Britt Anderson

Clinical Interview Assessment of Financial Capacity in Older Adults with Mild Cognitive Impairment and Alzheimer's Disease

OBJECTIVES: To investigate financial capacity in patients with mild cognitive impairment (MCI) and Alzheimers disease (AD) using a clinician interview approach.

Declining Financial Capacity in Patients With Mild Alzheimer Disease: A One-Year Longitudinal Study

OBJECTIVE The objective of this study was to investigate change over time in financial abilities in patients with mild Alzheimer disease (AD). METHODS The authors conducted a prospective 1-year longitudinal study at a large southern U.S. metropolitan-area medical school university. Participants included healthy older adults (N=63) and patients with mild AD (N=55). The authors conducted a standardized performance measure of financial capacity. Performance was assessed on 18 financial tasks, nine domains of financial activity, and overall financial capacity. Capacity outcomes classifications (capable, marginally capable, or incapable) for domains and overall performance were made using cut scores referenced to comparison group performance. RESULTS At baseline, patients with mild AD performed significantly below healthy older adults on 16 of 18 tasks, on all nine domains, and on overall financial capacity. At one-year follow up, comparison group performance was stable on all variables. In contrast, patients with mild AD showed substantial declines in overall financial capacity, on eight of nine domains, and on 12 of 18 tasks. Similarly, the proportion of the mild AD group classified as marginally capable and incapable increased substantially over one year for the two overall scores and for five financial domains. CONCLUSIONS Financial capacity is already substantially impaired in patients with mild AD at baseline and undergoes rapid additional decline over one year. Relative to the comparison group, overall financial capacity performance in the AD group declined 10%, from approximately 80% of the comparison group performance at baseline to 70% at follow up. Financial skills showed differential rates of decline on both simple and complex tasks. Of clinical and public policy interest was the declining judgment of patients with mild AD regarding simple fraud schemes. The study supports the importance of prompt financial supervision and planning for patients newly diagnosed with AD.

Biases in Attentional Orientation and Magnitude Estimation Explain Crossover: Neglect is a Disorder of Both

Crossover refers to a pattern of performance on the line bisection test in which short lines are bisected on the side opposite the true center of long lines. Although most patients with spatial neglect demonstrate crossover, contemporary theories of neglect cannot explain it. In contrast, we show that blending the psychophysical construct of magnitude estimation with neglect theory not only explains crossover, but also addresses a quantitative feature of neglect that is independent of spatial deficits. We report a prospective validation study of the orientation/estimation hypothesis of crossover. Forty subjects (17 patients with and without neglect following unilateral brain injury and 23 normal controls) completed four experiments that examined crossover using line bisection, line bisection with cueing, and reproducing line lengths from both memory and a standard. Replicating earlier findings, all except one subject group exhibited crossover on the standard line bisection test, all groups showed a spontaneous preference to orient attention to one end of the lines, and all groups overestimated the length of short lines and underestimated long lines. Biases in attentional orientation and magnitude estimation are exaggerated in patients with neglect. The truly novel finding of this study occurred when, after removing the line from the bisection task, the direction of crossover was completely reversed in all subject groups depending on where attention was oriented. These findings are consistent with our hypothesis of crossover: (1) crossover is a normal component of performance on line bisection; (2) crossover results from the interplay of biases in attentional orientation and magnitude estimation; and (3) attentional orientation predicts the direction of crossover, whereas a disorder of magnitude estimation, not previously emphasized in neglect, accounts for the quantitative changes in length estimation that make crossover more obvious in neglect subjects. Paradoxically, we observed that the traditional line bisection test is suboptimal for exploring crossover because lines elicit spontaneous orientation responses from subjects that confound experimental manipulations of attention. We conclude that attentional orientation and magnitude estimation are necessary and sufficient to explain crossover and that bias in magnitude estimation is a core component of neglect.

