Eva Pirogovsky

Visual Object Pattern Separation Deficits in Nondemented Older Adults.

Young and nondemented older adults were tested on a continuous recognition memory task requiring visual pattern separation. During the task, some objects were repeated across trials and some objects, referred to as lures, were presented that were similar to previously presented objects. The lures resulted in increased interference and an increased need for pattern separation. For each object, the participant was asked to indicate whether (1) this was the first time the object was seen (new), (2) the object was seen previously (old), or (3) the object was similar to a previous object (similar). Older adults were able to correctly identify objects as old or new as well as young adults; however, older adults were impaired when identifying lures as similar. Therefore, pattern separation may be less efficient in older adults resulting in poorer recognition memory performance when interference is increased.

Prospective Memory Deficits are Associated with Poorer Everyday Functioning in Parkinson's Disease

Although individuals with Parkinsons disease (PD) evidence moderate deficits in prospective memory (PM), it is not known whether PM deficits confer an increased risk of poorer everyday functioning. In the current study, 33 individuals with PD and 26 demographically similar normal controls (NC) were administered performance-based and self-report measures of PM and everyday functioning, including medication and financial management. As compared to NC, PD participants demonstrated significantly lower scores on performance-based measures of PM and financial capacity, worse performance at a trend level on performance-based medication management and endorsed significantly greater self-reported declines in PM and instrumental activities of daily living (iADLs). In the PD sample, the laboratory measure of PM significantly correlated with performance-based measures of financial capacity and medication management and a self-report measure of medication management. Self-reported PM failures significantly correlated with perceived declines in iADLs, worse medication management, and poorer health-related quality of life. Although future studies are needed to examine the incremental ecological validity of PM in PD, findings from this study extend prior research by providing preliminary evidence that PM impairment may play a significant role in a range of critical everyday functions in PD.

Visual object pattern separation varies in older adults.

Young and nondemented older adults completed a visual object continuous recognition memory task in which some stimuli (lures) were similar but not identical to previously presented objects. The lures were hypothesized to result in increased interference and increased pattern separation demand. To examine variability in object pattern separation deficits, older adults were divided into impaired and unimpaired groups based on performance on a standardized serial list-learning task. Impaired older adults showed intact recognition memory, but were impaired relative to young and unimpaired older adults when identifying similar lure stimuli, demonstrating that object pattern separation varies in older adults.

Impairments in source memory for olfactory and visual stimuli in preclinical and clinical stages of Huntington's disease

Individuals in preclinical and clinical stages of Huntingtons disease (HD) demonstrate impairments in olfactory functioning. In addition, HD patients are impaired in source memory for verbal stimuli. A task combining both source and odor memory may be particularly sensitive to early changes in HD. The present study examined source and item memory for olfactory and visual stimuli in 10 individuals with HD, 10 asymptomatic HD gene carriers, 8 nongene carriers who had a parent with HD, and 20 normal controls. During the study phase, a male and a female experimenter (sources) presented odors and objects to the participant in an alternating sequence. To assess item memory, a stimulus from the study phase (target) and a novel stimulus (distractor) were presented, and the participant was asked to choose the target. To assess source memory, the experimenter presented a stimulus and asked whether the male or female experimenter had previously presented the stimulus. Results indicate that source memory for both visual and olfactory stimuli was impaired in HD patients compared to normal controls. In asymptomatic gene carriers, however, source memory for olfactory stimuli, but not visual stimuli, was more impaired than in nongene carriers and normal controls. Furthermore, gene carriers and HD patients showed a similar degree of impairment in source memory for olfactory stimuli. The only significant impairment found in item memory was for olfactory stimuli in HD patients. These results suggest that source memory for olfactory stimuli may be particularly sensitive to neuropathological changes in preclinical stages of HD.

The Effect of Interference on Temporal Order Memory for Random and Fixed Sequences in Nondemented Older Adults.

Two experiments tested the effect of temporal interference on order memory for fixed and random sequences in young adults and nondemented older adults. The results demonstrate that temporal order memory for fixed and random sequences is impaired in nondemented older adults, particularly when temporal interference is high. However, temporal order memory for fixed sequences is comparable between older adults and young adults when temporal interference is minimized. The results suggest that temporal order memory is less efficient and more susceptible to interference in older adults, possibly due to impaired temporal pattern separation.

Instrumental activities of daily living are impaired in Parkinson’s disease patients with mild cognitive impairment.

OBJECTIVE Although it is well known that Parkinsons disease (PD) with dementia results in functional decline, little is known about the impact of mild cognitive impairment in PD (PD-MCI) on day-to-day functioning. METHOD Forty-one individuals with PD-MCI, 56 PD patients with normal cognition (PD-NC), and 47 healthy older adults were administered two performance-based measures of instrumental activities of daily living (IADLs) that evaluated medication and financial management. Informants of the PD patients were also administered an IADL questionnaire. RESULTS There were no significant differences between PD-NC and healthy older adults on the performance-based measures of medication and financial management. However, PD-MCI patients demonstrated significantly lower scores on the performance-based measures of medication and financial management compared with healthy older adults. PD-MCI patients were also impaired compared with PD-NC patients on performance-based medication management, but no difference between these groups was observed for ability to manage finances. Performance-based financial and medication management did not correlate with scores on neuropsychological measures in PD-MCI patients. PD-MCI and PD-NC patients showed comparable scores on the informant-based IADL questionnaire. CONCLUSIONS Performance-based measures of IADLs, particularly medication management ability, are sensitive to subtle functional declines in PD-MCI. Although impairment in performance-based measures is associated with cognitive status in PD, IADLs may be a separate domain of functioning from cognitive functioning in PD-MCI as these measures did not correlate with performance on the neuropsychological measures. Overall, performance-based assessment of IADLs may add to the clinical evaluation of PD-MCI.

