Low IQ scores in schizophrenia: primary or secondary deficit?

BACKGROUND: Schizophrenia is consistently associated with lower IQ compared to the IQ of control groups, or estimated premorbid IQ. It is not likely that the IQ scores deteriorate during the prodromal phase or first psychotic episode; they are already present before the onset of the prodromal phase and have been detected in childhood. METHODS: We investigated cognitive functioning and IQ levels in a group of 36 patients with schizophrenia or other psychotic disorders. RESULTS: The IQ scores in our sample were lower than average. The IQ showed a relation with attention, memory, speed of information processing and some aspects of executive functioning. However, when IQ scores were corrected for processing speed, they were no longer below average. CONCLUSIONS: These findings are important in considering the value of intelligence levels in schizophrenia. IQ scores should be judged in combination with cognitive functioning and school career to assess a patients capabilities in society. Cognitive functions and other variables might have a considerable influence on IQ scores. This rises the question of whether the low IQ scores are a primary or secondary deficit. Schizophrenia patients may have normal IQs, but could be less capable of making an IQ-test.

Construct validity of concepts of attention in healthy controls and patients with CHI.

The present study aimed to examine the construct validity of three aspects of attention, namely focused, divided, and supervisory control of attention. Factor-analytic techniques were applied to scores of healthy subjects on a series of neuropsychological tests tapping these aspects of attention. The two components found did not match the hypothesized aspects and were labeled as Memory-driven Action and Stimulus-driven Reaction. The second question was whether the same components could be found in a group of patients with CHI. The pattern of attentional functions found in healthy subjects had changed qualitatively in patients with CHI. A possible explanation for this result in terms of a shift from automatic to controlled processing is discussed.

[Cognitive impairments among older drivers: medical examination and driving test]. / Autorijden bij ouderen met cognitieve functiestoornissen: medische keuring en rijtest.

The aim of this study was to gain insight in the prevalence of cognitive impairments among active older drivers and in driving performance of cognitively impaired ones. The study was implemented in the existing Dutch relicensing procedure for older drivers and consisted of three evaluation moments: a medical screening (for all subjects), a neuropsychological assessment and a test-drive (for candidates with cognitive impairments). In total, 2992 drivers were medically evaluated. In 4% of cases indications for impaired cognitive functioning were observed that could be evaluated and confirmed with neuropsychological tests. Eighty subjects performed an on-road test. Of these subjects, 57% were allowed to renew their driver's license, while in the remaining 43% no new licenses or restricted licenses were issued. During the test-drive, slow reactions and attention deficits were the most important causes for impaired fitness to drive.

Acute behavioural disturbances related to imaging studies and outcome in mild-to-moderate head injury.

The frequency of behavioural disturbances early after injury in relation to outcome was prospectively investigated in a series of 67 patients with mild-to-moderate head injury (as defined by GCS on admission). In more than half of the patients, behavioural disturbances were observed. Restlessness occurred in 40% of patients, whereas agitation was seen in 19% of patients. In all patients, restlessness and agitation disappeared before resolution of PTA. In multiple regression analysis, restlessness and PTA were found to be separate factors in predicting outcome. On imaging studies, twice as many lesions were seen in patients with restlessness and agitation (81% compared to 39%), mainly localized in the frontotemporal region. In two thirds of patients with early behavioural disturbances, residual emotional and cognitive impairments were seen 1 year after injury. This study suggests that behavioural disturbances in the early phase after injury are related to frontotemporal lesions and lends support for the view of the existence of a separate profile of patient behaviour in mild-to-moderate head injury.

Fitness to drive in older drivers with cognitive impairment.

This paper is a literature review on assessment of fitness to drive in older drivers with cognitive impairment. Early studies on dementia and driving generally failed to distinguish between safe and unsafe drivers on the basis of cognitive test performance. Predictive studies demonstrated that cognitively impaired persons as a group perform significantly worse than controls on both neuropsychological and driving measures. A high prevalence of cognitive impairment was found in groups of older drivers involved in traffic accidents and crashes. However, a large range in neuropsychological test scores has been found. Low to moderate correlations could be established between neuropsychological test results and on-road driving performance, making it difficult to discriminate between cognitively impaired subjects who are fit or unfit to drive. The review concludes with a discussion of methodological difficulties in the field of dementia and driving, including participant selection, the choice of neuropsychological tests, and the operationalization of driving performance.

Executive functioning, attention and frontal lesions in patients with chronic CHI.

