PubMed Health⌕ Search

Biomedical subjects

C Flicker

Publications and source records attributed to C Flicker.

16 recordsLinked to original sources
PubMed1992

Hypersensitivity to scopolamine in the elderly.

Scopolamine hydrobromide, 0.43 mg/70 kg, was administered by subcutaneous injection to ten young and ten elderly subjects. A comprehensive neuropsychological test battery was used to assess the effects of scopolamine, as compared to placebo, on cognitive function. As previously reported for this group of young subjects, scopolamine significantly impaired performance on tests of recent memory and visuospatial praxis. The same effects were observed in the elderly subjects, but the magnitude of the effects was much larger. The scopolamine injections produced significant psychomotor slowing in the elderly, whereas higher doses of the drug are required to produce this effect in young subjects. In both young and old subjects scopolamine failed to affect immediate memory, language function, object sorting, and the frequency of intrusion errors (although trends toward an effect were more apparent in the elderly). Remote memory, tested in the elderly only, was also unaffected. The results suggest that scopolamine's cognitive effects are quantitatively more pronounced in elderly subjects than young subjects, but that they are qualitatively similar and do not constitute a valid model for the cognitive dysfunction associated with Alzheimer's disease.

Adolescent↗
PubMed1991

Mild cognitive impairment in the elderly: predictors of dementia.

We conducted full diagnostic evaluations, including a comprehensive cognitive assessment battery, of a group of 32 elderly subjects with a clinically identified mild cognitive impairment and a group of 32 age-matched and education-matched normal subjects. The mildly impaired subjects performed significantly more poorly than the controls on tests of recent memory, remote memory, language function, concept formation, and visuospatial praxis. Follow-up evaluations of cognitive status 2 years later revealed clinically detectable cognitive decline relative baseline in 23 (72%) of the mildly impaired subjects. Several of the objective psychological tests accurately discriminated at baseline between the decliners and nondecliners in the mildly impaired group. Among the 20 mildly impaired subjects with no complicating conditions, 16 exhibited cognitive deterioration between baseline and follow-up. These results suggest that most elderly subjects with mild cognitive deficits, as determined by clinical evaluation and objective psychological testing, will manifest the progressive mental deterioration characteristic of dementia and that psychometric predictors can be used to distinguish between benign and more significant underlying disorders in mildly impaired elderly subjects.

Aged↗
PubMed1990

Scopolamine effects on memory, language, visuospatial praxis and psychomotor speed.

Scopolamine hydrobromide was administered by subcutaneous injection to 30 young subjects in a dose of 0.22 mg/70 kg, 0.43 mg/70 kg, or 0.65 mg/70 kg. Treatment effects were compared to placebo on an extensive cognitive assessment battery. Almost all tests in the battery had been previously administered to Alzheimer's disease patients and nondemented elderly subjects. Scopolamine produced deficits on tests of verbal recall, visuospatial recall, visual recognition memory, visuospatial praxis, visuoperceptual function, and psychomotor speed. Immediate memory, language function, object sorting, and frequency of intrusion errors were unaffected. The low dose of scopolamine produced some peripheral anticholinergic signs but did not affect the cognitive measures. The results support the conclusion reached in previous studies that the cognitive profile of scopolamine-injected young subjects is more similar to that of the nondemented elderly than to that of Alzheimer's disease patients.

Adolescent↗
PubMed1990

Impaired facial recognition memory in aging and dementia.

