Herman Buschke

Evaluating storage, retention, and retrieval in disordered memory and learning

Two simple methods that are clinically useful for analyzing impaired memory and learning are selective reminding or restricted reminding. These new methods provide simultaneous analysis of storage, retention, and retrieval during verbal learning because they let the patient show learning by spontaneous retrieval without csnfounding by continual presentation. Because selective reminding and restricted reminding let the patient show consistent retrieval without any further presentation, they also distinguish list learning from item learning, so that impaired memory and learning can be analyzed further in terms of two stages of learning (item and list).

Selective reminding for analysis of memory and learning

A new and more appropriate paradigm for verbal learning is described and illustrated. Reminding a subject only of items not recalled on the immediately preceding trial, instead of presenting all items on each trial, shows retrieval from long-term storage when items are retrieved again without further presentation. This permits simultaneous analysis of long-term storage (LTS), retrieval from long-term storage (LTR), and recall from short-term storage (STR). Evaluating LTR in terms of items consistently retrieved on all subsequent trials (without further presentation) differentiates LTR into random and organized LTR, and also provides a measure of list learning for comparison with item learning. To illustrate the use of selective reminding for investigation of retrieval alone, an example is also presented of reminding only until first recall.

Genuine memory deficits in dementia

Controlled learning with effective cued recall is needed to distinguish between genuine memory deficits due to impairment of specific memory processes and apparent memory deficits due to impairment of other cognitive processes, such as attention, that can limit memory. Effective cued recall is needed for accurate measurement of memory in the elderly because cued recall reveals learning not shown by free recall. When a search procedure was used to control processing for effective encoding and cued recall, nondemented elderly adults recalled all or nearly all 16 items on each trial. Decreased recall by demented patients even after they carried out the same effective processing showed genuine memory impairment that was not due to other cognitive deficits. Cued recall was better than either free recall or recognition in discriminating elderly persons with dementia from those without dementia and by itself accounted for 75 % of the variation in dementia status. Cued recall was especially useful for identifying...

Screening for dementia by memory testing

Enhanced cued recall provides a simple and clinically useful memory test for identifying dementia in the elderly. Because this test induces semantic processing and coordinates encoding and retrieval for maximum recall, genuine memory deficits due to impairment of specific memory processes can be distinguished from apparent memory deficits due to use of inefficient strategies or impairment of other cognitive processes. Since genuine memory deficits in the elderly are usually associated with dementia, their identification is highly predictive of clinical dementia. The present study validates the use of enhanced cued recall as a screening test for dementia in 70 aged subjects. All but one person with a pure amnesia were correctly classified. Enhanced cued recall correctly classified 97% of the 120 subjects in this and the previous study. Enhanced cued recall shows learning not revealed by free recall, providing more accurate measurement of memory, and distinguishes demented from nondemented elderly more accurately than either free recall or recognition.

Screening for dementia with the Memory Impairment Screen

Objectives: To validate a sensitive and specific screening test for AD and other dementias, assess its reliability and discriminative validity, and present normative data for its use in various applied settings. Background: To improve discrimination in screening for AD and dementia, we developed the Memory Impairment Screen (MIS), a 4-minute, four-item, delayed free- and cued-recall test of memory impairment. The MIS uses controlled learning to ensure attention, induce specific semantic processing, and optimize encoding specificity to improve detection of dementia. Methods: Equivalent forms of the MIS were given at the beginning and end of the testing session to assess alternate forms reliability. Discriminative validity was assessed in a criterion sample of 483 aged individuals, 50 of whom had dementia according to Diagnostic and Statistical Manual of Mental Disorders (3rd ed., revised) criteria. Results: The MIS had good alternate forms reliability, high construct validity for memory impairment, and good discriminative validity in terms of sensitivity, specificity, and positive predictive value. We present normative data for use in settings with different base rates (prevalences) of AD and dementia. Conclusion: The MIS provides efficient, reliable, and valid screening for AD and other dementias.

Cued recall in Amnesia

Use of a search procedure to control processing during learning results in apparently normal cued recall by some amnesic patients with impaired free-recall learning. This suggests that their ability to encode and retrieve may be relatively intact when they are induced to carry out effective processing during learning. When processing is controlled during learning, cued recall should be useful for neuropsychological evaluation of residual learning and memory capacity.