To study the presence and nature of dysexecutive problems after CHI, a series of unstructured tasks tapping executive functioning were selected. These were administered to a group of 51 participants with CHI in the chronic stage (i.e. several years post-injury) and to 45 healthy controls. In addition, well-known structured tests of attention and planning were administered. Of the executive tasks, only the Executive Route Finding task showed a significant difference between both groups. A multivariate analysis on the attention tests showed a significant difference between groups, indicating that patients in the chronic stage still process information slower than controls. Within the patient group, patients with and without frontal focal lesions were also compared on executive and attention tests. No differences were found with respect to the latter. However, patients with frontal lesions performed worse on a measure of the Executive Route Finding task. It is concluded that patients with CHI, especially when they have frontal damage, have to rely more heavily on externally provided cues, but this dysexecutive problem can only be demonstrated in tasks that resemble daily life tasks by providing very little structure.

Unilateral pallidotomy in PD: a controlled study of cognitive and behavioral effects. The Netherlands Pallidotomy Study (NEPAS) group.

OBJECTIVE: To investigate whether unilateral pallidotomy affects cognitive and behavioral functioning. METHODS: At baseline and after 6 months we assessed neuropsychological functioning in 35 patients with advanced PD. After baseline examination, patients were randomized to pallidotomy within 1 month (6 left-sided, 13 right-sided) or to pallidotomy after follow-up assessment 6 months later (n = 16; control group). We performed neuropsychological tests of language, visuospatial function, memory, attention, and executive functions. Self ratings and proxy ratings of memory problems and dysexecutive symptoms were also collected. RESULTS: No significant differences over time were found between pallidotomy and control groups, with the exception of a decrease of verbal fluency in the left-sided pallidotomy group. CONCLUSIONS: Unilateral pallidotomy is relatively safe with respect to cognition and behavior. Left-sided pallidotomy may lead to minor deterioration in verbal fluency. The sample size of this study is too small, however, to rule out the possibility of infrequent but clinically important side effects.

Computed tomography and magnetic resonance imaging in mild to moderate head injury: early and late imaging related to outcome.

Serial magnetic resonance imaging (MRI) and computed tomographic (CT) studies were performed in mild to moderate head injury to evaluate whether early and late imaging have additional value in predicting outcome in this category of patients. During 1-year follow-up of a series of 67 patients, a CT scan on admission was performed together with MRI studies within 1 to 3 months and 6 to 12 months after injury. With CT, intracranial lesions were seen in 62% of patients compared with 44% with early and 19% with late MRI, located predominantly in the frontal and temporal regions. More than half of the lesions revealed with CT resulted in focal atrophy on MRI. Outcome was found to be worse in patients with edema and lesions on CT. Likewise, abnormalities detected with MRI were associated with poor outcome scores. In multiple regression analysis, only lesions in the frontal regions detected with early MRI were found to be predictive of outcome. With late MRI, only focal atrophy in the frontotemporal regions was found to be predictive of outcome. The findings in this study suggests that MRI studies may be valuable for predicting long-term outcome in patients with mild to moderate HI.

Regional specific changes of cerebral metabolism in systemic lupus erythematosus identified by positron emission tomography.

In order to test the hypothesis whether the pathogenesis of cerebral systemic lupus erythematosus (SLE) may include an immune-mediated deficit in specific vulnerable brain regions, the regional cerebral metabolism in 9 patients with diffuse as well as focal cerebral symptoms was compared with that of 10 age-matched control subjects. The cerebral distribution of 2-[18F]fluoro-2-deoxy-D-glucose (FDG) uptake was measured by means of positron emission tomography. Subsequently performed statistical parametric mapping showed (i) a relative increase in metabolism in the striatum and (ii) regional decreases in the premotor cortex as a common feature in the patient group. Region of interest measurements of absolute FDG uptake confirmed these findings. The increased striatal activity may support the presence of a direct immune response against neuronal tissue in SLE, similar to the cross-reaction against inhibitory components in striatal tissue provoked by streptococcal antigens.

One year outcome in mild to moderate head injury: the predictive value of acute injury characteristics related to complaints and return to work.