Young normals, aged normals, and patients with early and advanced probable dementia of the Alzheimer type (DAT) were administered a facial recognition memory task. A continuous recognition paradigm was used, in which subjects were instructed to identify the repeated faces in an ongoing series of faces presented on a video monitor screen. A signal detection analysis of the data revealed that the DAT patients were markedly impaired in their ability to discriminate between new and repeated faces. Multiple presentations of faces improved the recognition accuracy of the early DAT patients only, but their rate of learning was slower than that of the normal subjects. In comparison to the young normals, elderly normals exhibited a mild deficit in recognition memory. All of the elderly subject groups exhibited a more liberal response bias than the young normals, which eliminates the possibility that the impaired memory task performance of the aged subjects could be attributed to a more conservative test-taking strategy. The DAT patients exhibited impaired recognition even when the second presentation of a face immediately followed the first, which perhaps implies that task performance was also sensitive to the effect of DAT on visuoperceptual abilities or psychomotor speed.

Adolescent↗
PubMed1988

Equivalent spatial-rotation deficits in normal aging and Alzheimer's disease.

Two tests of spatial-rotation ability were administered to 17 young normals, 23 aged normals, and 51 patients with diagnoses of Alzheimer's disease (AD). The AD patients consisted of 28 early dementia patients and 23 advanced dementia patients. On a computerized version of the Boston Naming Test, 40 objects were presented for naming, 20 of which were rotated 180 degrees. The subjects' capacity for mental rotation was assessed on the basis of their accuracy of naming of rotated vs. unrotated objects. On Money's Standardized Road Map Test, in which the subject is asked whether turns on a map are to the left or to the right, spatial-rotation ability was assessed on the basis of the subject's left-right orientation on turns with movement away from the subject (requiring no rotation) vs. turns with movement toward the subject (requiring rotation). Performance on both tasks was progressively worse in the young normal, aged normal, early dementia, and advanced dementia groups. Both tasks demonstrated a clear spatial-rotation deficit in the elderly. Although the spatial-rotation effect was superimposed upon deficits in naming and left-right orientation in the demented subjects, the magnitude of the rotation effect did not significantly differ in the aged normal vs. the early dementia group on either task, suggesting that early AD produces no further impairment of spatial-rotation abilities than is produced by normal aging.

Adolescent↗
PubMed1987

Implications of memory and language dysfunction in the naming deficit of senile dementia.

Young normals, elderly normals, and patients with either mild-to-moderate or severe senile dementia of the Alzheimer type (SDAT) were administered several tests of language function and remote memory. On all of the language tests examined, elderly normals exhibited a mild, nonsignificant performance decrement relative to the young normals. Advanced SDAT patients were markedly impaired on all of the tests. Early dementia patients were most impaired, relative to aged normals, on tests of object naming, category instance fluency, and remote memory. The deficit was smaller on the WAIS vocabulary subtest, on selecting the name of a visually presented object, and on recalling the function of an object. Early SDAT patients were least impaired in selecting the picture of an object after its name had been provided and in selecting objects that belong to a specified functional category. The results are consistent with the notion that the language dysfunction in early SDAT is due to a deficit in semantic memory function in which general, categorical information remains available whereas information about specific attributes becomes less accessible. The object naming test might be useful in the assessment of treatment effects upon SDAT because of its sensitivity and specificity to dementia, its high face validity, and its independence of recent memory.

Aged↗
PubMed1987

A visual recognition memory test for the assessment of cognitive function in aging and dementia.

Young, non-demented elderly, and elderly demented subjects were administered a computerized visual recognition memory task. In the task, subjects were instructed to point out the new object from a group of objects whose number was progressively incremented. The test was subject-paced and made use of face-valid stimulus materials; it is closely comparable to tests developed for memory assessment in non-human primates that are sensitive to the effects of hippocampal ablation. The present task was found to elicit significant differences in performance between young and non-demented aged subjects, between the non-demented and demented elderly, and between demented subjects in the early and more advanced stages of senile dementia of the Alzheimer type (SDAT). In a discriminant analysis, the visual recognition memory test scores correctly classified 72.6% of the aged subjects and early SDAT patients. No significant difference in task performance was found between SDAT patients and demented patients with a significant cerebrovascular etiological component. Thus, although the task does not appear to be suitable for diagnostic purposes it would be useful for the assessment of treatment effects upon age-related cognitive dysfunction.

