms have been studied extensively in schizophrenia and major depressive disorder, only simple measures have been conducted in BD. The present study examines psychomotor functioning in BD.

METHODS

Twenty-two euthymic BD patients and 21 healthy controls performed three computerized copying tasks varying in cognitive load. Movement times (MT), reflecting fine motor processing, and initiation times (IT), reflecting cognitive processing of visual-spatial information, were separately measured in each group.

RESULTS

The BD patients had longer IT but not MT in the simplest task and the opposite pattern of longer MT but not IT in the complex task. However, when controlling for residual mood symptoms, the MT were no longer significantly slower in the BD group.

CONCLUSIONS

The longer MT and IT in BD reflect overall psychomotor slowing. Specifically, the results provide evidence for cognitive slowing in BD. In addition, the longer MT in the complex task reflect a slowed motor component of movement when the cognitive load is high and when depressive symptoms are present. These findings extend the current knowledge of the nature of psychomotor slowing in BD and may have important prognostic implications for patients.

Conflict adaptation in schizophrenia: reviewing past and previewing future efforts

INTRODUCTION

Cognitive control impairments have been suggested to be a critical component in the overall cognitive deficits observed in patients diagnosed with schizophrenia. Here, we zoom in on a specific function of cognitive control, conflict adaptation. Abnormal neural activity patterns have been observed for patients diagnosed with schizophrenia in core conflict adaptation areas such as anterior cingulate cortex and prefrontal cortex. On the one hand, this strongly indicates that conflict adaptation is affected. On the other hand, however, outcomes at the behavioural level are needed to create a window into a precise interpretation of this abnormal neural activity.

METHODS

We present a narrative review of behavioural work within the context of conflict adaptation in schizophrenia, focusing on various major conflict adaptation markers: congruency sequence effects, proportion congruency effects, and post-error and post-conflict slowing. The review emphasises both methodological and theoretical aspects that are relevant to the understanding of conflict adaptation in schizophrenia.

RESULTS

Based on the currently available set of behavioural studies on conflict adaptation, no clear-cut answer can be provided as to the precise conflict adaptation processes that are impaired (and to what extent) in schizophrenia populations.

CONCLUSIONS

Future work is needed in state-of-the-art designs in order to reach better insight into the specifics of conflict adaptation impairments associated with schizophrenia.

Motor behavior reflects reduced hemispheric asymmetry in the psychosis risk period

BACKGROUND

A body of work focusing on brain connectivity, language dominance, and motor laterality research suggests that reduced hemispheric asymmetry is a core feature in schizophrenia. However, there is little consensus about whether reduced dominance is present in those at ultrahigh risk (UHR) for psychosis.

METHODS

A total of 94 demonstrated right-handed neuroleptic free participants (38 UHR and 56 matched healthy controls) were assessed with structured clinical interviews and completed an innovative handwriting task using a digital tablet computer. A laterality quotient (LQ) was calculated using kinematic variables from the participant's left and right hands. A subset of the sample (26 UHR and 29 controls) returned after 12-months to complete clinical interviews in order to examine relationships between handwriting laterality and progression of psychosis risk symptoms.

RESULTS

The UHR group showed decreased dextrality compared to healthy controls. At the 12-month follow-up, decreased dextrality accounted for 8% of the variance in worsened positive symptoms within the UHR group.

CONCLUSION

The current results suggest that disrupted cerebral dominance is also present in the ultrahigh risk period and that decreased dextrality may serve as a novel biomarker for the progression of psychosis risk.

Neurophysiological evidence for diminished monitoring of own, but intact monitoring of other's errors in schizophrenia

Schizophrenia is characterized by social deficits. Correctly monitoring own and others' performance is crucial for efficient social behavior. Deficits in monitoring own performance as reflected in reduced error-related negativity (rERN) amplitudes, have been demonstrated repeatedly in schizophrenia. A similar ERP component (observed ERN; oERN) is elicited when observing others' mistakes. However, possible deficits in monitoring others' performance have never been investigated in schizophrenia. The current ERP-study compared a group of schizophrenia patients (N=22) and healthy controls (N=21) while performing a Simon task and the social Simon task, enabling the investigation of own (rERN) and others' (oERN) performance monitoring. Patients showed slower reaction times, but comparable accuracy and compatibility effects in both tasks. As expected, patients' rERN amplitudes were reduced. Importantly however, oERN amplitudes were comparable between both groups. While monitoring own performance is compromised in schizophrenia, monitoring others' performance seems intact. This divergence between internal and external performance monitoring in patients is in line with studies showing normal neurophysiological responses to negative feedback. The presently found dissociation may improve our understanding of cognitive and neural mechanisms underlying monitoring of own and others' performance and may stimulate treatment development aimed at learning from external rather than internal error information in schizophrenia.

