Personal Disturbance Scale: Factor Structure Confirmed in a Large Nonclinical Sample

The two-component structure of anxiety and depression items of the short form Personal Disturbance Scale, reported in an earlier clinical study of 480 adult psychiatric patients, was substantially replicated in a large nonclinical sample of 758 adults.

Survivin as a therapeutic target in Sonic hedgehog-driven medulloblastoma

Medulloblastoma (MB) is a highly malignant brain tumor that occurs primarily in children. Although surgery, radiation and high-dose chemotherapy have led to increased survival, many MB patients still die from their disease, and patients who survive suffer severe long-term side effects as a consequence of treatment. Thus, more effective and less toxic therapies for MB are critically important. Development of such therapies depends in part on identification of genes that are necessary for growth and survival of tumor cells. Survivin is an inhibitor of apoptosis protein that regulates cell cycle progression and resistance to apoptosis, is frequently expressed in human MB and when expressed at high levels predicts poor clinical outcome. Therefore, we hypothesized that Survivin may have a critical role in growth and survival of MB cells and that targeting it may enhance MB therapy. Here we show that Survivin is overexpressed in tumors from patched (Ptch) mutant mice, a model of Sonic hedgehog (SHH)-driven MB. Genetic deletion of survivin in Ptch mutant tumor cells significantly inhibits proliferation and causes cell cycle arrest. Treatment with small-molecule antagonists of Survivin impairs proliferation and survival of both murine and human MB cells. Finally, Survivin antagonists impede growth of MB cells in vivo. These studies highlight the importance of Survivin in SHH-driven MB, and suggest that it may represent a novel therapeutic target in patients with this disease.

Incidental MRI findings of acute gadolinium hypersensitivity

A 13-year-old girl with a remote history of juvenile pilocytic astrocytoma developed acute onset flushing, tachycardia and shortness of breath immediately following administration of gadopentetate dimeglumine during routine brain MRI that subsided following intravenous diphenhydramine. A retrospective review of the MRI results revealed multiple areas of contrast enhancement of the face, consistent with observed urticaria. The patient received pretreatment medications prior to subsequent gadolinium injections without incident. Gadolinium allergy is extremely rare and has been reported in less than 0.1% of injections. However, in patients who undergo anesthesia for MRI studies, similar subtle extracranial MRI findings should alert the neuroradiologist to possible gadolinium allergy that may warrant premedication prior to future injections.

A model of personality change after traumatic brain injury and the development of the Brain Injury Personality Scales

OBJECTIVE

The aims of this study were to develop models of personality change after traumatic brain injury (TBI) based on information provided by the TBI survivor and a significant other (SO), and to compare the models generated from the two different sources of information.

METHODS

Individuals with and without TBI and an SO were interviewed separately about their current personality. The SOs were also interviewed about the personality of the TBI survivor before the injury. A subset of TBI survivors and their SOs were interviewed twice to assess test-retest reliability. Items which were not associated with personality change after TBI, which could not be measured reliably or which did not contribute to the model, were excluded.

RESULTS

Of the 123 original items, 29 items from the interview with the survivor and 31 items from the interview with the SO were retained to form the Brain Injury Personality Scales. Separate factor analyses of ratings from each interview (survivor and SO) resulted in seven first order factors. The second order factor analyses for each interview resulted in four factors. Concordance between the information obtained from the two interviews was low.

CONCLUSIONS

The information obtained from the interviews with the TBI survivors and the SOs produced two models with a similar structure: three superordinate factors of personality items (affective regulation, behavioural regulation and engagement) and one superordinate factor of items relevant to mental state (restlessness and range of thought). Despite the similarity in structure, the content of the information obtained from the two interviews was different.

CNS germ cell tumor (CNSGCT) of childhood: presentation and delayed diagnosis

OBJECTIVE

To describe the relationship between symptomatology and time to diagnosis of an institutional series of patients with CNS germ cell tumor (CNSGCT) over a 16-year period.

METHODS

Thirty consecutive patients newly diagnosed with CNSGCT (mean age 10.9 years; range 6 to 17 years; 70% boys) were evaluated at our institution between 1990 and 2006.

RESULTS

Duration of symptoms prior to diagnosis ranged from 5 days to 3 years (mean 8.4 months). Tumor location included pineal (14), suprasellar (8), pineal/suprasellar (3), pineal/thalamic (4), and basal ganglionic/thalamic (3). Five patients had disseminated disease at the time of diagnosis. Features including headache, nausea, vomiting, and visual changes led to earlier diagnosis. Symptoms including movement disorders, enuresis, anorexia, and psychiatric complaints delayed diagnosis in 9 of 30 patients, diagnosed 7 months to 3 years (mean 22.3 months) from symptom onset. In 7 of 9 patients with delayed diagnosis, enuresis was present. Seventeen of 30 patients had signs of endocrine dysfunction at presentation that included diabetes insipidus (4), hypothyroidism (8), and growth hormone deficiency (4). Ophthalmologic findings of decreased visual acuity, visual field deficits, or ocular abnormalities were present in 13 patients. Duration of symptoms did not correlate with tumor subtype or event-free survival. In three patients with basal ganglionic/temporal lobe, thalamic, or pineal/suprasellar signal abnormalities on MRI, neuroradiographic diagnosis was difficult.

