Poor Response Inhibition and Symptoms of Inattentiveness Are Core Characteristics of Lifetime Illicit Substance Use among Young Adults in the General Norwegian Population: The HUNT Study.

BACKGROUND: Impairments in neurocognitive functioning are associated with substance use behavior. Previous studies in neurocognitive predictors of substance use typically use self-report measures rather than neuropsychological performance measures and suffer from low sample sizes and use of clinical diagnostic cut offs. METHODS: Crossectional data from the HUNT4 Study (Helseundersøkelsen i Trøndelag) was used to study executive neuropsychological performance and self-reported measures of neurocognitive function associated with a history of illicit substance use in a general population sample of young adults in Norway. We performed both between group comparisons and logistic regression modeling and controlled for mental health symptomatology. RESULTS: Subjects in our cohort with a self-reported use of illicit substances had significantly higher self-reported mental health and neurocognitive symptom load. A logistic regression model with substance use as response included sex, commission errors and self-reported inattentiveness and anxiety as significant predictors. After 10-fold cross-validation this model achieved a moderate area under the receiver-operator curve of 0.63. To handle the class imbalance typically found in such population data, we also calculated balanced accuracy with a optimal model cut off of 0.234 with a sensitivity of 0.50 and specificity of 0.76 as well as precision recall-area under the curve of 0.28. CONCLUSIONS: Subtle cognitive dysfunction differentiates subjects with and without a history of illicit substance use. Neurocognitive factors outperformed the effects of depressive symptoms on substance use behavior in this cohort. We highlight the need for using adequate statistical tools for evaluating the performance of models in unbalanced datasets.

Effect of surgical parameters on the biomechanical behaviour of bicondylar total knee endoprostheses - A robot-assisted test method based on a musculoskeletal model.

The complicated interplay of total knee replacement (TKR) positioning and patient-specific soft tissue conditions still causes a considerable number of unsatisfactory outcomes. Therefore, we deployed a robot-assisted test method, in which a six-axis robot moved and loaded a bicondylar cruciate-retaining (CR)-TKR in a virtual lower extremity emulated by a musculoskeletal multibody model. This enabled us to systematically analyse the impact of the posterior cruciate ligament (PCL), tibial slope, and tibial component rotation on TKR function while considering the physical implant components and physiological-like conditions during dynamic motions. The PCL resection yielded a decrease of femoral rollback by 4.5 mm and a reduction of tibiofemoral contact force by 50 N. A reduced tibial slope led to an increase of tibiofemoral contact force by about 170 N and a decrease of femoral rollback up to 1.7 mm. Although a higher tibial slope reduced the contact force, excessive tibial slopes should be avoided to prevent joint instability. Contrary to an external rotation of the tibial component, an internal rotation clearly increased the contact force and lateral femoral rollback. Our data contribute to improved understanding the biomechanics of TKRs and show the capabilities of the robot-assisted test method based on a musculoskeletal multibody model as a preoperative planning tool.

Short-term effects of a peer co-led educational programme delivered before mental health treatment: A randomised controlled trial.

OBJECTIVE: To investigate the 1-month effects of an educational programme co-led by peers delivered before treatment on treatment preferences, self-management knowledge and motivation in comparison to usual care. METHODS: Adults referred to a community mental health centre were randomised to either a control group (n=48) or a peer co-led educational programme (intervention group, n=45). The programme consisted of an 8-hour group education session followed by an individual pretreatment planning session. The main topics of the educational programme were treatment options, patients' rights, self-management, the importance of patient activation and participation. RESULTS: At 1-month follow-up, a significantly larger proportion of the patients in the intervention group knew which type of treatment they preferred (76.7% vs. 32.5%, p<0.001). The intervention group had significantly higher self-management knowledge (p<0.001). There was no effect on treatment motivation (p=0.543). CONCLUSION: At 1-month following the delivery of a pretreatment educational programme, we found that participants' knowledge of treatment preferences and self-management had improved. PRACTICE IMPLICATIONS: Educational interventions co-led by peers can optimise the process of informing and educating outpatients, thereby helping patients to clarify their treatment preferences.

Two years of continued early treatment for recent-onset schizophrenia: a randomised controlled study.

