Clinical Utility of the Envelope Task in Mild Cognitive Impairment and Dementia.

OBJECTIVE: Prospective memory (PM) is a cognitive function defined as the ability to perform an intention at an appropriate moment in the future. In the aging population, PM is essential for maintaining independent daily living. Introduced as a simple and quick way to assess PM in clinical settings, the envelope task has to date received very limited empirical and practical interest. METHODS: The present study investigated the task's clinical utility in detecting PM impairment in a sample composed of 49 healthy older adults (OA), 41 patients with Alzheimer's disease, and 64 individuals with amnestic and nonamnestic mild cognitive impairment (MCI) of heterogeneous etiology: 17 of idiopathic nature, 20 presenting an idiopathic rapid-eye movement sleep behaviour disorder, and 27 patients diagnosed with idiopathic Parkinson's disease. RESULTS: The envelope task was highly sensitive and specific in discriminating Alzheimer's disease patients from OA. Although it was specific in distinguishing MCI individuals from OA, its sensitivity was modest, especially in patients presenting a nonamnestic MCI subtype. CONCLUSIONS: Given its high specificity and simple low-cost administration procedure, the envelope task is a promising instrument for clinicians who seek to rapidly assess PM impairment in their daily practice.

Prospective memory in idiopathic REM sleep behavior disorder with or without mild cognitive impairment: A preliminary study.

OBJECTIVE: The ability to execute delayed intentions, known as prospective memory (PM), is crucial to everyday living. PM failures are reported in mild cognitive impairment (MCI) and Parkinson's disease, however, no study to date has investigated PM functioning in individuals at high risk of developing these conditions, precisely those diagnosed with idiopathic REM sleep behavior disorder (iRBD). We aimed to assess PM in iRBD according to patients' cognitive status and to determine the underlying nature of their difficulties. METHOD: Fifty-eight participants, including 20 healthy controls (HC) and 38 polysomnographic-confirmed iRBD patients with (iRBD-MCI = 13) or without (iRBD-nMCI = 25) MCI participated in this study. Following a neuropsychological assessment, PM was evaluated using a self-administered questionnaire (PRMQ), a simple clinical measure (envelope test), and a laboratory cue salience task. RESULTS: No significant group differences were noted on the PRMQ and envelope test. On the PM laboratory task, non-parametric analyses revealed better detection accuracy in HC than both iRBD groups for all high and low salient cues. While iRBD-nMCI and iRBD-MCI patients performed similarly on the high salient condition, the latter showed significant difficulty in detecting low salient cues. Multiple regression analyses revealed executive dysfunction as the best predictor to significantly account for differences in the low salient condition in iRBD. CONCLUSION: PM difficulties in iRBD are most important in patients with MCI (vs without MCI) and may be attributed to a gradual alteration in executive mechanisms. PM impairment could act as a promising indicator of early cognitive dysfunction in iRBD.