CONCLUSIONS

Diagnosis of CNS germ cell tumor is often delayed, and presentation may include movement disorders or mimic psychiatric disease. MRI interpretation can be challenging and may require serum/CSF markers and biopsy for diagnosis.

Psychometric properties of the BASIS-24© (Behaviour and Symptom Identification Scale-Revised) Mental Health Outcome Measure

Objective. Outcome measurement in mental health services is an area of considerable clinical interest and policy priority. This study sought to assess the Behaviour and Symptom Identification Scale-24 (BASIS-24©), a brief, patient self-reported measure of psychopathology and functioning, in a UK sample, including establishing population norms for comparative purposes. Methods. Participants were 588 adults recruited from psychiatric inpatient, outpatient and primary care settings; and 630 adults randomly sampled from primary care lists who completed the BASIS-24©, and the Brief Symptom Inventory (BSI) at two time points. Results. BASIS-24© demonstrated adequate reliability (coefficient α values for combined clinical sample across subscales ranged from 0.75 to 0.91), validity and responsiveness to change (effect size for change of the BASIS-24© was 0.56 compared with 0.48 for BSI Global Severity Index). Population norms were established for the general population and adult in-patients (at in-take). The scale proved straightforward to complete across clinical settings. Variable rates of questionnaire distribution across clinical settings highlighted the ongoing challenge of incorporating outcome measures in clinical settings. Conclusion. BASIS-24© is a brief, easily administered, self-complete measure of mental well-being and functioning that adequately meets the requirements of reliability, validity and responsiveness to change required of an outcome measure.

Bone loss at hip resurfacing: A comparison with total hip arthroplasty

Resurfacing arthroplasty of the hip has been advocated as a bone-conserving procedure although concerns have been raised as to whether this is truly the case. We therefore compared bone loss during hip resurfacing with bone loss at total hip arthroplasty under controlled conditions using dry pelvic and femoral Sawbones (DePuy, Leeds, UK). Ten sets of femoral and pelvic Sawbones were included in the study. Five sets were prepared for implantation of a hybrid total hip arthroplasty and five sets were prepared for insertion of hip resurfacing components. The Sawbones were weighed before and after preparation and the amount of dry bone loss was determined. During preparation of the femur for a resurfacing arthroplasty we resected 51.4% less Sawbone than for a total hip arthroplasty (mean 12.3g vs 25.3g, p<0.001). More bone (311.1%) was removed, however, during acetabular preparation for a resurfacing arthroplasty than for a total hip arthroplasty (mean 5.6g vs 1.8g, p<0.001). The total amount of Sawbone removed was 33.9% less for a resurfacing arthroplasty compared with a total hip arthroplasty (mean 17.9g vs 27.1g, p=0.001). We conclude that although reduced resection of femoral bone may be an advantage of hip resurfacing arthroplasty, the increased amount of bone that is removed from the acetabulum may prove problematic should patients require future revision surgery. (Hip International 2005; 15: 195-8).

COMPRESSION OF THE SCIATIC NERVE BY WEAR DEBRIS FOLLOWING TOTAL HIP REPLACEMENT: A REPORT OF THREE CASES

Pain in the distribution of the sciatic nerve is common in the elderly. In the presence of a long-standing joint replacement, consideration should be given as to whether compression might be due to an extraspinal cause. We present three women, in whom a mass of wear debris from a previous total hip replacement caused compression of the sciatic nerve posterior to the hip. The symptoms were relieved immediately following operation.

Differential deficits in expression recognition in gene-carriers and patients with Huntington's disease

Previous studies in symptomatic patients and asymptomatic gene-carriers of Huntington's disease (HD) reported a differential deficit in the recognition of facial expressions of disgust. This impairment may point to involvement of the basal ganglia in the recognition of disgust. In this study, we compared the performance of 20 patients with symptoms of HD, 20 gene-carriers of HD and 20 healthy controls on two tests of facial expressions in order to further investigate the role of the basal ganglia in disgust recognition. Recognition of fear, rather than disgust, was most severely impaired in the patients, who were also impaired at recognising expressions of anger, disgust and sadness. Direct testing for a differential deficit in disgust at the group level (and at the level of individual HD cases) revealed that the patients were in fact significantly more impaired on the other negative expressions than on disgust. The gene-carriers were not impaired on any expression, although there was a trend for the gene-carriers to be poorer at recognising fearful faces than the controls. We argue that the expression recognition performance of the patients and gene-carriers simply reflects differences in task difficulty, rather than dysfunction of any mechanisms dedicated to specific emotions. In contrast to previous studies in patients or gene-carriers of HD, our findings provide no evidence for a role of the basal ganglia in the recognition of disgust and cast doubt on whether results from HD patients and gene-carriers can be used in support of a double dissociation between recognition of disgust and fear.