Adolescent↗
PubMed1986

Behavioral recovery following bilateral lesions of the nucleus basalis does not occur spontaneously.

Recent studies have shown that rats given bilateral ibotenic acid lesions of the nucleus basalis (NBM) exhibit significant impairments on tasks requiring recent or trial-specific memory. However, despite the persistence of cholinergic deficiencies in the cortical projection area, the memory impairments gradually recover over a period of several months of training. Moreover, in one study, the behavioral recovery on a radial arm maze retention task was shown to generalize to a completely different behavior paradigm (passive avoidance) on which the animals had received no prior experience. The present study was performed to determine the extent to which this generalized recovery of performance on memory tasks is dependent upon extensive post-lesion training. Rats were given ibotenic acid lesions of the NBM and were then passively detained in their home cages for six months. Contrary to animals which had received post-surgical radial arm maze experience, the animals detained in their home cages displayed a significant retention impairment when tested on the passive avoidance task, suggesting that the experience the animals receive is an important factor for whether post-lesion functional recovery occurs. This study also confirms that the loss of cholinergic markers following bilateral, NBM lesions persists for at least several months, or longer.

Animals↗
PubMed1985

Selective memory loss following nucleus basalis lesions: long term behavioral recovery despite persistent cholinergic deficiencies.

Rats were trained for several months to perform a radial arm maze task and then given either sham or ibotenic acid lesions of the nucleus basalis magnocellularis (NBM), the primary cholinergic projection to the neocortex. The lesion produced a profound and apparently selective disturbance in memory for recent events. Further testing revealed that although the memory deficit persisted for several weeks, a gradual but complete recovery eventually occurred. Moreover, when these functionally recovered rats were later tested on a passive avoidance task that is normally sensitive to lesions of the NBM, no deficit was found. Thus, the post-lesion recovery of function generalized to a different memory test, upon which no post-lesion practice had been given. Post-mortem determinations revealed that the lesions caused marked neurodegeneration of the NBM, and decreases in both cortical choline acetyltransferase activity and high affinity choline uptake, but had no effect on density of muscarinic receptors. No evidence of neuronal recovery or neurochemical compensatory changes in the cholinergic system was found in the cortical projection areas, lesion site, or in parallel cholinergic systems terminating in the hippocampus or olfactory bulb. These results support the idea that the cortically-projecting cholinergic cells of the NBM normally play an important role in mediating recent memory. However, they also demonstrate that any simple relationship between the function of this brain region and the mediation of recent memory is unlikely. Finally, the results of this study direct attention toward issues related to the mechanisms involved with the recovery of function, and the extent to which degeneration of this brain area may contribute directly to the severe disturbance of cognitive function associated with certain neurodegenerative diseases (e.g., Alzheimer's, Pick's and Parkinson's disease).

Alzheimer Disease↗
PubMedDate not supplied

Age differences in the vulnerability of facial recognition memory to proactive interference.

A facial recognition memory task was administered to 16 young subjects (age range 18-30) and 28 elderly subjects (age range 63-83). A continuous recognition paradigm was used, in which subjects were instructed to identify the repeated faces in an ongoing series of faces presented on a video monitor screen. A signal detection analysis of the data revealed a mild recognition memory deficit in the elderly, due mainly to an increase in false positives during the second half of the test session. This age-specific increase in late-session false alarms may be a result of increased sensitivity of the aged subjects to proactive interference from previously presented faces. Increasing the length of the delay between the initial and repeat presentation of a face decreased recognition accuracy in both groups, but the young subjects were more sensitive to the delay interval effect than the elderly. Multiple presentations of faces produced a comparable improvement in the recognition accuracy of both young and old subjects. The elderly subjects exhibited a more liberal response bias than the young subjects, indicating that impaired memory task performance of the aged subjects cannot be attributed to a more conservative test-taking strategy.

Adolescent↗