OBJECTIVE: This random-controlled study evaluated benefits derived from continued integrated biomedical and psychosocial treatment for recent-onset schizophrenia. METHOD: Fifty cases of schizophrenia of less than 2 years duration were allocated randomly to integrated or standard treatment (ST) for 2 years. ST comprised optimal pharmacotherapy and case management, while IT also included cognitive-behavioural family treatment, that incorporated skills training, cognitive-behavioural strategies for residual psychotic and non-psychotic problems and home-based crisis management. Psychopathology, functioning, hospitalisation and suicidal behaviours were assessed two monthly and a composite index, reflecting overall clinical outcome was derived. RESULTS: IC proved superior to ST in reducing negative symptoms, minor psychotic episodes and in stabilising positive symptoms, but did not reduce hospital admissions or major psychotic recurrences. The composite index showed that significantly more IC patients (53%) had excellent 2-year outcomes than ST (25%). CONCLUSION: Evidence-based treatment achieves greater clinical benefits than pharmacotherapy and case management alone for recent-onset schizophrenia.

Neuropsychological impairments in patients with schizophrenia: stability and prediction of outcome.

OBJECTIVE: To assess neuropsychological impairments among fairly young schizophrenic patients over time, and relations between impairment and symptoms, drug type and dose. METHOD: Clinical and neuropsychological data for 29 schizophrenic patients have been published earlier. Twenty of these patients were retested after 3 years using the same methods. RESULTS: The patients displayed stable impairments in most neuropsychological tests. Vocabulary and focused attention improved over time, whereas response slowness became more pronounced. Symptoms varied considerably over time. A specific pattern of neuropsychological impairments, but not measures of psychopathology, predicted clinical outcome. Patients were unable to judge their test performance. CONCLUSION: A few years after the first episode, our patients displayed a specific pattern of neuropsychological impairment, which predicted clinical outcome. One aspect of the impairment appears to be failure at self-monitoring.

Schizophrenia--progressive and massive decline in response readiness by episodes.

OBJECTIVE: To relate the pattern of neuropsychological impairments among schizophrenic patients to case history data and disease characteristics in a cross-sectional study of unselected patients, and to integrate these data with two previous longitudinal studies of neuropsychological impairments among schizophrenic patients. METHOD: One hundred consecutive schizophrenic patients were studied with respect to clinical case history and current symptoms, medication and neuropsychological impairment using a comprehensive computerized test battery. RESULTS: The most salient finding was a marked slowing of response readiness, linearly related to the number of previous acute episodes. The resulting deficit was far beyond what has been obtained in any other group of subjects (average -6 SD for >five episode patients). The impairments in many of the other neuropsychological parameters could to some extent be explained with reference to response slowing, with one exception--verbal short-term memory. Adjustment for important confounding factors (age, duration of illness, medication) did not change the strong negative association between response readiness and number of previous episodes. CONCLUSION: These findings, together with findings of our two previous longitudinal studies and a recent replication, prompted us to suggest that each acute schizophrenic episode inflicts damage to a set of hypothetical structures, cognitive pattern generators. We assume that these structures translate intentions to logistic programs. When damaged, delays are introduced into executive functions and corollary discharge processes will run out of phase with intentions. This model implicates new ways of looking at the generative mechanisms of the illness, and on treatment strategies.

Smooth pursuit eye movements and neuropsychological impairments in schizophrenia.

Smooth pursuit eye movements (SPEM) and neuropsychological performance were examined in a sample of 29 drug-treated schizophrenic patients and 22 healthy controls. Patients had impairment in SPEM as well as in a wide range of neuropsychological tests (Wechsler Adult Intelligence Scale, Wisconsin Card Sorting Test. Finger Tapping, Reaction time, Selective attention, Trail-Making and Simultaneous Capacity). Performance indices were more affected than strategy-executive indices. Drug type (clozapine vs typical) and dose (chlorpromazine units) were not related to neuropsychological impairment among the patients. Indices from the whole range of tests accurately predicted a subjects' group identity (patient vs control). Impaired SPEM was predicted more accurately by tests assessing frontal functions. Seven patients, all men, had only marginal neuropsychological impairments.

Aversive and compensatory classical conditioning with diazepam as conditional stimulus.

The purpose of the first experiment was to investigate whether diazepam could acquire anxiogenic properties by signalling an aversive event. Rats were trained in an operant chamber in the pentylenetetrazol (PTZ) model of anxiety. Thereafter the animals were divided into groups that received classical diazepam conditioning (Group 1), and conditioning of diazepam + tone (Group 2). In the test phase diazepam was injected prior to placement in the operant chamber. Group 2 selected the PTZ-appropriate lever more often than the other groups, indicating that the tone induced anxiety, and diazepam did not. Tones and shock may therefore be more easily associated than diazepam and shock. The second experiment investigated this. Rats were trained the same way as in the first experiment. Thereafter the experimental group received injections of a small dose of diazepam prior to a second injection of a large dose of diazepam. The hypothesis was that a compensatory anxiogenic conditional response to diazepam's anxiolytic effect should be elicited by the small dose. There were no differences between the groups in lever selection, indicating that a compensatory anxiogenic response was not elicited.