Investigation of the single case in neuropsychology: confidence limits on the abnormality of test scores and test score differences

Neuropsychologists often need to estimate the abnormality of an individual patient's test score, or test score discrepancies, when the normative or control sample against which the patient is compared is modest in size. Crawford and Howell [The Clinical Neuropsychologist 12 (1998) 482] and Crawford et al. [Journal of Clinical and Experimental Neuropsychology 20 (1998) 898] presented methods for obtaining point estimates of the abnormality of test scores and test score discrepancies in this situation. In the present study, we extend this work by developing methods of setting confidence limits on the estimates of abnormality. Although these limits can be used with data from normative or control samples of any size, they will be most useful when the sample sizes are modest. We also develop a method for obtaining point estimates and confidence limits on the abnormality of a discrepancy between a patient's mean score on k-tests and a test entering into that mean. Computer programs that implement the formulae for the confidence limits (and point estimates) are described and made available.

Performance on tests of frontal lobe function reflect general intellectual ability

Recent studies have indicated that performance on tests of frontal lobe function are highly associated with general intellectual ability (g). Some authors have even claimed that the available evidence does not support a more specific account of frontal lobe function than to provide a general intellectual function for the performance of goal directed tasks. We examined the relationship between performance on the WAIS-R (as a measure of g) and performance on standard tests of frontal lobe function in 123 healthy individuals. Our results demonstrate that in healthy individuals (i) performance on the most popular tests of frontal lobe function shares significant variance, and (ii) a large proportion of that shared variance is highly associated with performance on the Wechsler Adult Intelligence Scales-Revised (WAIS-R), so that the tests are similar to the extent that they measure g. Performance on the Modified Card Sorting Test (MCST), however, is not related to g. The results support the claim that many tests of frontal lobe function measure primarily a non-specific intellectual function but also indicate that some tests, like the MCST, may be assessing more specific cognitive operations.

The homophone meaning generation test: psychometric properties and a method for estimating premorbid performance

The Homophone Meaning Generation Test (HMGT; Warrington, 2000) is a new measure of verbal fluency that has been demonstrated to be sensitive to the presence of anterior lesions. In the present study we used the HMGT healthy standardization sample (N = 170) and demonstrate that scores on the HMGT do not differ significantly from a normal distribution and that the test has adequate reliability (alpha = .82). A table for obtaining confidence limits on an individual's score is presented. A regression equation for the estimation of premorbid HMGT performance was constructed using the National Adult Reading Test as the predictor variable. In a sample of 36 cases with anterior lesions estimated premorbid scores were significantly higher than obtained scores (p < .001). Premorbid ability acted to suppress group differences on the HMGT; the partial correlation between neurological status (healthy vs. anterior lesion) and HMGT performance controlling for premorbid ability (.53) was significantly higher than the raw correlation (.44). In addition, hierarchical discriminant function analysis demonstrated that the inclusion of premorbid ability improved classification over that achieved by HMGT scores alone. These results support both the underlying rationale and the clinical utility of controlling for premorbid performance when interpreting verbal fluency scores.

Normative data for the HADS from a large non-clinical sample

OBJECTIVES

To provide normative data for the Hospital Anxiety Depression Scale (HADS).

DESIGN

Repeated measures and correlational.

METHODS

The HADS was administered to a non-clinical sample, broadly representative of the general adult UK population (N = 1792) in terms of the distributions of age, gender and occupational status. Correlational analysis was used to determine the influence of demographic variables on HADS scores.

RESULTS

Demographic variables had only very modest influences on HADS scores. The reliability of the HADS is acceptable; the Anxiety and Depression scales are moderately correlated (.53). Tables to convert raw scores to percentiles are presented for females and males.

CONCLUSIONS

The present normative data allow clinicians to assess the rarity of a given HADS score, and thus provide a useful supplement to existing cut-off scores.

