Diagnosing the Prodromal State of Alzheimer's Disease

Mild Cognitive Impairment- Amnestic Subtype (MCIa) is a putative prodromal stage of Alzheimer’s Disease (AD) characterized by focal deficits in episodic verbal memory. Less is known about relative deficits in visuospatial learning, although there is ample evidence indicating involvement of the hippocampus in visuospatial learning, as well as hippocampal degeneration in early AD. The aim of this study was to better characterize the components of working memory dysfunction in people with MCIa to increase the ability to reliably diagnose this disease. Fifty-six elderly adults diagnosed with MCIa and 94 healthy elderly completed a hidden maze learning task. Results indicated similar functioning between groups on measures of reasoning, problem solving, and accuracy. However, MCIa subjects were less efficient at learning the hidden path, making more errors per second on average (Cohen’s d= -.78) and requiring a longer time to complete the maze (Cohen’s d=.77). The learning curve between the first two trials was four times as steep for healthy elderly compared to MCIa (slopes = 4.9 vs. 1.24, respectively), indicating that MCIa subjects exhibited relative difficulty in holding and making effective use of an internal spatial map in order to improve performance. Our results suggest that MCIa patients have focal deficits in visuospatial working memory, with relative preservation of functioning on other more global measures of cognitive functioning. This particular pattern of results may be specific to the amnestic variant of MCI.

Regional Integration and Industrial Location in a Landlocked Spatial Economy

Regional integration proposals often require agreements between countries that differ in geographic size, resource endowments, transportation assets, technologies, and product quality. In this asymmetric setting, questions arise about the potential for mutual gains and the distribution of benefits among industries and workers in each country. This paper examines how regional integration between a small landlocked country and a large neighboring country--with a unique port facility that both nations must use to export goods--affects the wage and location decisions of firms, the allocation of labor, the welfare of each country's workers and firms, and aggregate measures of economic welfare in each country and the region. A simulated spatial labor market model is used to explore the economic effects of various stages of regional integration. Beginning with autarky as a benchmark case, we consider two forms of regional integration: partial mobility (mobile labor with geographically restricted firms); and full mobility (mobile labor and firms) with convergence of production technologies and product quality.

Recognizing a Single-Issue Spatial Election

A single-issue spatial election is a voter preference profile derived from an arrangement of candidates and voters on a line, with each voter preferring the nearer of each pair of candidates. We provide a polynomial-time algorithm that determines whether a given preference profile is a single-issue spatial election and, if so, constructs such an election. This result also has preference representation and mechanism design applications.