Effects of temporal context and temporal expectancy on neural activity in inferior temporal cortex.

Timing is critical. The same event can mean different things at different times and some events are more likely to occur at one time than another. We used a cued visual classification task to evaluate how changes in temporal context affect neural responses in inferior temporal cortex, an extrastriate visual area known to be involved in object processing. On each trial a first image cued a temporal delay before a second target image appeared. The animals task was to classify the second image by pressing one of two buttons previously associated with that target. All images were used as both cues and targets. Whether an image cued a delay time or signaled a button press depended entirely upon whether it was the first or second picture in a trial. This paradigm allowed us to compare inferior temporal cortex neural activity to the same image subdivided by temporal context and expectation. Neuronal spiking was more robust and visually evoked local field potentials (LFPs) larger for target presentations than for cue presentations. On invalidly cued trials, when targets appeared unexpectedly early, the magnitude of the evoked LFP was reduced and delayed and neuronal spiking was attenuated. Spike field coherence increased in the beta-gamma frequency range for expected targets. In conclusion, different neural responses in higher order ventral visual cortex may occur for the same visual image based on manipulations of temporal attention.

Joint decoding of visual stimuli by IT neurons’ spike counts is not improved by simultaneous recording

Information about visual stimuli such as objects and faces is represented across populations of neurons of the inferior temporal cortex. Does recording from inferotemporal neurons simultaneously tell you more than recording from them sequentially? Equivalently, are neurons conditionally independent given a stimulus? To evaluate these issues, we recorded from two monkeys during a passive viewing task. Multiple neurons were simultaneously recorded on separate electrodes. From spike counts in 50-ms windows, we computed the mutual information between counts and images for each neuron individually and jointly with other simultaneously recorded neurons. To determine the significance of these values, we shuffled the stimulus labels (to test if there was significant information) or shuffled responses across trials involving the same image (to see if there was synergistic coding). We recorded from 127 pairs of neurons where each neuron individually was visually responsive. Depending on the time window, we found up to ∼ 90% of these pairs showed significant information about the visual stimulus. Shuffling across trials failed to show evidence for synergistic coding. In summary, if you were given two of our neuronal responses and asked to guess the stimulus which produced them you could not, in principle, do better with two simultaneously recorded spike counts than with any two spike counts selected randomly from trials of the same type.

XOR style tasks for testing visual object processing in monkeys

Using visually complex stimuli, three monkeys learned visual exclusive-or (XOR) tasks that required detecting two way visual feature conjunctions. Monkeys with passive exposure to the test images, or prior experience, were quicker to acquire an XOR style task. Training on each pairwise comparison of the stimuli to be used in an XOR task provided nearly complete transfer when stimuli became intermingled in the full XOR task. Task mastery took longer, accuracy was lower, and response times were slower for conjunction stimuli. Rotating features of the XOR stimuli did not adversely effect recognition speed or accuracy.

Neglect as a disorder of prior probability

Subjects with spatial neglect are slower and more variable in detecting visual targets, especially on the side opposite their brain injuries. These deficits can be seen by plotting cumulative distribution functions (CDF) of response times (RT). I demonstrate that dividing RTs by their means normalizes the RT CDFs of neglect subjects. The motivation for this transformation comes from Carpenters LATER model [Carpenter, R. H. S., & Williams, M. L. L. (1995). Neural computation of log likelihood in control of saccadic eye movements. Nature, 377, 59-62]. The most direct interpretation of this result is that some symptoms of neglect reflect abnormal estimates of stimulus prior probability.

Neural transplants are grey matters

The lesion and transplantation data cited by Sinden et al., when considered in tandem, seem to harbor an internal inconsistency, raising questions of false localization of function. The extrapolation of such data to cognitive impairment and potential treatment strategies in Alzheimers disease is problematic. Patients with focal basal forebrain lesions (e.g., anterior communicating artery aneurysm rupture) might be a more appropriate target population.