Problems in using health survey questionnaires in older patients with physical disabilities. The reliability and validity of the SF-36 and the effect of cognitive impairment

Reliability and validity of the SF-36 Health Survey Questionnaire was assessed in older rehabilitation patients, comparing cognitively impaired with cognitively normal subjects. The SF-36 was administered by face-to-face interview to 314 patients (58-93 years) in the day hospital and rehabilitation wards of a department of medicine for the elderly. Reliability was measured using Cronbach's alpha (for internal consistency) on the main sample and intraclass correlation coefficients on a test-retest sample; correlations with functional independence measure (FIM) were examined to assess validity. In 203 cognitively normal patients (Mini-Mental State Examination > or =24), Cronbach's alpha scores on the eight dimensions of the SF-36 ranged from 0.545 (social function) to 0.933 (bodily pain). The range for the 111 cognitively impaired patients was 0.413-0.861. Cronbach's alpha values were significantly higher (i.e. reliability was better) in the cognitively normal group for bodily pain (P = 0.003), mental health (P = 0.03) and role emotional (P = 0.04). In test-retest studies on a further 67 patients, an intraclass correlation coefficient of 0.7 was attained for five out of eight dimensions in cognitively normal patients, and four out of eight dimensions in the cognitively impaired. Only the physical function dimension in the cognitively normal group attained the criterion level (r > 0.4) for construct validity when correlated with the FIM. In this group of older physically disabled patients, levels of reliability and validity previously reported for the SF-36 in younger subjects were not attained, even on face-to-face testing. Patients with coexistent cognitive impairment performed worse than those who were cognitively normal.

Neuropsychologic correlates of brain white matter lesions depicted on MR images: 1921 Aberdeen Birth Cohort

PURPOSE

To examine relationships between brain white matter hyperintensities depicted at magnetic resonance (MR) imaging and performance on neuropsychologic tests in community-dwelling elderly adults.

MATERIALS AND METHODS

The 1921 Aberdeen Birth Cohort is a subsample of survivors of the Scottish Mental Survey of 1932 whose mental ability was tested at 11 years of age. Ninety-five of these subjects agreed to undergo brain MR imaging, an examination of general health, and a neuropsychologic evaluation. White matter hyperintensities detected at T2-weighted MR imaging were rated by using a semiquantitative method yielding two continuous variables: white matter lesions and periventricular lesions. Cognitive ability, including crystallized and fluid intelligence domains, was assessed with standard neuropsychologic tests.

RESULTS

Rating scores of white matter lesions were normally distributed (on a devised scale) with means of 1.14 for white matter lesions and 1.28 for periventricular lesions. Intra- and interobserver reliability coefficients for scores were high, generally above 0.7. There were significant correlations of medium effect size between the T2-weighted MR imaging-depicted white matter lesions and performance on tests of fluid-type intelligence. No significant correlation was demonstrated between white matter lesion ratings and tests of crystallized intelligence.

CONCLUSION

Lower fluid-type ("prevailing") intelligence test scores were associated with increased severity of white matter lesion ratings but not crystallized-type ("premorbid") intelligence test scores. This indicates that MR imaging-depicted white matter lesions are of clinical importance.

Performance on the Test of Everyday Attention and standard tests of attention following severe traumatic brain injury

The Test of Everyday Attention (TEA) was designed to address some of the limitations of established measures of attention. However, very few studies have examined its clinical utility. A group of 35 patients who had sustained a severe TBI were compared with 35 age- and education-matched controls on the TEA, Stroop, SDMT, WMS-R Digit Span, Ruff 2s and 7s Selective Attention Test, and PASAT. Of the TEA subtests, only the Map and Telephone Search subtests of the TEA produced significant differences between the two groups, suggesting a deficit in visual selective attention following TBI. Principal components analysis revealed a four-component / factor structure of attention, largely consistent with previous studies. A logistic regression found that the TEA Map Search and Modified Colour-Word subtest of the Stroop were best able to discriminate between the TBI and control groups. When the TBI group was divided into Early ( < 1 year post injury) and Late ( > 2 years post injury) groups, there was an additional deficit on the Lottery (sustained attention) subtest in the Early TBI group, indicating that there is some recovery in attentional function beyond 1 year post injury.

The covert orienting of visual attention following severe traumatic brain injury

Attentional problems have frequently been identified following traumatic brain injuries (TBIs) using both clinical assessments and self-report measures. Unfortunately, most measures of attention do not enable us to determine the underlying basis of these attentional deficits. One exception is Posner's Covert Orienting of Attention Task (COAT), which is designed to identify some of the fundamental mental operations underlying attention. This study sought to determine whether the COAT task could identify discrete attentional deficits following TBI beyond those caused by reduced speed of information processing. Thirty five patients who had sustained a severe TBI were compared to 35 age-matched controls. Results revealed that, although the reaction times of the patients with TBI were significantly slower than the controls, there were no differences between the two groups in terms of their ability to disengage, move, and engage their attention. The introduction of a secondary (language) task produced no significant difference between the two groups on the COAT task. However, there was a significant difference between the two groups on the language-based task, suggesting a deficit in auditory-verbal attention under dual task conditions.