Validity of divided attention tasks in predicting falls in older individuals: A preliminary study

OBJECTIVES: Although cognitive impairment is known to be a major risk factor for falls in older individuals, the role of cognitive tests in predicting falls has not been established. Limited attentional resources may increase the risk for falls in older individuals. We examined the reliability and validity of divided attention tasks, walking while talking (WWT), in predicting falls.

Leisure activities and the risk of amnestic mild cognitive impairment in the elderly

Objective: To study the influence of leisure activity participation on risk of development of amnestic mild cognitive impairment (aMCI). Methods: The authors examined the relationship between baseline level of participation in leisure activities and risk of aMCI in a prospective cohort of 437 community-residing subjects older than 75 years, initially free of dementia or aMCI, using Cox analysis adjusted for age, sex, education, and chronic illnesses. The authors derived Cognitive and Physical Activity Scales based on frequency of participation in individual activities. Results: Over a median follow-up of 5.6 years, 58 subjects had development of aMCI. A one-point increase on the Cognitive (hazard ratio [HR] 0.95, 95% CI 0.91 to 0.99) but not Physical Activities Scale (HR 0.97, 95% CI 0.93 to 1.01) was associated with lower risk of aMCI. Subjects with Cognitive Activity scores in the highest (HR 0.46, 95% CI 0.24 to 0.91) and middle thirds (HR 0.52, 95% CI 0.29 to 0.96) had a lower risk of aMCI compared with subjects in the lowest third. The association persisted even after excluding subjects who converted to dementia within 2 years of meeting criteria for aMCI. Conclusions: Cognitive activity participation is associated with lower risk of development of amnestic mild cognitive impairment, even after excluding individuals at early stages of dementia.

Memory and mental status correlates of modified Braak staging

We assessed the relationships of performance on memory and mental status tests and neuropathologic stage of Alzheimers disease as defined by Braak and Braak in 29 patients from a prospective clinicopathologic series. We predicted that memory changes would occur at an earlier Braak stage than mental status changes. Staging was accomplished by matching the topographic distribution of neurofibrillary lesions detected with tau immunocytochemistry to the best fitting diagram published by Braak and Braak. Higher Braak stages were associated with decrements in performance on both memory and mental status tests. As predicted, memory performance declined from stages II to III and mental status did not decline until stages III to IV. The association between memory and Braak stage was unchanged after adjusting for neocortical senile plaques, whereas adjustments for Braak stage eliminated the association between cognitive functioning and amyloid burden. We conclude that Braak staging provides a useful summary of Alzheimers disease neuropathology, which is associated with both memory and mental status performance.

Diagnosis of early dementia by the Double Memory Test: Encoding specificity improves diagnostic sensitivity and specificity

Objective To compare the Double Memory Test (DMT) with standard memory tests in the diagnosis of early dementia. Background Diagnosis of dementia requires memory impairment, but few memory tests coordinate acquisition and retrieval to optimize encoding specificity for high sensitivity and specificity. The DMT was developed to improve early diagnosis. Design We compared the discriminative validity of the DMT, Paired Associates (PA), and Logical Memory (LM) memory tests in a nested case-control study of 30 cases of early dementia and 90 controls matched for age, education, and sex. Methods The DMT includes memory tests with (CCR) and without (ICR) encoding specificity. Both tests use category cues to elicit retrieval, but CCR optimizes encoding specificity because the same cues are used for acquisition and retrieval. ICR does not because category cues are used only for retrieval. We used conditional logistic regression to estimate diagnostic sensitivity and specificity. Results The median BIMC of dementia cases was 10, indicating mild dementia. CCR had much higher sensitivity (93%) and specificity (99%) than ICR (53%, 94%), PA (68%, 91%), and LM (48%, 92%). CCR had the greatest advantage in the mildest cases. Conclusions CCR has substantially higher sensitivity and specificity for diagnosis of early dementia than memory tests that do not coordinate acquisition and retrieval. Superior discrimination by CCR is due to an encoding specificity deficit in dementia that increases the difference in recall by cases and controls. CCR is an efficient test with excellent discriminative validity that should facilitate diagnosis of early dementia.