Groups of patients with dementia of Alzheimer type (DAT) and idiopathic Parkinson's disease, together with age and IQ-matched normal controls, were compared on several computerized tests of visuospatial memory and learning. Two different groups of parkinsonian patients were studied: (1) a newly diagnosed group, early in the course of the disease, not receiving medication (NMED) PD) and (2) a group later in the course of the disease, receiving medication (MED PD). The DAT and MED PD group were significantly impaired in both spatial and visual pattern recognition memory. The DAT group exhibited a delay-dependent deficit (over 0-16 s) in a delayed matching-to-sample procedure, but were not impaired at simultaneous-matching-to-sample. By contrast, the MED PD group showed delay-independent deficits in the delayed matching-to-sample test and both the MED PD and the NMED PD group were also significantly impaired in simultaneous matching. In a form of delayed response test, the subjects were required first to memorize and then to learn the locations of several abstract visual stimuli which varied progressively in number from 1 to 8. The DAT group were severely impaired in this conditional associative learning task. A significant proportion of patients, but none of the controls, in the NMED and MED PD group also failed the test at the levels of 6 or 8 items. There was a significant correlation between the performance on the first trial, memory score in the delayed response task and indices of clinical disability and disease duration in the patients with Parkinson's disease. The results are discussed in terms of the utility of the comparison between DAT and PD in characterizing the nature of the cognitive deficits in these conditions and their relation to those findings from animal neuropsychology which use comparable paradigms.

Background:As the population ages, it is increasingly important to use effective short cognitive tests for suspected dementia. We aimed to review systematically brief cognitive tests for suspected dementia and report on their validation in different settings, to help clinicians choose rapid and appropriate tests.Methods:Electronic search for face-to-face sensitive and specific cognitive tests for people with suspected dementia, taking ≤ 20 minutes, providing quantitative psychometric data.Results:22 tests fitted criteria. Mini-Mental State Examination (MMSE) and Hopkins Verbal Learning Test (HVLT) had good psychometric properties in primary care. In the secondary care settings, MMSE has considerable data but lacks sensitivity. 6-Item Cognitive Impairment Test (6CIT), Brief Alzheimer's Screen, HVLT, and 7 Minute Screen have good properties for detecting dementia but need further validation. Addenbrooke's Cognitive Examination (ACE) and Montreal Cognitive Assessment are effective to detect dementia with Parkinson's disease and Addenbrooke's Cognitive Examination-Revised (ACE-R) is useful for all dementias when shorter tests are inconclusive. Rowland Universal Dementia Assessment scale (RUDAS) is useful when literacy is low. Tests such as Test for Early Detection of Dementia, Test Your Memory, Cognitive Assessment Screening Test (CAST) and the recently developed ACE-III show promise but need validation in different settings, populations, and dementia subtypes. Validation of tests such as 6CIT, Abbreviated Mental Test is also needed for dementia screening in acute hospital settings.Conclusions:Practitioners should use tests as appropriate to the setting and individual patient. More validation of available tests is needed rather than development of new ones.

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SUMMARY Twenty patients satisfying standard clinical criteria for Alzheimer's disease (AD) and six age-matched normal controls were studied using 9'Tc hexamethyl-propyleneamine oxime and single photon emission tomography. The AD patients had lower regional cerebral blood flow (rCBF) in the temporal and posterior parietal lobes compared to controls. AD patients with apraxia and aphasia had lower rCBF in the lateral temporal and posterior parietal lobes than AD patients without these features. Within the AD group, correlations were found between neuropsychological tests and rCBF: praxis correlated with posterior parietal activity, memory with left temporal lobe activity and language with activity throughout the left hemisphere.Neuroimaging has developed rapidly in the past few years with the introduction of x-ray computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET) and single photon emission tomography (SPET). CT and MRI offer unique anatomical information while PET and SPET reveal physiological functions such as cerebral blood flow and cerebral metabolism. 9'Tc hexamethyl-propyleneamine oxime (HMPAO) is a new radiopharmaceutical which crosses an intact blood brain barrier and is trapped inside functioning cells in proportion to cerebral blood flow (CBF).'2 Alzheimer's disease (AD) affects between 6 to 7% of the population over the age of 653 and represents a major health issue. The cause is not known and no effective treatment exists. CT studies of subjects with AD have demonstrated abnormalities including cerebral atrophy and ventricular enlargement.4 MRI has demonstrated white matter lesions and abnormal spin lattice relaxation times.5 PET scanning has shown defects in metabolism in temporal and parietal lobes6 and similar results have been found using SPET.75 Although in some ways PET is the ideal way of studying functional imaging the technique is extremely expensive and requires a large highly trained technical staff.The majority of SPET studies in dementia have attempted to describe the scan appearances in different types of dementia and to assess the ability of the

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