The NART as an index of prior intellectual functioning: a retrospective validity study covering a 66-year interval

BACKGROUND

The National Adult Reading Test (NART) is widely used in research and clinical practice as an estimate of pre-morbid or prior ability. However, most of the evidence on the NART's validity as a measure of prior intellectual ability is based on concurrent administration of the NART and an IQ measure.

METHOD

We followed up 179 individuals who had taken an IQ test (the Moray House Test) at age 11 and administered the NART and the Mini-Mental State Examination (MMSE) at age 77. A subset (N = 97) were also re-administered the original IQ test.

RESULTS

The correlation between NART performance at age 77 and IQ age 11 was high and statistically significant (r = 0.73; P < 0001). This correlation was comparable to the correlation between NART and current IQ, and childhood IQ and current IQ, despite the shared influences on the latter variable pairings. The NART had a significant correlation with the MMSE but this correlation fell to near zero (r = 0.02) after partialling out the influence of childhood IQ.

DISCUSSION

The pattern of results provides strong support for the claim that the NART primarily indexes prior (rather than current) intellectual ability.

Estimating premorbid IQ from demographic variables: a comparison of a regression equation vs. clinical judgement

OBJECTIVES

To assess the accuracy with which clinicians estimate premorbid IQ from demographic variables and compare it with a regression equation which uses the same information.

DESIGN

Repeated measures and correlational.

METHODS

Sixty participants were administered the WAIS-R and had their demographic variables recorded (age, sex, years of education and occupation). Eight clinical psychologists estimated the participants' IQs from the demographic variables. Estimated IQs were also obtained using a regression equation developed by Crawford and Allan (1997).

RESULTS

The correlation between obtained IQ and the equation-based estimate was significantly higher than the correlation between obtained IQ and the clinicians' estimates. Further, mean estimated IQ from the regression equation did not differ significantly from obtained IQ whereas the means for four of the eight clinicians' estimates did differ significantly.

CONCLUSIONS

Demographic-based regression equations can provide unbiased and useful estimates of premorbid IQ; these estimates can be modified in the light of the additional qualitative information available to the clinician.

The CRABEL score--a method for auditing medical records

Medical record keeping has become increasingly important particularly for research, audit and medico-legal purposes. The authors present a protocol, the CRABEL score, that is quick and easy to use for the assessment of the quality of medical record keeping with the purpose of standardizing the audit of medical records and improving their quality.

Performance on the Modified Card Sorting Test by normal, healthy individuals: relationship to general intellectual ability and demographic variables

OBJECTIVES

The aim of this study was to obtain normative data for the Modified Card Sorting Test (MCST), and to examine the relationship between performance on this task, general intellectual ability and demographic variables.

DESIGN

A sample of 146 healthy individuals was tested with a demographic distribution (age, sex, socioeconomic class) similar to that of the British population.

METHODS

The MCST and the Wechsler Adult Intelligence Scales--Revised were administered to 146 people aged between 16 and 75 years.

RESULTS

Most people (56.6%) completed six categories, and many people made perseverative errors. Approximately 8% of the participants made over 50% perseverative errors. Performance on the MCST varied with age, years of education and general intellectual ability. Individuals with a Full Scale Intelligence Quotient (FSIQ) below 100 showed much more variability in performance than individuals with an FSIQ over 100. Detailed percentile norms for the performance on different indices of the test are presented.

CONCLUSIONS

The performance of individuals on the MCST is more closely associated with general intellectual ability than with demographic variables.

Extracellular calcium regulates HeLa cell morphology during adhesion to gelatin: role of translocation and phosphorylation of cytosolic phospholipase A2