OBJECTIVES: To determine the prognostic value of characteristics of acute injury and duration of post-traumatic amnesia (PTA) for long term outcome in patients with mild to moderate head injury in terms of complaints and return to work. METHODS: Patients with a Glasgow coma score (GCS) on admission of 9-14 were included. Post-traumatic amnesia was assessed prospectively. Follow up was performed at 1, 3, 6, and 12 months after injury. Outcome was determined by the Glasgow outcome scale (GOS) 1 year after injury and compared with a more detailed outcome scale (DOS) comprising cognitive and neurobehavioural aspects. RESULTS: Sixty seven patients were included, mean age 33.2 (SD 14.7) years and mean PTA 7.8 (SD 7.3) days. One year after injury, 73% of patients had resumed previous work although most (84%) still reported complaints. The most frequent complaints were headache (32%), irritability (34%), forgetfulness and poor concentration (42%), and fatigue (45%). According to the GOS good recovery (82%) or moderate disability (18%) was seen. Application of the DOS showed more cognitive (40%) and behavioural problems (48%), interfering with return to work. Correlation between the GOS and DOS was high (r=0.87, p<0.01). Outcome correlated with duration of PTA (r=-0.46) but not significantly with GCS on admission (r=0.19). In multiple regression analysis, PTA and the number of complaints 3 months after injury explained 49% of variance on outcome as assessed with the GOS, and 60% with the DOS. CONCLUSIONS: In mild to moderate head injury outcome is determined by duration of PTA and not by GCS on admission. Most patients return to work despite having complaints. The application of a more detailed outcome scale will increase accuracy in predicting outcome in this category of patients with head injury.

Lightning stroke and neuropsychological impairment: cases and questions.

OBJECTIVE: To objectify neuropsychological impairments in survivors of lightning stroke with lasting complaints about poor concentration and inability to divide their attention. DESIGN: A series of six cases of lightning stroke were studied. All patients had lost consciousness and reported amnesia of varying length. Assessment took place between one and four years after injury, ensuring that their neurological state had stabilised. They were tested with a neuropsychological battery with an emphasis on attention and memory. Personality and emotional reaction to the accident were assessed with questionnaires and a lightning fear scale. Complaints were recorded by means of a trauma complaints list including 10 questions on symptoms of the post-traumatic stress disorder. RESULTS: Patients reported fatigue and lack of energy as their main complaints. In addition, poor concentration, irritability, and emotional lability were mentioned often. Neuropsychological tests disclosed mild impairments in memory, attention, and visual reaction times. Two patients could be classified as depressed, and one of these also showed convincing signs of the post-traumatic stress disorder. CONCLUSION: As the lasting complaints and impairments could not be explained, for all six cases, as resulting from head injury concomitant with lightning stroke, cerebral hypoxia or a post-traumatic stress syndrome, it is concluded that lightning stroke can result in subtle cognitive impairments. It is speculated that most complaints of these survivors are caused by a vegetative dysregulation, a disorder that has often been noted in the literature on the effects of electrical injury to the nervous system. Such a dysregulation might cause both the main complaint of fatigue and the mild cognitive impairments identified with the present test battery.

Deficits of attention after closed-head injury: slowness only?

The performance of a group of 60 severely closed-head-injured patients in the subacute stage of recovery on a series of tests addressing focused, divided, and sustained attention, and supervisory attentional control was compared to the performance of a matched group of 60 healthy controls. Patients performed significantly worse on each test with time pressure (those addressing focused and divided attention), indicating basic slowness of information processing, and on the self-paced tasks for supervisory attentional control. No indication was found of a sustained attention deficit. In a subsequent analysis the influence of the demonstrated slowness of information processing and other possibly confounding cognitive factors was controlled for by means of covariance analyses. This resulted in a disappearance of group differences on tests for focused and divided attention. The only difference that remained concerned a test for supervisory attentional control.

Brain activity related to serial cognitive performance resembles circuitry of higher order motor control.

Differences between two states of cerebral activation were studied in eight subjects by positron emission tomography (PET) of regional cerebral blood flow (rCBF) and subsequent statistical parameter mapping. Subjects had to respond to a row of numbers presented on tape. In one condition they had to repeat each number. In the other condition the last heard number had to be added to the number presented before. Cerebral activity specifically related to the serial addition task was distributed over supplementary motor area (SMA), left premotor cortex and superior dorsal parietal cortex bilaterally, without significant involvement of prefrontal cortex. This indicated circuitry related to mental performance characterised by a fixed strategy of executing serial manipulation of numbers within "internal space". The main aim of this communication is to discuss the similarity between circuitry underlying higher order motor control and pure cognitive performance.

The fronto-temporal component in mild and moderately severe head injury.

The history of the identification of the so-called (fronto-)temporal lobe contusion is reviewed. Treatment of minor head injuries actually starts with the right diagnosis. Injuries of the temporal lobe, characterized by a comparatively long period of post-traumatic amnesia should be distinguished from minor head injuries (cerebral concussion). Treatment of minor head injuries should include good information and explanation of the medical aspects of minor head injuries to prevent the so called post-concussional syndrome, with long lasting sequelae. Changes of neurotransmitter metabolism in various kinds of head injuries have been known for many years. Treatment with precursors of neurotransmitters (particularly physostigmine and L-DOPA) can be useful in unconsciousness and amnestic syndromes.

