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We investigated the different mechanisms that may underlie deficits in verbal concept formation among patients with Alzheimer's disease (AD) and ischaemic vascular dementia (IVD) associated with periventricular and deep white matter alterations. Concept formation was assessed with the WAIS-R Similarities subtest (SIM). Two types of errors were re-coded from the 0-point responses as scored by the WAIS-R manual. In set errors (e.g., dog-lion "they're alive") were coded when patients reported a very vague superordinate concept for the word pair. Out of set responses (e.g., dog-lion "the lion roars and the dog barks") were coded when a response was clearly out of mental set, i.e., when participants were unable to provide a superordinate concept for the word pair. Between-group comparisons demonstrated no difference in SIM test performance according to the scoring system described in the WAIS-R manual. Nonetheless, AD patients produced a greater proportion of in set errors, while IVD patients produced a greater proportion of out of set errors. Out of set errors were highly associated with measures of executive function, while in set errors were associated with measures related to delayed recognition memory and semantic intrusion errors. We conclude that the underlying deficits that contribute to poor concept formation differ between AD and IVD patients. In IVD impaired concept formation is related to deficits in the executive systems necessary to monitor responses and sustain mental set. In AD, by contrast, the deficit appears to be secondary to impaired verbal response selection.

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Visuoconstructional ability was assessed by asking patients diagnosed with Alzheimer's disease (AD), ischaemic vascular dementia (IVD), and Parkinson's disease (PD) and a normal control group (NC) to copy a modification of the Rey-Osterrieth Complex Figure (M-ROCF). The drawings of the NC group were superior to all dementia participants. AD patients generally outperformed IVD and PD patients; however, there were few differences between IVD and PD groups. Nonetheless, the drawings of IVD and PD patients were very fragmented and contained numerous perseverations and omissions. Despite these errors, patients with IVD and PD obtained higher delayed recognition memory scores than AD patients. Correlational analyses among dementia patients between neuropsychological tests and the copy of the M-ROCF found that accurate figure copy was most consistently correlated with tests of working memory, that is, tests requiring patients to monitor their behavior and sustain a complex mental set while performing mental manipulations. By contrast, no relationship between executive function tests related to measures of response selection/inhibition or other domains of neuropsychological functioning was found.

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This research investigated whether subjects with Alzheimer's disease (AD) and ischaemic vascular dementia (IVD) associated with periventricular and deep white matter alterations can be dissociated on tests of declarative and procedural memory, as well as on MRI indices of white matter alterations and the size of the hippocampal formation. The California Verbal Learning Test (CVLT) and the Pursuit Rotor Learning Tests (PRLT) were used to measure declarative and procedural memory, respectively. Subjects with IVD obtained a higher score on the CVLT recognition discriminability index; however, on the PRLT total time on target, carry-over between trial blocks, and slope calculated for all test trials was low. Subjects with AD exhibited the opposite profile. MRI studies indicated that subjects with IVD had considerably greater white matter alterations, but larger hippocampal formations than subjects with AD. Higher scores on the CVLT recognition discriminability index were correlated with increased size of the body of the hippocampus and parahippocampal gyrus. By contrast, as the severity of white matter alterations increased the slope on the PRLT declined. In sum, subjects with AD and IVD can be dissociated on the basis of differing patterns of impairment on tests of declarative and procedural memory, and MRI indices of white matter alteration and the integrity of the hippocampal formation.

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Perseverative behavior has not been extensively studied in patients with dementia. In this study, perseverative behavior was elicited with the dementia version of the Graphical Sequence Test. A control group and participants with Alzheimer's disease (AD) and subcortical ischemic vascular dementia (IVD) were studied. A factor analysis revealed a 3-factor model consisting of perseverations related to semantic knowledge, motor functioning, and a third, intermediary factor. IVD participants made more total perseverations than did AD participants. Perseverations made by AD participants were correlated with deficits on tests of semantic knowledge, whereas the perseverations made by IVD participants were correlated with motor and frontal systems tests. Results are consistent with the view that perseverative behavior is hierarchically arranged in terms of specific levels of cognitive complexity and the overall pattern of cognitive deficits associated with each type of dementia.

