Learning capacity in early-stage Alzheimer's disease: The role of feedback during learning on memory performance.

Alzheimer's disease is characterized by a decline in episodic memory and executive functioning, hampering learning ability. Insight into outcome-based learning capacity may be relevant for optimizing the learning potential of these patients. To date, mixed results have been found in studies in which cognitively impaired participants have to learn based on positive and negative outcomes. In this study, we investigated the role of negative and positive feedback on memory performance and participants' ability to adjust their behaviour accordingly in a sample of 23 early-stage AD patients and 23 matched healthy controls. We administered a novel computerized object-location memory task, in which participants were instructed to learn and memorize the locations of different everyday objects following errorless learning (EL) and trial-and-error learning (TEL). A separate probabilistic TEL task was employed in which participants had to learn how to adjust their behaviour based on positive and negative feedback. EL had a beneficial general effect on memory performance for object locations. However, this effect was not larger in early-stage AD patients compared to controls and error frequency during acquisition of object locations was unrelated to later recall performance. No group differences were found on the probabilistic learning task with respect to learning performance over time and based on positive and negative feedback. Although the error monitoring system seems intact in patients with early-stage AD, errors during learning are likely acting as a source of interference causing difficulty in storage or retrieval of object locations.

Accelerated long-term forgetting after TIA or minor stroke: A more sensitive measure for detecting subtle memory dysfunction?

Cognitive changes after minor stroke or TIA have been reported, with studies describing a 'vascular' cognitive profile with spared episodic memory. Still, many patients also report memory complaints. Studies using long-term forgetting paradigms have detected memory impairment after prolonged intervals in contrast to standard delayed testing in other patient groups. This study examined whether accelerated long-term forgetting (ALF) is present in patients with minor stroke or TIA by comparing one-week delayed recall and recognition with the performance of a healthy control group. Results revealed that the patients' performance after one week was worse than the controls, in the absence of an impairment after a short delay. Patients did, however, not report more memory worries than controls. Possibly, reduced effort, attention or mnemonic strategies may contribute to subtle consolidation problems, which go undetected in daily functioning.

Subjective Memory Ability and Long-Term Forgetting in Patients Referred for Neuropsychological Assessment.

It has been suggested that the memory complaints of patients who are not impaired on formal memory tests may reflect accelerated forgetting. We examined this hypothesis by comparing the 1-week delayed recall and recognition test performance of outpatients who were referred for neuropsychological assessment and who had normal memory performance during standard memory assessment with that of a non-patient control group. Both groups performed equally in verbal learning and delayed recall. However, after 1 week, the patients performed worse than controls on both recall and recognition tests. Although subjective memory ability predicted short-term memory function in patients, it did not predict long-term delayed forgetting rates in either the patients or controls. Thus, long-term delayed recall and recognition intervals provided no additional value to explain poor subjective memory ability in the absence of objective memory deficits.

Accelerated forgetting? An evaluation on the use of long-term forgetting rates in patients with memory problems.

The main focus of this review was to evaluate whether long-term forgetting rates (delayed tests, days, to weeks, after initial learning) are more sensitive measures than standard delayed recall measures to detect memory problems in various patient groups. It has been suggested that accelerated forgetting might be characteristic for epilepsy patients, but little research has been performed in other populations. Here, we identified eleven studies in a wide range of brain injured patient groups, whose long-term forgetting patterns were compared to those of healthy controls. Signs of accelerated forgetting were found in three studies. The results of eight studies showed normal forgetting over time for the patient groups. However, most of the studies used only a recognition procedure, after optimizing initial learning. Based on these results, we recommend the use of a combined recall and recognition procedure to examine accelerated forgetting and we discuss the relevance of standard and optimized learning procedures in clinical practice.