Longitudinal fMRI in elderly reveals loss of hippocampal activation with clinical decline

BACKGROUND

Previous cross-sectional fMRI studies in subjects with prodromal Alzheimer disease (AD) have reported variable results, ranging from hypoactivation, similar to patients with AD, to paradoxically increased activation or hyperactivation compared to cognitively normal older individuals. We have hypothesized that subjects in early phases of prodromal AD may experience a period of hippocampal hyperactivation, followed by loss of hippocampal activation as the disease progresses.

METHODS

We studied 51 older individuals without dementia (Clinical Dementia Rating [CDR] at baseline of 0, n = 21, and 0.5, n = 30) with longitudinal clinical and neuropsychological assessments, as well as fMRI during a face-name associative memory paradigm. Whole brain and region-of-interest analyses were applied to the longitudinal fMRI data.

RESULTS

Subjects classified as CDR 0 at baseline showed no difference in fMRI activity over 2 years, whereas those who were CDR 0.5 at baseline demonstrated a decrease in fMRI activity in the right hippocampus (p < 0.001). Dividing the subjects on the basis of their clinical and neuropsychological change over the 2 years, we found that subjects with more rapid decline demonstrated both the highest hippocampal activation at baseline, and the greatest loss of hippocampal activation. These findings remained significant after accounting for age, hippocampal volume, and APOE epsilon4 carrier status.

CONCLUSIONS

Clinical decline is associated with loss of hippocampal activation in older subjects. Longitudinal fMRI provides a reliable indicator of brain activation over time, and may prove useful in identifying functional brain changes associated with cognitive decline on the trajectory toward clinical Alzheimer disease.

Mendelian inheritance in man: diagnoses in the UMLS

Because they deal with many distinct but rare inheritance diseases, geneticists have difficulty translating from their codes to other biomedical coding schemes. The objective of this research was to investigate the potential uses and difficulties of using the UMLS Metathesaurus for genetic diagnoses and to make recommendations to UMLS developers for improvements in UMLS for common genetic disorders. The 110 most common Mendelian Inheritance in Man disorders from the Missouri Genetic Disease Program over the period of one year were translated into MeSH, ICD and SNOMED. The more common diseases are more likely to be mapped than the rarer ones. Diseases with a proven genetic inheritance pattern are more likely to be mapped than those with speculated inheritance patterns. Approximately one third of all diagnoses were not mapped across all three coding schemes in Meta-1.2. The ICD coding scheme was found to be too broad to be meaningful for genetic diagnosis or epidemiological purposes. MeSH and SNOMED need to be made more specific and complete, and all of the new version of SNOMED needs to be included in the Metathesaurus.

The portable Doppler: practical applications in EMS care

The practical application of a new, commercially available, portable Doppler ultrasound device to the operation of a busy city-county emergency department and ambulance service was investigated. An initial evaluation using healthy volunteers confirmed accuracy and reproducibility of the Doppler blood pressure readings comparable to that of auscultatory and palpatory measurement. In selected patients, the Doppler readings correlated well with readings from patients who had intra-arterial lines. When used in several low flow states, such as testing adequacy of cardiopulmonary resuscitation (CPR) and verification of electromechanical dissociation, the Doppler aided the clinical evaluation and treatment in many cases where traditional methods were useless. The Doppler was also helpful in the evaluation of local arterial injury but this unit was not found sensitive enough for venous disease. Finally, the Doppler enhanced the obtaining of vital signs in the noisy environment of our ambulances.