Catatonia as part of the psychomotor syndrome in schizophrenia

Although the prevalence and severity of catatonia may have decreased over time, it is still a highly relevant, frequently occurring symptom cluster that can be observed in schizophrenia patients. Apart from this syndrome, neurological soft signs, psychomotor slowing and extrapyramidal symptoms are other psychomotor symptom clusters that are part of the clinical picture of schizophrenia. In this overview, the relevance of catatonia as a contemporary symptom cluster of the illness as well as its relationship with other psychomotor symptoms of the illness are discussed.

Spontaneous parkinsonisms and striatal impairment in neuroleptic free youth at ultrahigh risk for psychosis

Background:

Spontaneous movement abnormalities, occurring independent of medication status, are thought to reflect basal ganglia pathology in patients at ultrahigh risk (UHR) for psychosis. To date, the research literature has primarily focused on movements associated with elevated striatal dopamine (i.e., hyperkinesia) while little is known about motor symptoms associated with low levels of subcortical dopamine (i.e., spontaneous parkinsonisms; SPs). As SPs (e.g., bradykinesia) may be governed by distinct neural mechanisms, this line of research can provide a clearer picture of the etiological processes in the prodrome.

Aims:

To examine SPs and striatal structural correlates in youth at risk for psychosis.

Methods:

A total of 81 (35 UHR, 46 healthy controls) adolescents were administered a structured clinical interview, structural MRI scan, and handwriting kinematic analysis capable of assessing SPs that are not detectable by traditional observer-based inventories.

Results:

The UHR group exhibited significant decreased velocity scaling (indicative of SPs), t(79)=−2.65, P⩽0.01, as well as decreased ipsilateral t(68)=−3.16, P⩽0.001 and contralateral t(68)=−3.32, P⩽0.001 putamen volume compared with the healthy control group. Further, decreased velocity scaling was significantly associated with smaller ipsilateral putamen r(68)=0.23, P⩽0.05, 95% confidence interval (CI) (−0.005, 0.44), left r(68)=0.23, P⩽0.05, 95% CI (−0.005, 0.44) and right r(68)=0.21, P⩽0.05, 95% CI (−0.03, 0.42) caudate volume, as well as increased positive r(79)=−0.20, P=0.05, 95% CI (−0.40, −0.02) and negative r(79)=−0.27, P⩽0.05, 95% CI (−0.46, −0.06) symptoms across the sample.

Conclusions:

These findings represent the first evidence for hypokinetic movement abnormalities in the UHR period, indicating that pathophysiological processes in UHR patients may also involve hypodopaminergia. The results implicate a dopamine-induced imbalance contributing to frontal–subcortical circuit dysfunction in the psychosis prodrome.

The nature of the relationship of psychomotor slowing with negative symptomatology in schizophrenia

INTRODUCTION

Psychomotor slowing is an important feature of schizophrenia and the relation with negative symptoms is not fully understood. This study aims, first, to investigate the association between negative symptoms and psychomotor slowing. Second, we want to investigate whether fine motor slowing reflects clinically observable gross motor slowing.

METHODS

In 53 stabilised adult patients with schizophrenia, negative symptoms were assessed using the Positive and Negative Syndrome Scale negative subscale (PANSS-N) with two calculated factors entering the analysis: an expressivity factor and a volitional factor. Psychomotor slowing was assessed by using a modified version of the Salpêtrière Retardation Rating Scale, the Finger Tapping Test, and a writing task measuring fine psychomotor slowing.

RESULTS

Negative symptomatology is associated with difficulties in the initiation of fine motor movements, r=.334, p<.05, whilst planning and execution are not. The volitional factor, r=-.407, p=.005, but not the expressivity factor, r=.060, p=.689, is significantly associated with psychomotor slowing. No associations between fine and clinically observable gross psychomotor functioning were found.

CONCLUSIONS

These findings indicate that higher values of negative symptomatology-more specifically the volitional deficit cluster-affect motor initiation, indicating a heterogeneity in the PANSS-N factorial structure, and that gross and fine psychomotor functioning are affected independently.

The effects of nicotine on cognition are dependent on baseline performance

Since cholinergic neurotransmission plays a major role in cognition, stimulation of the nicotinic acetylcholine receptor may be a target for cognitive enhancement. While nicotine improves performance on several cognitive domains, results of individual studies vary. A possible explanation for these findings is that the effect of nicotine administration may be dependent on baseline cognitive function, where subjects with a suboptimal cognitive performance may benefit from nicotine, while subjects who already perform optimally may show a decline in performance after nicotinic stimulation. We conducted a double-blind randomised placebo-controlled crossover trial, examining the effects of placebo, 1, and 2mg of nicotine on cognition in young (n=16, age 18-30 years) and healthy elderly (n=16, age 60-75 years) subjects. We hypothesised that the elderly would benefit more from nicotine compared to young subjects, as normal ageing is associated with decreases in cognitive function. Attention, working memory, visual memory, information-processing speed, psychomotor function, stereotypy, and emotion recognition were assessed. Compared to the young volunteers, the elderly performed significantly worse on psychomotor function and emotion recognition in the placebo condition. Nicotine had no effect in the young volunteers and decreased performance on working memory and visual memory in the elderly. Contrary to our hypothesis, the effect of nicotine was dependent on baseline performance in both the groups, with subjects with lower baseline performance benefiting from nicotine administration, while those with higher baseline performance performed worse after nicotine administration. This suggests that subjects with lower cognitive performance, irrespective of age, may benefit from nicotine.

