Mouse Alzheimer Disease
Emilien and colleagues (SEE ARTICLE) provide a superb review of transgenic mouse models with human gene mutations that cause Alzheimer disease. Specific strategies for using these elegant experimental approaches are presented and provide the clinician with insights into the molecular mechanisms involved in Alzheimer disease.
Disconnections After Callosotomy
Funnell and colleagues (SEE ARTICLE) are pioneers and leaders in the field of split-brain patient studies and review the current state of knowledge comparing patients with callosotomy with localized lesions involving different portions of the corpus callosum. Their review provides a succinct analysis of clinical phenomena in patients with these lesions.
Clinical Criteria for Vascular Dementia
Chui and colleagues (SEE ARTICLE) describe specific clinical criteria for diagnosing vascular dementia. Criteria must be specific and defined, and the authors review and clarify this challenging literature. The subject is put into perspective in an accompanying editorial by Bowler and Hachinski (SEE ARTICLE) . Their comments are of great interest in view of their pioneering contributions to our understanding of vascular dementia in its several forms.
Walking After Pallidotomy
Siegel and Verhagen (SEE ARTICLE) provide an admirable study of patients with Parkinson disease who are treated with pallidotomy and their subsequent gait improvement. This is a model of clinical research and will be widely cited.
Positron Emission Tomographic Scanning in Early Parkinson Disease
Schwarz and colleagues (SEE ARTICLE) explore the specific binding of ligands to dopamine transporters as a tool to detect the early loss of nigra striatal neurons in patients with Parkinson disease. They find early and specific changes with definite clinical correlations that will be useful in following the natural history of the disease.
Angiotensin-
Converting Enzyme and Alzheimer Disease
Farrer et al (SEE ARTICLE) have studied the interrelationships between apolipoprotein E and angiotensin-converting enzyme genotypes as risk factors for late-onset Alzheimer disease. Angiotensin-converting enzyme does present a restricted risk factor that will be the subject of intense future investigations.
Myophosphorylase Revisited
Fernández et al (SEE ARTICLE) describe a novel missense mutation (W797R) in the myophosphorylase gene in patients with McArdle disease. It is a unique mutation among Spanish patients and needs to be included in future gene analyses.
Intracranial Volume and Alzheimer Disease
Jenkins and colleagues (SEE ARTICLE) have assessed total intracranial volume as an independent predictive factor for Alzheimer disease. Premorbid brain size does not differ between patients with familial and sporadic Alzheimer disease and controls and does not delay disease onset. These data provide interesting evidence against the cerebral-reserve hypothesis and clearly will be the subject of future debates.
Separating Pick Disease From Alzheimer Disease
Binetti and colleagues (SEE ARTICLE) conclude that there is a characteristic cognitive profile in the course of dementia in Pick disease compared with Alzheimer disease, but specific cognitive test performance does not clearly distinguish these two entities. Interesting data are provided that are of considerable clinical value.
Estrogen Receptor Polymorphisms and Alzheimer Disease
Maruyama and colleagues (SEE ARTICLE) report no association between estrogen receptor 
gene polymorphisms and Alzheimer disease. These data do not support a selective estrogen receptor response in some patients but serve to focus current discussion concerning estrogen protection against Alzheimer disease.
Very Late Friedreich Ataxia With Very Large GAA Repeats: A Paradox
Bidichandani and colleagues (SEE ARTICLE) describe a unique case of very late Friedreich ataxia with large GAA triplet repeat expansions in both X25 genes that were estimated to contain 835 and 1200 repeats, respectively. This is the first instance of a patient with Friedreich disease with over 800 GAA repeats in both alleles who presented with late onset and a generally milder disease than that seen in typical patients. Clearly, other genetic and environmental factors can modify disease severity that thus far have escaped attention.