Attachment of HeLa cells to gelatin induces the release of arachidonic acid (AA), which is essential for cell spreading. HeLa cells spreading in the presence of extracellular Ca2+ released more AA and formed more distinctive lamellipodia and filopodia than cells spreading in the absence of Ca2+. Addition of exogenous AA to cells spreading in the absence of extracellular Ca2+ restored the formation of lamellipodia and filopodia. To investigate the role of cytosolic phospholipase A2 (cPLA2) in regulating the differential release of AA and subsequent formation of lamellipodia and filopodia during HeLa cell adhesion, cPLA2 phosphorylation and translocation from the cytosol to the membrane were evaluated. During HeLa cell attachment and spreading in the presence of Ca2+, all cPLA2 became phosphorylated within 2 min, which is the earliest time cell attachment could be measured. In the absence of extracellular Ca2+, the time for complete cPLA2 phosphorylation was lengthened to <4 min. Maximal translocation of cPLA2 from cytosol to membrane during adhesion of cells to gelatin was similar in the presence or absence of extracellular Ca2+ and remained membrane associated throughout the duration of cell spreading. The amount of total cellular cPLA2 translocated to the membrane in the presence of extracellular Ca2+ went from <20% for unspread cells to >95% for spread cells. In the absence of Ca2+ only 55-65% of the total cPLA2 was translocated to the membrane during cell spreading. The decrease in the amount translocated could account for the comparable decrease in the amount of AA released by cells during spreading without extracellular Ca2+. Although translocation of cPLA2 from cytosol to membrane was Ca2+ dependent, phosphorylation of cPLA2 was attachment dependent and could occur both on the membrane and in the cytosol. To elucidate potential activators of cPLA2, the extracellular signal-related protein kinase 2 (ERK2) and protein kinase C (PKC) were investigated. ERK2 underwent a rapid phosphorylation upon early attachment followed by a dephosphorylation. Both rates were enhanced during cell spreading in the presence of extracellular Ca2+. Treatment of cells with the ERK kinase inhibitor PD98059 completely inhibited the attachment-dependent ERK2 phosphorylation but did not inhibit cell spreading, cPLA2 phosphorylation, translocation, or AA release. Activation of PKC by phorbol ester (12-O-tetradecanoylphorbol-13-acetate) induced and attachment-dependent phosphorylation of both cPLA2 and ERK2 in suspension cells. However, in cells treated with the PKC inhibitor Calphostin C before attachment, ERK2 phosphorylation was inhibited, whereas cPLA2 translocation and phosphorylation remained unaffected. In conclusion, although cPLA2-mediated release of AA during HeLa cell attachment to a gelatin substrate was essential for cell spreading, neither ERK2 nor PKC appeared to be responsible for the attachment-induced cPLA2 phosphorylation and the release of AA.

Payne and Jones revisited: estimating the abnormality of test score differences using a modified paired samples t test

Payne and Jones (1957) presented a useful formula for estimating the abnormality of differences between an individual's scores on two tests. Extending earlier work by Sokal and Rohlf (1995) and Crawford and Howell (in press), we developed a modified paired samples t test as an alternative to this formula. Unlike the Payne and Jones formula, the new method treats data from a normative or control sample as sample statistics rather than as population parameters. Technically, the new method is more appropriate for any comparison of an individual's difference score against normative data. However, it is most useful when the normative data is derived from samples with modest Ns; in these circumstances the Payne and Jones method overestimates the abnormality of differences. We suggest that the modified t test can be a useful tool in clinical practice and in single-case research. A computer program is made available that automates the calculations involved and can be used to store relevant data for future use.

Regression equations in clinical neuropsychology: an evaluation of statistical methods for comparing predicted and obtained scores

Regression equations are widely used in clinical neuropsychology, particularly as an alternative to conventional normative data. In neuropsychological applications the most common method of making inferences concerning the difference between an individual's test score and the score predicted by a regression equation is to multiply the standard error of estimate by an appropriate value of z to form confidence limits around the predicted score. The technically correct method is to calculate the standard error of a new individual Y and multiply it by the value of t corresponding to the desired limits (e.g., 90% or 95%). These two methods are compared in data sets generated to be broadly representative of data sets used in clinical neuropsychology. The former method produces confidence limits which are narrower than the true confidence limits and fail to reflect the fact that limits become wider as scores on the predictor deviate from the mean. However, for many of the example data sets studied, the differences between the two methods were trivial, thereby providing reassurance for those who use the former (technically incorrect) method. Despite this, it would be preferable to use the correct method particularly with equations derived from samples with modest Ns, and for individuals with extreme scores on the predictor variable(s). To facilitate use of the correct method a computer program is made available for clinical practice.

WAIS-R short forms: assessing the statistical significance of subtest differences

OBJECTIVES

To assist with analysis, in the individual case, of subtest profiles obtained from WAIS-R short-form administrations. Secondly, to offer a method of profile analysis for a full-length WAIS-R which is appropriate for use with age-graded scaled scores.

DESIGN

The study used a psychometric method for profile analysis (Silverstein, 1982a) which deals more effectively than alternative approaches with the problems raised by conducting multiple comparisons.

METHODS

A formula to compute the standard error of the difference between a subtest and mean subtest scores was applied to nine short forms and the full-length WAIS-R. The data used were derived from the WAIS-R standardization sample.

RESULTS

Tables for examining whether there are significant subtest differences in a clients WAIS-R profile are presented.

CONCLUSIONS

An elegant method of analysing subtest profiles has been extended to permit its use with WAIS-R short forms. Guidance on the use of the tables is offered; the distinction between reliable and abnormal differences is highlighted.

Assessing the reliability and abnormality of subtest differences on the Test of Everyday Attention

OBJECTIVES

To assist clinicians with the analysis of an individual's profile of subtest strength and weaknesses on the Test of Everyday Attention (TEA).

DESIGN

The study applied psychometric methods for the quantitive analysis of subtest profiles (Silverstein, 1982, 1984a, b).

