The Ubiquity of Memory Retrieval Deficits in Patients With Frontal-Striatal Dysfunction
University of California, San Diego, CA 92161, USA. Cognitive and Behavioral Neurology
(Impact Factor: 0.95).
01/2006; 18(4):198-205. DOI: 10.1097/01.wnn.0000192134.53616.39
Previous studies have shown that patients with frontal-striatal dysfunction demonstrate improved performance on tests of recognition memory relative to free recall memory, suggesting deficits in retrieval processes. Not all studies, however, have indicated that all patients with frontal-striatal dysfunction display this profile. In this study, we examined the ubiquity of this "retrieval deficit" profile in a relatively large sample of patients with Parkinson disease (PD) or Huntington disease (HD).
Participants included 150 patients with PD and 65 patients with HD. Patients were classified as demonstrating a retrieval deficit or not based on a comparison of their standardized performances on the Recognition Discriminability and Long-Delay Free Recall indices from the California Verbal Learning Test.
Results indicated that 1) a retrieval deficit was more prevalent in patients with HD than PD, 2) this group difference emerged only in patients with at least a mild level of global cognitive impairment, and 3) even when the profile did emerge more frequently in patients with HD, it was present in only 44% of the patients.
These findings suggest that not all patient groups with frontal-striatal dysfunction display a retrieval deficit profile, but in groups that do (ie, patients with HD), it is more likely to appear in individuals with greater cognitive impairment.
Available from: Eva Pirogovsky Turk
- "Indeed, the retrieval hypothesis has been questioned more recently, since the magnitude of impairment in delayed recall and recognition memory is similar in most nondemented PD patients222324, as we found in PD-woMCI. In prior studies, the absence of a benefit in recognition memory testing relative to free recall was due to increased false positives on recognition testing , presumably owing to FS-based disinhibition. However , recognition memory false positives and cued recall intrusions were not elevated in our PD-woMCI group, nor were these measures related to FS volumes . "
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Changes in episodic memory are common early in Parkinson's disease (PD) and may be a risk factor for future cognitive decline. Although medial temporal lobe (MTL) memory and frontostriatal (FS) executive systems are thought to play different roles in distinct components of episodic memory impairment in PD, no study has investigated whether different aspects of memory functioning are differentially associated with MTL and FS volumes in nondemented patients without mild cognitive impairment (PD-woMCI).
The present study investigated MRI markers of different facets of memory functioning in 48 PD-woMCI patients and 42 controls.
Regional volumes were measured in structures comprising the MTL and FS systems and then correlated with key indices of memory from the California Verbal Learning Test.
In PD-woMCI patients, memory was impaired only for verbal learning, which was not associated with executive, attention/working memory, or visuospatial functioning. Despite an absence of cortical atrophy, smaller right MTL volumes in patients were associated with poorer verbal learning, long delayed free recall, long delayed cued recall, and recognition memory hits and false positives. Smaller right pars triangularis (inferior frontal) volumes were also associated with poorer long delayed cued recall and recognition memory hits. These relationships were not found in controls.
The findings indicate that MTL volumes are sensitive to subtle changes in almost all facets of memory in PD-woMCI, whereas FS volumes are sensitive only to memory performances in cued-testing formats.
Available from: Jannet Kocerha
- "Studies have suggested that cognitive deficits often emerge as the first symptom of disease onset, specifically seen in speech delay in juvenile HD patients . Approximately 44% of HD patients experiencing some general cognitive impairment reportedly struggle with memory retrieval . The psychiatric disorders common to HD include aggression, affective disorders, irritability, obsession-like symptoms and behavioral and personality disorders . "
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ABSTRACT: Huntington's Disease (HD) is a progressive neurodegenerative disorder caused by an expansion in the polyglutamine (polyQ) region of the Huntingtin (HTT) gene. The clinical features of HD are characterized by cognitive, psychological, and motor deficits. Molecular instability, a core component in neurological disease progression, can be comprehensively evaluated through longitudinal transcriptomic profiling. Development of animal models amenable to longitudinal examination enables distinct disease-associated mechanisms to be identified.
Here we report the first longitudinal study of transgenic monkeys with genomic integration of various lengths of the human HTT gene and a range of polyQ repeats. With this unique group of transgenic HD nonhuman primates (HD monkeys), we profiled over 47,000 transcripts from peripheral blood collected over a 2 year timespan from HD monkeys and age-matched wild-type control monkeys.
Messenger RNAs with expression patterns which diverged with disease progression in the HD monkeys considerably facilitated our search for transcripts with diagnostic or therapeutic potential in the blood of human HD patients, opening up a new avenue for clinical investigation.
Available from: Douglas Galasko
- "These results are consistent with recent reports indicating that patients with PD do not always display improved performance on recognition testing compared to other patients with primarily subcortical pathology (Zizak et al., 2005). "
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ABSTRACT: This study compared verbal learning and memory in patients with autopsy-confirmed dementia with Lewy bodies (DLB) and patients with Parkinson's disease with dementia (PDD). A total of 24 DLB patients, 24 PDD patients, and 24 normal comparison participants were administered the California Verbal Learning Test. The three groups were matched on demographic variables, and the two patient groups were matched on the Mattis Dementia Rating Scale. The results indicated that DLB patients recalled less information than PDD patients on all but one recall measure and displayed a more rapid rate of forgetting. In contrast, the PDD patients committed a greater percentage of perseveration errors than the DLB patients. The two groups did not differ in the percentage of recall intrusion errors or any measures of recognition. A discriminant function analysis (DFA) using short-delay cued recall, percentage of perseveration errors, and List B recall differentiated the DLB and PDD groups with 81.3% accuracy. The application of the DFA algorithm to another sample of 42 PDD patients resulted in a 78.6% correct classification rate. The results suggest that, despite equivalent levels of general cognitive impairment, patients with DLB or PDD exhibit a different pattern of verbal learning and memory deficits.
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