The nicotinergic receptor as a target for cognitive enhancement in schizophrenia: barking up the wrong tree?

RATIONALE

Cognitive symptoms have increasingly been recognized as an important target in the development of future treatment strategies in schizophrenia. The nicotinergic neurotransmission system has been suggested as a potentially interesting treatment target for these cognitive deficits. However, previous research yielded conflicting results, which may be explained by several methodological limitations, such as the failure to include both a group of smoking and non-smoking schizophrenic patients, the use of only a single nicotine dose, and the inclusion of a very limited cognitive battery.

OBJECTIVES

The present study aims at investigating the cognitive effects of nicotine in schizophrenia while addressing these methodological issues.

METHODS

In a double-blind placebo-controlled randomized crossover design, cognitive effects are assessed in smoking (n =16) and non-smoking (n =16) schizophrenic patients after receiving active (1 or 2 mg) or placebo oromucosal nicotine spray.

RESULTS

A modest improving effect of nicotine on attention in the smoking but not the non-smoking group was found. No enhancing effects were found on measures of visual memory, working memory, processing speed, psychomotor speed, or social cognitive functioning in either patient group.

CONCLUSIONS

These findings suggest that the nicotinic receptor only has limited value as a cognitive treatment target in schizophrenia.

Influences of COMT and 5-HTTLPR polymorphisms on cognitive flexibility in healthy women: inhibition of prepotent responses and memory updating

Understanding genetic factors that affect monoamine neurotransmitters flux in prefrontal cortex may help to further specify the complex neurobiological processes that underlie cognitive function and dysfunction in health and illness. The current study examined the associations between the polymorphisms of dopaminergic (COMT Met158Val) and serotoninergic (5-HTTLPR) genes and the sequential pattern of responses in a motor random generation task providing well-established indexes for executive functioning in a large sample of 255 healthy women. Participants homozygous for the Met allele of the COMT polymorphism showed impaired inhibition of prepotent responses, whereas individuals homozygous for the s-allele of the 5-HTTLPR showed a restricted ability to update information in working memory. Taken together the results indicate differentiated influences of dopaminergic and serotonergic genes on important and definite executive sub-processes related to cognitive flexibility.

Differentiation between deviant trajectory planning, action planning, and reduced psychomotor speed in schizophrenia

INTRODUCTION

Abnormal psychomotor behaviour in schizophrenia might be based on separate deficits. Here we studied the relationship between trajectory planning, action planning, psychomotor speed, and indices of cognitive functioning in a large group of stabilised patients with schizophrenia.

METHOD

Sixty-one patients and 30 controls were tested. Trajectory planning was assessed in a graphic task in which sequences of single lines, gradually changing in direction, had to be drawn. Shifts to a comfortable drawing direction reflect anticipatory trajectory planning. Action planning was evaluated in a task in which figures varying in complexity and familiarity had to be copied. Psychomotor speed was measured by use of a simple line copying task. Measures of information processing speed, attention, working memory, and problem solving were derived from neuropsychological tests.

RESULTS

Patients much more often opted for the unusual bottom-to-top direction to draw the vertical lines in the drawing task. They changed the line orientation less often than the controls did. In the patient group, these trajectory planning indices did not correlate with measures of action planning, psychomotor speed, or neuropsychological test scores.

CONCLUSION

Deviant trajectory planning strongly characterises schizophrenia, and is independent from action planning deficits and reduced psychomotor speed.

A computer program for testing and analyzing random generation behavior in normal and clinical samples: the Mittenecker Pointing Test

Random sequence generation tests have proved to be a useful diagnostic tool for the identification of clinically relevant impairments of executive functions and for the study of cognitive functioning in healthy individuals. The most prevalent variety, random number generation, involves several limitations, however. In the original Mittenecker Pointing Test (MPT; Mittenecker, 1958), subjects were instructed to point successively and as randomly as possible at nine unlabeled circles irregularly arranged on a cardboard. With the computer program presented here, Mittenecker's classical test has been transferred to a contemporary format. The MPT can be applied using a standard PC keyboard and computes a series of sophisticated measures of deviations from randomness on the basis of information theory analysis. Because of its easy and well-controlled administration and reduced demands on memory and attention, the automatized MPT offers a wide range of application possibilities in normal but also in severely impaired clinical samples.