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The underlying mechanisms for impaired output on letter (F, A, and S) and category (e.g., animal) word list generation (WLG) tasks in subcortical ischemic vascular dementia (IVD) were investigated. Normal control (NC) and Alzheimer's disease (AD) participants were also studied. IVD and NC participants performed better on category than letter WLG tasks, whereas the opposite was observed among AD participants. IVD participants produced fewer responses than AD participants on letter WLG tasks, but there was no difference between AD and IVD participants on the "animal" WLG task. AD participants scored lower than IVD and NC participants on animal WLG indexes measuring semantic knowledge. There were few differences between IVD and NC participants. The reduced output on the animal WLG task for IVD participants is consistent with search-retrieval deficits. The reduced output of AD participants may be caused by degraded semantic knowledge.

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This research examined the neuropsychological functioning of demented patients with periventricular and deep white matter alterations. Thirty-three outpatients with NINCDS-ADRDA probable Alzheimer's disease (AD) and 27 outpatients with probable/ possible ischaemic vascular dementia (IVD, Chui et al., 1992) associated with periventricular and deep white matter alterations matched for age, education, level of dementia, and functional disability were studied. White matter alterations were measured using a 40-point scale previously described by Junque et al. (1990). Subjects with cortical CVAs were excluded. On executive control tests, IVD subjects made more preservations on tests of mental control and response set, and produced fewer responses on phonemic controlled oral word association tests (letters: F,A,S). IVD subjects also made more preservations and graphomotor errors on clock drawings. On the California Verbal Learning Test the IVD group performed better than AD subjects on the short delay free recall test condition, the recognition discriminability index, and made fewer intrusion errors on both free and cued recall conditions. We conclude that neuropsychological assessment can differentiate AD from IVD associated with white matter alterations, and that the neuropsychological profile of demented subjects with significant periventricular and deep white matter alterations is similar to other subcortical dementing illnesses.

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We report the case of a 67-year-old woman who experienced a sudden onset of psychotic illness (i.e., prominent delusions and hallucinations) that has endured for approximately 3 years. As part of her neurobehavioral work-up, a SPECT scan revealed right frontal and left anterior temporal-lobe hypoperfusion. Serial neuropsychological evaluations obtained 2 years apart demonstrated a steady decline on tests of executive control (monitoring, allocation of attention, perseveration) and visuospatial abilities, whereas performance in other areas of cognitive functioning have remained steady and in the normal range for the patient's age. Over this same period of time, serial EEG, MRI, and neurology examinations have been within normal limits. Thus, there was little evidence with which to diagnose dementia. It is suggested that concomitant impairment in executive control, coupled with a degraded capacity to process perceptual information, can give rise to enduring psychotic behavior.

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In a previous article we described a 10-point scoring system (i.e., scale 1) to grade clock drawings to command and copy with hands set for "ten after 11" among demented patients. Alzheimer's subjects (AD) improved from the command to copy conditions, whereas subjects with ischaemic vascular dementia (IVD) did not. To investigate the underlying cognitive deficits responsible for this profile, an additional scale was developed (scale 2) that tallied errors in graphomotor functioning, hand/number placement, and executive control. On an independent sample of subjects, AD subjects, again, made significant improvement on scale 1 from the command to copy condition, whereas no such improvement occurred among the IVD subjects. On scale 2, IVD subjects made more graphomotor errors in the command condition, and more executive control and more total errors in the copy conditions than AD subjects. A number of positive correlations were noted between tests of language and memory on scale 1. By contrast, scores on tests of executive control declined as scale 2 errors increased. In addition, a principal component analysis indicated that scale 2 test performance loaded on a factor with other tests related to executive control. These results suggest that impairment in frontal systems functioning may explain why IVD subjects do not improve from the command to copy conditions on scale 1. Such a pattern of performance in clock drawing may also be helpful in making a differential diagnosis between AD and IVD.

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Misidentification syndromes represent false, delusionally-based identification of self and/or others. These are variants of the Capgras Syndrome. Although the frequency of misidentification syndromes in schizophrenic populations has not yet been established, the authors believe this syndrome is more prevalent than previously described. Seven of twenty-five (28%) consecutive patients admitted to a chronic clozapine unit with a variant of misidentification syndrome will be described. Their symptoms are categorised according to traditional classification, and Silva's proposed nomenclature. Problems inherent in these classifications are discussed. The need for a more systematic classification of misidentification syndromes is emphasised. Longitudinal studies of misidentification syndrome, and the development of a standardised assessment tool for clinicians who treat chronically psychotic patients, are encouraged.

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