METHODS

Formulae to compute the standard error of the difference and standard deviation of the difference between a subtest and a client's mean subtest scores were applied to determine critical values for reliable and abnormal differences. The data used were derived from the TEA standardization sample (N = 154).

RESULTS

Tables for examining whether an individual's TEA subtest profile contains reliable and abnormal subtest discrepancies are presented.

CONCLUSIONS

Elegant methods of analysing a subtest profile were extended for use with the Test of Everyday Attention. In keeping with the rationale underlying the measurement of neuropsychological deficit (Lezak, 1995), these methods complement the existing TEA normative comparison standards by providing individual comparison standards for a client's performance. Guidance on the use of the tables is offered; the distinction between reliable and abnormal differences is highlighted.

Base rate data on the abnormality of subtest scatter for WAIS-R short-forms

Tables are presented which permit clinicians to determine the abnormality of a WAIS-R subtest profile when one of nine different short-forms has been administered. The tables record the discrepancy, between each subtest and the individual's mean subtest score, which must be exceeded to occur in less than 15 per cent or 5 per cent of the healthy population. Two tables are provided; the first uses a statistical formula developed by Silverstein (1984a) to estimate the discrepancies from the US standardization sample. The second presents empirically derived discrepancies based on a sample of 326 healthy individuals which was representative of the adult UK population in terms of age, sex and social class distributions. The UK sample was also used to generate base rate data on the cumulative number of abnormal subtest deviations exhibited by healthy individuals.

Verbal knowledge and speed of information processing as mediators of age differences in verbal fluency performance among older adults

Age-related declines in verbal fluency among a large sample of older adults were investigated. Background variables, verbal knowledge, and speed of processing were examined as predictors of verbal fluency and as mediators of age effects. As expected, age-related declines were greater on the excluded letter fluency task than on the initial letter fluency task. Verbal knowledge was a better predictor of initial letter fluency than speed of processing, whereas the reverse was true for excluded letter fluency. However, speed of processing accounted for more of the age-related variance in both fluency measures than the other predictors. There was no evidence of verbal knowledge compensating for age-related declines in verbal fluency. Results suggest that verbal fluency performance is well maintained in late life and that any age-related decline appears to be mainly due to declines in speed of information processing.

The relationships between psychometric intelligence and learning in an explicit and an implicit task

An experiment is reported examining the relation of implicit grammar learning and series completion tasks to a standard measure of psychometric intelligence, the Wechsler Adult Intelligence Scale-Revised (WAIS-R; D. Wechsler, 1981). The results replicate and extend an earlier study by A. S. Reber, F. F. Walkenfeld, and R. Hernstadt (1991) and provide the following support for the differences between explicit and implicit tasks: (a) The implicit task was less strongly related to Full Scale IQ, and (b) the implicit task appeared to be independent of age. The implicit and explicit tasks exhibited a quite different pattern of relations to the factors known to underlie WAIS-R performance. Although both tasks showed significant links with a Perceptual Organization factor, only the series completion task showed a significant link with the Attention factor.

The relationships between psychometric intelligence and learning in an explicit and an implicit task

An experiment is reported examining the relation of implicit grammar learning and series completion tasks to a standard measure of psychometric intelligence, the Wechsler Adult Intelligence Scale-Revised (WAIS-R; D. Wechsler, 1981). The results replicate and extend an earlier study by A. S. Reber, F. F. Walkenfeld, and R. Hernstadt (1991) and provide the following support for the differences between explicit and implicit tasks: (a) The implicit task was less strongly related to Full Scale IQ, and (b) the implicit task appeared to be independent of age. The implicit and explicit tasks exhibited a quite different pattern of relations to the factors known to underlie WAIS-R performance. Although both tasks showed significant links with a Perceptual Organization factor, only the series completion task showed a significant link with the Attention factor.

WAIS-R short-forms: criterion validity in healthy and clinical samples

Regression equations developed by Crawford, Allan & Jack (1992) to estimate full-length WAIS-R IQs from seven short-forms were evaluated in healthy (N = 153) and neurological (N = 471) cross-validation samples. In the healthy sample the correlations between the short-forms and full-length IQs did not differ significantly from those obtained by Crawford et al. (1992). In the neurological sample the six- and seven-subtest short-forms, proposed by Crawford et al. (1992) and Warrington, James & Maciejewski (1986) respectively, differed from the other short-forms in that they had significantly higher criterion validity coefficients and did not systematically under- or overestimate IQs.

WAIS-R subtest scatter: base-rate data from a healthy UK sample

Base-rate data on subtest scatter for the WAIS-R was obtained from a sample of 200 healthy subjects recruited to match the adult UK population in terms of age, sex and social class distribution. Tables are presented which permit an assessment of the abnormality (i.e. rarity) of an individual's pattern of WAIS-R performance in terms of subtest range and subtest deviations from an individual's subtest mean. Guidance on the appropriate use of the tables is offered and the data are compared with data from the US WAIS-R standardization sample where appropriate. The distinction between reliable and abnormal differences is highlighted.

