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author:("wichmand, B")
1.  Pathological gambling after bilateral subthalamic nucleus stimulation in Parkinson disease 
We describe a patient with advanced Parkinson's disease who developed pathological gambling within a month after successful bilateral subthalamic nucleus (STN) stimulation. There was no history of gambling. On neuropsychological testing, slight cognitive decline was evident 1 year after surgery. Stimulation of the most dorsal contact with and without medication induced worse performances on decision making tests compared with the more ventral contact. Pathological gambling disappeared after discontinuation of pergolide and changing the stimulation parameters. Pathological gambling does not seem to be associated with decision making but appears to be related to a combination of bilateral STN stimulation and treatment with dopamine agonists.
PMCID: PMC2117849  PMID: 17210626
2.  Does chronic subthalamic nucleus stimulation in advanced Parkinson's disease cause invalidating cognitive and behavioural dysfunctions? 
Cognitive and behavioural dysfunctions in patients with Parkinson's disease
PMCID: PMC2117650  PMID: 17308286
3.  Cognitive functioning in patients with suspected chronic toxic encephalopathy: evidence for neuropsychological disturbances after controlling for insufficient effort 
Chronic toxic encephalopathy (CTE) caused by long term occupational exposure to organic solvents is still a controversial disorder. Neuropsychological testing is the cornerstone for diagnosing the syndrome, but can be negatively influenced by motivational problems. In this nationwide study, we investigated the neuropsychological functioning and psychological symptoms of a large group of patients with suspected CTE, and ruled out alternative explanations for their complaints, including suboptimal performance due to insufficient effort.
We studied participants with suspected CTE (n = 386) who were referred for further diagnosis to the Netherlands Centre of Occupational Diseases in the period 1998–2003 and who had completed the entire diagnostic protocol. Patients were excluded if there was the slightest suspicion that test performance had been negatively influenced by insufficient effort (n = 221), or if comprehensive assessment identified an alternative diagnosis (n = 80). Insufficient effort was defined by a combination of three indices. The neuropsychological test scores of the patient group (n = 85) were compared with those of a control group of building trade workers matched for sex, age, and educational level (n = 35).
The patient group had significantly more psychological complaints and performed significantly worse than the control group on tests of speed of information processing and memory and learning. However, only a small percentage of the patients had clearly abnormal scores for cognitive speed (9%) or memory (8%). Attention, verbal abilities, and constructional functions were not disturbed. Exposure duration and cognitive complaints were significantly correlated, whereas the correlation between exposure duration and neuropsychological domain scores was not significant.
Insufficient effort was present in a substantial part of the patient group. After minimising the likelihood that insufficient effort negatively influenced neuropsychological scores, we still found neuropsychological deficits in speed of cognitive processing and memory; however, these scores were clearly abnormal only in a minority of patients with suspected CTE. Screening instruments should focus on these domains.
PMCID: PMC2077719  PMID: 16484635
chronic toxic encephalopathy; malingering; neuropsychological tests; solvents/toxicity; occupational diseases; cognitive disorders
4.  The seven minute screen: a neurocognitive screening test highly sensitive to various types of dementia 
Background: The seven minute screen (7MS) is a compilation of the temporal orientation test, enhanced cued recall, clock drawing, and verbal fluency. It has been shown to be useful for detecting Alzheimer's disease in a population of patients with memory complaints.
Objective: To assess the predictive validity of the 7MS for various types of dementia, and the influence of depression and other psychiatric conditions on 7MS scores.
Setting: Multicentre: secondary referral sites across the Netherlands.
Subjects: 542 patients with various types of dementia or depression, together with 45 healthy controls.
Results: Alzheimer's disease was diagnosed in 177 patients, other types of dementia in 164. The sensitivity of the 7MS for Alzheimer's disease was 92.9% with a specificity of 93.5%. For other types of dementia the sensitivity was 89.4% and the specificity 93.5%. Cognitive abnormalities were found in 71% of the patients with depression (n = 31). The mean (SD) duration of administration of the 7MS was 12.4 (4.6) minutes, range 8 to 22, depending on dementia severity.
Conclusions: The 7MS is a useful screening tool for discriminating patients with dementia from cognitively intact patients. This not only applies to Alzheimer's disease but also to other types of dementia. Specificity with respect to depression was lower for the 7MS than for the MMSE.
PMCID: PMC1763549  PMID: 15090563
5.  Visual association test to detect early dementia of the Alzheimer type 
Background: The visual association test (VAT) is a brief learning task based on imagery mnemonics. The test materials consist of six line drawings of pairs of interacting objects or animals—for example, an ape holding an umbrella. The person is asked to name each object and, later, is presented with one object from the pair and asked to name the other.
Objective: To verify that the task induces robust incidental or effortless learning (study 1), and to study the efficiency of the test as a discriminator between early dementia of the Alzheimer type (DAT) and non-demented people (study 2) and non-DAT types of dementia (study 3).
Methods: Study 1: two groups of elderly volunteers were administered the VAT. The stimuli were presented in the interactive fashion to group A—for example, a monkey carrying an umbrella (n=83)—and side by side to group B—for example, separate pictures of a monkey alone and an umbrella alone (n=79). Group B received learning instructions, but group A did not. Study 2: three groups of subjects were selected from a population based follow up study: incident DAT cases (n=24), cognitively declining subjects not diagnosed with dementia (n=21), and stable non-demented subjects (n=204). Test performance of the non-demented group at baseline was compared with that of patients with DAT at the time of their diagnosis, of patients with DAT a year before their diagnosis, and of non-demented declining subjects at baseline. Study 3: subjects were patients referred for neuropsychological assessment because of suspected dementia. They were diagnosed by consensus criteria of various dementia syndromes.
Results: Study 1: recall was more than twice as high in group A as in group B. Thus interactive presentation, even in the absence of learning instructions, enhances learning. Study 2: at a level of 97.5% specificity, the VAT had a sensitivity of 87.5% for DAT cases at the time of diagnosis and 66.7% one year before diagnosis. The cognitively declining group scored significantly lower on the VAT at baseline than the non-demented group. The VAT discriminated more effectively than both the MMSE and the six item picture learning task from the CAMCOG. Study 3: VAT scores were significantly lower in patients with DAT (n=48) than in patients with vascular dementia (n=37), frontotemporal dementia (n=9), or subcortical dementia (n=15), but not lower than in patients with Lewy body dementia (n=7). Mean mini mental state examination scores of these groups were not significantly different. The VAT discriminated patients with DAT from patients with other types of dementia more effectively than a prose recall test. Sensitivity was 79% and specificity 69%.
Conclusions: The VAT detects with high specificity a sizeable proportion of patients with DAT a year before the diagnosis, and a low VAT score is relatively uncommon in patients with non-DAT dementia.
PMCID: PMC1737993  PMID: 12122168
6.  Outcome of unilateral pallidotomy in advanced Parkinson's disease: cohort study of 32 patients 
OBJECTIVES—In a randomised trial to study the efficacy of unilateral pallidotomy in patients with advanced Parkinson's disease, patients having pallidotomy within 1 month after randomisation were compared with patients having pallidotomy 6 months after the primary outcome assessment. Of the 37 patients enrolled 32 had a unilateral pallidotomy. The follow up study of these patients is presented to report (1) clinical outcome; (2) adverse effects; (3) cognitive and behavioural effects; (4) relation between lesion location and outcome; and (5) preoperative patient characteristics predictive for good outcome.
METHODS—Outcome measures were the motor section of the unified Parkinson's disease rating scale (UPDRS), levodopa induced dyskinesias, disability, quality of life, and a comprehensive neuropsychological assessment. Multivariate logistic regression was used to identify preoperative patient characteristics independently associated with good outcome.
RESULTS—Off phase assessment showed a reduction in parkinsonism from 49 to 36.5 points on the UPDRS 6 months after surgery. Improvements were also demonstrated for activities of daily living and quality of life. In the on phase dyskinesias were reduced. All effects lasted up to 12 months after surgery. Three patients had major permanent adverse effects. Besides worsening of verbal fluency after left sided surgery, systematic cognitive deterioration was not detected. Patients taking less than 1000 levodopa equivalent units (LEU)/day were more likely to improve.
CONCLUSIONS—The positive effects of unilateral pallidotomy are stable up to 1 year after surgery. Patients taking less than 1000 LEU per day were most likely to improve.

