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.

This single-blind, placebo controlled study reports on the effects of administering three acute doses of nicotine (0.4, 0.6 and 0.8 mg) subcutaneously to a group of Alzheimer's disease (DAT) patients (n = 22), young adult controls (n = 24), and normal aged controls (n = 24). The study extends our previous findings obtained using smaller groups of subjects. Drug effects were examined on three computerised tests: the first measuring rapid visual information processing, sustained visual attention and reaction time (RVIP task); a delayed response matching to location-order task measuring sustained visual attention and visual short-term memory (DRMLO task); and a finger tapping test measuring simple reaction time (FT task). The critical flicker fusion test (CFF) was used as a measure of perception and the WAIS digit span forwards (DS), of auditory short-term memory. Tests were graded in difficulty, titrated to avoid floor and ceiling effects so that meaningful, direct comparisons between groups could be made. Nicotine significantly improved sustained visual attention (in both RVIP and DRMLO tasks), reaction time (in both FT and RVIP tasks), and perception (CFF task--both ascending and descending thresholds). Nicotine administration did not improve auditory and visual short-term memory. There were no consistent, overall patterns of difference in performance between smokers and non-smokers in the control groups, or between males and females in any group. Despite the absence of change in memory functioning, these results demonstrate that DAT patients have significant perceptual and visual attentional deficits which are improved by nicotine administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Nicotine in patients with dementia of the Alzheimer type (DAT) produced a significant and marked improvement in discriminative sensitivity and reaction times on a computerised test of attention and information processing. Nicotine also improved the ability of DAT patients to detect a flickering light in a critical flicker fusion test. These results suggest that nicotine may be acting on cortical mechanisms involved in visual perception and attention, and support the hypothesis that acetylcholine transmission modulates vigilance and discrimination. Nicotine may therefore be of some value in treating deficits in attention and information processing in DAT patients.

SynopsisA number of computerized tests were used to study visual attention, memory and learning in elderly depressed patients. Impairment was found in approximately 70% of depressed patients and was seen particularly in memory and in measures of latency. Depressed patients showed equivalent impairment in short-term memory but less impairment in conditional associative learning compared to a group of patients with early dementia of the Alzheimer-type (DAT), matched for age and pre-morbid IQ. With respect to qualitative differences between depression and DAT, depressed patients showed a different pattern of errors and a consistently prolonged latency of response which was independent of delay in a delayed matching-to-sample test. On recovery from depression, although improvement was seen in most test scores, performance in measures of latency and in a number of tests of memory and learning failed to reach the level seen in a group of matched control subjects and approximately 35% of patients continued to show impairment. For the depressed patients, ventricular brain ratio (VBR) correlated with measures of slowing. In addition, in the ‘recovered-depressives’, VBR correlated with poor performance at high levels of task difficulty. These findings are discussed with respect to previous literature on the pattern of cognitive impairment and CT scan findings in depression.

In a sample of 178 subjects with Alzheimer's disease, diagnosed by clinical criteria (NINCDS/ADRDA), delusions had occurred in 16% of the sample since the onset of the illness and been present within the last 12 months in 11%. Simple delusions of theft and suspicion were the most common types and a greater proportion of men suffered delusions of theft. Subjects with other types of delusion had relatively well preserved lateral ventricular size and basal ganglia calcification. Twenty per cent of the group had experienced persecutory ideation short of delusions since the onset of the illness. Cognitive function at entry to the study and cognitive deterioration over the succeeding 12 months was not influenced by the presence of disorders of thought content.