The WAIS-R(UK): basic psychometric properties in an adult UK sample

The WAIS-R is the most widely used measure of intellectual ability in the UK, despite never having been standardized in this country. The present study examined the psychometric properties of the WAIS-R in a sample of 200 subjects, which was representative of the adult UK population in terms of the distributions of age, sex and social class. The properties of the three IQ scales, i.e. the FSIQ, the VIQ and the PIQ, were found to be very similar to those reported for the US standardization sample: the scores were normally distributed, with means close to the desired value of 100; moreover, the reliabilities of the IQ scales were extremely high and closely matched the US reliabilities. There were also indications, however, that the scales have restricted standard deviations when used in the UK. The reliabilities of the 11 original subtests ranged from moderate to high and the majority were similar to the US reliabilities. However, in addition to evidence of restricted SDs, significant differences (sometimes as much as two-thirds of an SD) were found among the subtest means. These in-built subtest discrepancies could lead to erroneous conclusions about an individual's performance. A conversion table for UK test users is provided to overcome this problem.

Cognitive performance in UK sample of presymptomatic people carrying the gene for Huntington's disease

This paper presents an investigation of cognitive ability in 30 subjects at risk for Huntington's disease. Those shown to be at high or low risk for this disease are compared on a wide range of neuropsychological measures. Results indicate only one significant difference between the two groups; those who carry the gene show a higher level of performance on the Corsi Supraspan task. It is suggested, however, that minimal deficits are apparent in the at risk gene carrying group but that current measures of assessment are not sensitive enough to identify them.

The Mahalanobis Distance index of WAIS-R subtest scatter: psychometric properties in a healthy UK sample

Burgess (1991) has proposed a new index of subtest scatter for the WAIS-R which uses a test statistic, the Mahalanobis Distance (MD). When used with the WAIS-R, MD scores should be distributed as chi square with 11 degrees of freedom. The suitability of the MD index for UK clinical practice was assessed by examining its psychometric properties in a sample of 200 healthy subjects. The sample, which was representative of the adult UK population in terms of age, sex, and social class distribution, was administered a full-length WAIS-R. A goodness-of-fit test revealed that the sample distribution of MD scores did not deviate significantly from the chi square distribution. Furthermore, the percentage of subjects exceeding the critical value for significance at the .05 level (6.5 per cent) corresponded closely to the expected percentage (i.e. 5 per cent). It is concluded that the MD index is suitable for use in UK clinical practice. Demographic characteristics were only weakly related to MD scores which simplifies clinical interpretation.

Frontal lobe impairment in schizophrenia: relationship to intellectual functioning

Schizophrenic subjects (N = 48) and individually matched healthy controls were administered the Verbal Scale of the Wechsler Adult Intelligence Scale (VIQ) and a test of verbal fluency. The verbal fluency and VIQ scores of the schizophrenic subjects were significantly lower than the scores of the control subjects. An additional sample of healthy subjects (N = 144) was used to generate a regression equation for the prediction of verbal fluency scores from Verbal IQ and age. The verbal fluency scores obtained by the schizophrenic subjects were significantly lower than the scores predicted from the regression equation, whereas a significant difference was not obtained in the matched controls. These results provide further evidence of frontal lobe dysfunction in schizophrenia.

Severe hypoglycemia and intelligence in adult patients with insulin-treated diabetes

The IQ scores (WAIS-R) of 100 patients with insulin-treated diabetes (aged 25-52 yr) were compared with those of 100 healthy control subjects who were matched to the diabetic patients for sex, age, education, and social class. The diabetic group had lower WAIS-R performance and verbal IQ scores than the control group (P = 0.017 and P = 0.033, respectively) after controlling for premorbid IQ. The extent of the difference was modest, representing approximately 33% of an SD in IQ. When frequency of severe hypoglycemia was controlled for the difference in performance IQ between the diabetic patient group and the control group was abolished, whereas the difference between the groups in verbal IQ persisted. It is hypothesised that cumulative severe hypoglycemia might be the major factor in the slight performance IQ differences between diabetic patients and control subjects. The origin of the verbal IQ differences, although obscure, might be related to the social impact of the disorder.

Verbal fluency: a NART-based equation for the estimation of premorbid performance

A sample of 142 subjects free of neurological or psychiatric disorder were administered the National Adult Reading Test (NART) and a verbal fluency (VF) test. A highly significant correlation between the NART and VF was obtained indicating that premorbid ability should be taken into account when interpreting VF performance. A regression equation was built to estimate premorbid performance on VF from the NART. A highly significant difference between predicted and obtained VF was obtained in a sample of neurological patients (N = 38). For ease of use, a table converting NART errors to predicted VF scores is presented.