The utility of the Mattis Dementia Rating Scale in Parkinson's disease mild cognitive impairment

BACKGROUND The Movement Disorders Society (MDS) recently proposed guidelines for diagnosis of mild cognitive impairment in Parkinsons disease (PD-MCI) that includes two assessment levels: abbreviated (Level I) and comprehensive (Level II). The aim of this study was to determine the utility of the Mattis Dementia Rating Scale (MDRS), a recommended Level I test, for detecting Level II PD-MCI diagnosis. METHODS The study sample included 30 patients diagnosed with PD-MCI based on Level II MDS criteria and 68 PD patients with normal cognition (PD-NC). Receiver operator curve (ROC) analyses were generated to measure the sensitivity and specificity of various MDRS cutoff scores. To examine the utility of the MDRS as a screening tool, the optimal cutoff point was defined as the lowest value providing ≥80% sensitivity. For use of the MDRS as a diagnostic tool, the optimal cutoff point was defined as the highest value providing ≥80% specificity. RESULTS ROC analyses showed that the optimal MDRS cutoff score for screening purposes and diagnostic purposes were ≤140 and ≤137, respectively. However, an examination of sensitivity/specificity values for the screening cutoff scores suggested that a total score of ≤139 for screening purposes yielded a better balance between sensitivity (77%) and specificity (65%). CONCLUSIONS In a clinical setting, in which detection of PD-MCI may be important, a total MDRS score of ≤139 can be used to detect PD-MCI. In research and other settings in which diagnostic certainty is more important, a score of ≤137 may be more useful.

Temporal order memory deficits prior to clinical diagnosis in Huntington’s disease

The current study examined temporal order memory in preclinical Huntingtons disease (pre-HD). Participants were separated into less than 5 years (pre-HD near) and more than 5 years (pre-HD far) from estimated age of clinical diagnosis. Participants completed a temporal order memory task on a computerized radial eight-arm maze. On the study phase of each trial, participants viewed a random sequence of circles appearing one at a time at the end of each arm. On the choice phase, participants viewed two circles at the end of the study phase arms and chose the circle occurring earliest in the sequence. The task involved manipulations of the temporal lag, defined as the number of arms occurring in the sample phase sequence between the two choice phase arms. Research suggests that there is more interference for temporally proximal stimuli relative to temporally distal stimuli. There were no significant differences between the pre-HD far group and controls on the temporal order memory task. The pre-HD near group demonstrated significant impairments relative to the other groups on closer temporal lags, but were normal on the furthest temporal lag. Therefore, temporal order memory declines with increased temporal interference in pre-HD close to estimated diagnosis of HD.

Age-Related Changes in Contextual Associative Learning

The hippocampus plays a critical role in processing contextual information. Although age-related changes in the hippocampus are well documented in humans, nonhuman primates, and rodents, few studies have examined contextual learning deficits in old rats. The present study investigated age-related differences in contextual associative learning in young (6 mo) and old (24 mo) rats using olfactory stimuli. Stimuli consisted of common odors mixed in sand and placed in clear plastic cups. Testing was conducted in two boxes that represented two different contexts (Context 1 and Context 2). The contexts varied based on environmental features of the box such as color (black vs. white), visual cues on the walls of the box, and flooring texture. Each rat was simultaneously presented with two cups, one filled with Odor A and one filled with Odor B in each context. In Context 1, the rat received a food reward for digging in the cup containing Odor A, but did not receive a food reward for digging in the cup containing Odor B. In Context 2, the rat was rewarded for digging in the cup containing Odor B, but did receive a reward for digging in the cup containing Odor A. Therefore, the rat learned to associate Context 1 with Odor A and Context 2 with Odor B. The rat was tested for eight days using the same odor problem throughout all days of testing. The results showed no significant difference between young and old rats on the first two days of testing; however, young rats significantly outperformed old rats on Day 3. Young rats continued to maintain superior performance compared to old rats on Days 4-8. The results suggest that aging results in functional impairments in brain regions that support memory for associations between specific cues and their respective context.

Differential Effects of Normal Aging on Memory for Odor-Place and Object-Place Associations

Odor-place and object-place associative memory were compared in healthy older (over the age of 65) and young (18 to 25 years of age) adults. Twelve spatial locations were defined on a tabletop board. Either six odors or six objects were presented one at a time and each was paired with a location on the board. The participant then was presented with each stimulus individually and asked to place it in its paired location. Older adults showed impaired odor-place associative memory but unimpaired object-place memory compared to young adults. Item recognition memory for the individual stimuli or locations used on the associative memory task was similar in both groups. The results suggest that odor-place associative memory is particularly affected by age-related brain changes.