PMCID: PMC1737559  PMID: 11511714
7.  Cognitive complaints in patients after whiplash injury: the impact of malingering 
OBJECTIVES—The validity of memory and concentration complaints that are often reported after a whiplash trauma is controversial. The prevalence of malingering or underperformance in post-whiplash patients, and its impact on their cognitive test results were studied.
METHODS—The Amsterdam short term memory (ASTM) test, a recently developed malingering test, was used as well as a series of conventional memory and concentration tests. The study sample was a highly selected group of patients, who were examined either as part of a litigation procedure (n=36) or in the normal routine of an outpatient clinic (n=72).
RESULTS—The prevalence of underperformance, as defined by a positive score on the malingering test, was 61% (95% CI: 45-77) in the context of litigation, and 29% (95% CI: 18-40) in the outpatient clinic (p=0.003). Furthermore, the scores on the memory and concentration test of malingering post-whiplash patients (n=43) and non-malingering post-whiplash patients (n=65) were compared with the scores of patients with closed head injury (n=20) and normal controls (n=46). The malingering post-whiplash patients scored as low as the patients with closed head injury on most tests.
CONCLUSIONS—The prevalence of malingering or cognitive underperformance in late post-whiplash patients is substantial, particularly in litigation contexts. It is not warranted to explain the mild cognitive disorders of whiplash patients in terms of brain damage, as some authors have done. The cognitive complaints of non-malingering post-whiplash patients are more likely a result of chronic pain, chronic fatigue, or depression.

PMCID: PMC2169999  PMID: 9527145
8.  Relation between education and dementia: the role of test bias revisited. 
Several authors have suggested that dementia screening tests may be biased against low levels of education, whereas others find that a low level of education is a genuine risk factor for dementia. The present paper attempts to reconcile these conflicting views by examining item bias and test bias indices of the mini mental state examination (MMSE). Psychometric calculations and receiver operating characteristics (ROC) analyses of sensitivity and specificity as performed by earlier studies were replicated and extended from the database of the Amsterdam Study of the Elderly. This is a population survey on cognitive decline and dementia (age range 65-84). Subjects with a low level of education (primary school) were compared with better educated subjects (at least some secondary education). Cases were matched by age and sex. The results indicate that the MMSE is not educationally biased as far as item characteristics, reliability, and construct validity are concerned. Yet its predictive validity as a screening test for dementia is educationally biased. This bias will effectively be eliminated with a two point higher cut off score for the subjects whose education extends beyond primary school. Even after such score correction, a low level of education probably remains a genuine risk factor for dementia.
PMCID: PMC485993  PMID: 7629532

Results 1-8 (8)