Assessing the global threat from Zika virus.

First discovered in 1947, Zika virus (ZIKV) infection remained a little-known tropical disease until 2015, when its apparent association with a considerable increase in the incidence of microcephaly in Brazil raised alarms worldwide. There is limited information on the key factors that determine the extent of the global threat from ZIKV infection and resulting complications. Here, we review what is known about the epidemiology, natural history, and public health effects of ZIKV infection, the empirical basis for this knowledge, and the critical knowledge gaps that need to be filled

Practice Effects on Story Memory and List Learning Tests in the Neuropsychological Assessment of Older Adults.

Two of the most commonly used methods to assess memory functioning in studies of cognitive aging and dementia are story memory and list learning tests. We hypothesized that the most commonly used story memory test, Wechsler's Logical Memory, would generate more pronounced practice effects than a well validated but less common list learning test, the Neuropsychological Assessment Battery (NAB) List Learning test. Two hundred eighty-seven older adults, ages 51 to 100 at baseline, completed both tests as part of a larger neuropsychological test battery on an annual basis. Up to five years of recall scores from participants who were diagnosed as cognitively normal (n = 96) or with mild cognitive impairment (MCI; n = 72) or Alzheimer's disease (AD; n = 121) at their most recent visit were analyzed with linear mixed effects regression to examine the interaction between the type of test and the number of times exposed to the test. Other variables, including age at baseline, sex, education, race, time (years) since baseline, and clinical diagnosis were also entered as fixed effects predictor variables. The results indicated that both tests produced significant practice effects in controls and MCI participants; in contrast, participants with AD declined or remained stable. However, for the delayed-but not the immediate-recall condition, Logical Memory generated more pronounced practice effects than NAB List Learning (b = 0.16, p < .01 for controls). These differential practice effects were moderated by clinical diagnosis, such that controls and MCI participants-but not participants with AD-improved more on Logical Memory delayed recall than on delayed NAB List Learning delayed recall over five annual assessments. Because the Logical Memory test is ubiquitous in cognitive aging and neurodegenerative disease research, its tendency to produce marked practice effects-especially on the delayed recall condition-suggests a threat to its validity as a measure of new learning, an essential construct for dementia diagnosis

Practice Effects on Story Memory and List Learning Tests in the Neuropsychological Assessment of Older Adults.

Two of the most commonly used methods to assess memory functioning in studies of cognitive aging and dementia are story memory and list learning tests. We hypothesized that the most commonly used story memory test, Wechsler's Logical Memory, would generate more pronounced practice effects than a well validated but less common list learning test, the Neuropsychological Assessment Battery (NAB) List Learning test. Two hundred eighty-seven older adults, ages 51 to 100 at baseline, completed both tests as part of a larger neuropsychological test battery on an annual basis. Up to five years of recall scores from participants who were diagnosed as cognitively normal (n = 96) or with mild cognitive impairment (MCI; n = 72) or Alzheimer's disease (AD; n = 121) at their most recent visit were analyzed with linear mixed effects regression to examine the interaction between the type of test and the number of times exposed to the test. Other variables, including age at baseline, sex, education, race, time (years) since baseline, and clinical diagnosis were also entered as fixed effects predictor variables. The results indicated that both tests produced significant practice effects in controls and MCI participants; in contrast, participants with AD declined or remained stable. However, for the delayed-but not the immediate-recall condition, Logical Memory generated more pronounced practice effects than NAB List Learning (b = 0.16, p &lt; .01 for controls). These differential practice effects were moderated by clinical diagnosis, such that controls and MCI participants-but not participants with AD-improved more on Logical Memory delayed recall than on delayed NAB List Learning delayed recall over five annual assessments. Because the Logical Memory test is ubiquitous in cognitive aging and neurodegenerative disease research, its tendency to produce marked practice effects-especially on the delayed recall condition-suggests a threat to its validity as a measure of new learning, an essential construct for dementia diagnosis

Participant Flow.

<p>Flowchart illustrating application of inclusion and exclusion criteria for the current study.</p

Results of the Linear Mixed Effects Model for Immediate Recall.

<p>Results of the Linear Mixed Effects Model for Immediate Recall.</p

Baseline Demographic Characteristics of the Current Sample.

<p>Baseline Demographic Characteristics of the Current Sample.</p

Clinical Diagnosis by Visit.

<p>Heatmap depicting the clinical diagnosis assigned to each participant at each study visit. The left panel represents participants whose most recent diagnosis was Control. The middle panel represents participants whose most recent diagnosis was MCI. The right panel represents participants whose most recent diagnosis was AD. Colors reflect the diagnosis made at a given visit, which does not always correspond to the most recent diagnosis. Participants' most recent visit may have occurred beyond the 5 visits used in the current study.</p

Results of the Linear Mixed Effects Model for Delayed Recall.

<p>Results of the Linear Mixed Effects Model for Delayed Recall.</p

Delayed Recall Practice Effects.

<p>Standardized test scores on the delayed recall condition as a function of visit number, test, and clinical diagnosis. Error bars represent 95% confidence intervals and account for within-subjects variability.</p

Immediate Recall Practice Effects.

<p>Standardized test scores on the immediate recall condition as a function of visit number, test, and clinical diagnosis. Error bars represent 95% confidence intervals and account for within-subjects variability.</p