Cobalt-55 positron emission tomography in traumatic brain injury: a pilot study.

Traumatic brain injury is usually assessed with the Glasgow coma scale (GCS), CT, or MRI. After such injury, the injured brain tissue is characterised by calcium mediated neuronal damage and inflammation. Positron emission tomography with the isotope cobalt-55 (Co-PET) as a calcium tracer enables imaging of affected tissue in traumatic brain injury. The aim was to determine whether additional information can be gained by Co-PET in the diagnosis of moderate traumatic brain injury and to assess any prognostic value of Co-PET. Five patients with recent moderately severe traumatic brain injury were studied. CT was performed on the day of admission, EEG within one week, and MRI and Co-PET within four weeks of injury. Clinical assessment included neurological examination, GCS, neuropsychological testing, and Glasgow outcome scale (GOS) after one year. Co-PET showed focal uptake that extended beyond the morphological abnormalities shown by MRI and CT, in brain regions that were actually diagnosed with EEG. Thus Co-PET is potentially useful for diagnostic localisation of both structural and functional abnormalities in moderate traumatic brain injury.

Divided attention 5 to 10 years after severe closed head injury.

The ability to divide attention of persons who had sustained a severe Closed Head Injury 5 to 10 years before (chronic CHI patients), was examined in a dual-task experiment administered to 15 CHI patients and 34 control subjects. Both the patient group and the control group consisted of active licenced drivers at the time of the investigation. One task was a compensatory tracking task requiring lane tracking, a basic skill or car driving. The other task was a self-paced visual choice reaction time task. Single-task difficulty was individually adjusted by adaptive task procedures (on both tasks CHI patients reached significantly lower performance levels in single task conditions). With individual differences in single-task performance thus controlled, the ability to divide attention was found to be approximately equal in the chronic CHI patients and the control group. A surprising finding in this light, however, was the significant positive correlation between severity of injury (PTA duration) and divided attention costs in the patient group.

Fitness to drive a car after recovery from severe head injury.

Driving skills in relation to residual psychologic impairments were studied in a sample of patients who had survived severe head injuries several years earlier. Daytime driving was studied in an instrumented car that recorded lateral position control on a highway track and during rides in the subjects' own cars with a professional observer. In comparison with a control group matched by age and driving experience, the patients performed worse on both driving tasks. In addition, the patient group showed clear impairments on a neuropsychologic test battery, despite the long intervals since their injuries. However, the only relationships found between test performance and driving involved visuomotor ability and lateral position control. No relationship was found between neurologic status and driving skill. The results are discussed in terms of patients' compensatory potential.

Acquired brain damage and driving: a review.

Five issues in evaluating driving ability after brain damage were addressed through a review of the literature. Some preliminary conclusions were reached: (1) about half of all subjects studied still hold a valid driver's license; (2) brain-damaged drivers could not, in general, be seen as risky drivers, although some individuals show decreased driving skill and risky behavior in traffic; and (3) statistics show no increase in traffic violations or accidents in groups of neurologic patients with acquired brain lesions or diseases. Frequently noted problems of brain-damaged drivers include poor judgment of traffic situations, impulsivity, and visuospatial impairments. Traditional psychologic tests have insufficient predictive value regarding fitness to drive. It is suggested that new techniques be developed to enable more valid statements about the skills needed for safe traffic participation. These assessment techniques should emphasize the higher cognitive levels in driving, ie, the tactical and strategic levels. At the moment, driver training programs in rehabilitation focus mainly on the operational level, with emphasis on handling the car, use of controls and mirrors, and technical adaptation of the vehicle.

Cognitive impairment in patients with multiple sclerosis and mild physical disability.

Forty mildly disabled and clinically stable patients with multiple sclerosis (MS), representative of the corresponding population in Northern Holland, with disability Status Scale scores evenly distributed within the 1 to 4 range, were compared with 40 age-, sex-, and education-matched normal controls on a battery of neuropsychological tests. Apart from impairments in perceptual-motor functioning, generally mild deficiencies in intelligence and, specifically, in memory were displayed in the MS group. Attentional processes appeared uncompromised. Increasing fatigue during testing could not account for poor performance. The memory deficits could be attributed to poor initial learning, although there was also evidence suggesting that accelerated forgetting of what had been learned may appear with the progression of MS. Seven patients (17.5%), as compared with none of the controls, were classified by blind clinical judgement of test performance as definitely impaired.