Correlations between SPECT regional cerebral blood flow and psychometric testing in patients with Alzheimer's disease

Thirty-nine patients with probable Alzheimer's disease (AD) were studied with [99mTc]HMPAO SPECT and a standardized neuropsychological battery testing intellect, memory, attention, language, motor and praxis functions, and depression. Spearman rank correlations and multivariate regression analyses were performed to correlate quantitative regional perfusion deficits to these tests. Patients were found to have decreased perfusion of left frontal, parietal, and temporal regions relative to right. WAB repetition scores and bilateral temporal flow were significantly correlated (P < 0.01). Correlations between visual memory and bilateral temporal flow and those between Mini-Mental State/ Geriatric Depression Scale scores and bihemispheric flow approached significance. Although in this study regional cerebral blood flow was relatively insensitive to neuroanatomical abnormalities underlying specific cognitive deficits, it may have some specificity for identifying the language disorder in AD.

SPECT findings on psychosis in Alzheimer's disease

OBJECTIVE

This study examined whether psychosis in Alzheimer's disease is associated with cerebral perfusion patterns appreciable by single photon emission computed tomography (SPECT) scans.

METHOD

All cooperative outpatients enrolled in an Alzheimer's disease research center with the diagnosis of probable Alzheimer's disease and a Clinical Dementia Rating of mild or moderate were interviewed with their primary caregivers. Current and past psychiatric functioning was assessed by using the Hamilton Depression Rating Scale, the Structured Clinical Interview for DSM-III-R, and the Behavioral Pathology in Alzheimer's Disease Rating Scale. Patients without premorbid psychosis received SPECT scans, and the scans of the patients with delusions or hallucinations (N = 30) were compared to the scans of patients without these symptoms (N = 16).

RESULTS

The patients with delusions (N = 29) had hypoperfusion of the left frontal lobe in relation to the right frontal lobe. The patients with hallucinations (N = 10) had hypoperfusion in the parietal lobe.

CONCLUSIONS

Psychotic patients with Alzheimer's disease had a pattern of cerebral blood flow deficits significantly different from that of nonpsychotic patients. This suggests that patterns of cerebral dysfunction may be expressed symptomatically as psychosis.

Spinal bone mineral after 5 weeks of bed rest

Patients put at bedrest for medical reasons lose 1-2% of spinal bone mineral per week. Losses of this magnitude during even short-term space flights of a few months would pose a serious limitation and require countermeasures. The spinal bone mineral (L2-L4) was determined in 6 healthy males (precision = 2%) before and after 5 weeks of complete bed rest. Only one individual had a significant loss (3%) and the -0.9% mean change for the 6, was not significant (P = 0.06). The average negative calcium balance during the 5 weeks was 4 g or 0.36% of total body calcium, similar to that reported in other bed-rest studies. Spinal bone loss, however, in healthy bed-rested males is significantly less than reported for bed-rested patients, suggesting that a large loss of spinal bone mineral does not occur during space flight missions lasting 5 weeks or less.

Changes in nuclear magnetic resonance (T2) relaxation of limb tissue with bed rest

Bed rest is used to simulate the effects of weightlessness on human physiology. A spin-echo procedure was used to image the lower leg of 15 normal male volunteers before and after 5 weeks of horizontal bedrest. In addition to noninvasively measuring muscle size changes, accurate T2 images were produced to investigate possible relaxation time changes immediately (2-4 h) and 1-2 days after bed rest. Subcutaneous fat showed no change in T2, bone marrow showed a decrease, and muscle showed no change immediately after bed rest but increased 1-2 days following reambulation.

Bone and muscle atrophy with suspension of the rat

A modification of the Morey tail suspension model was used to determine atrophic responses of rat bone and muscle with 14-90 days unloading of the hindlimbs. Bone uptake of methylene diphosphonate followed a phasic pattern similar to changes in bone formation rate in immobilized dogs and rats. Increased uptake at 60 days (P = 0.01, femur) indicated an increased bone metabolism. Regional densitometry demonstrated a preferential loss of bone mineral in the trabecular mass (P = 0.02) at 30 days and in the cortical shaft by 90 days (P = 0.03). Maximal muscle atrophy occurred within 14-30 days. The gastrocnemius was less severely affected by suspension than by immobilization techniques, whereas the soleus atrophied (by weight) similarly, suggesting that muscle atrophy in the suspension model is distinctly different from immobilization atrophy. One significant response of skeletal muscle to suspension was an altered blood distribution. Muscle blood distribution changes reflect the hypodynamic state of muscle that continues to contract but probably at an altered rate in response to altered functional demands.

High resolution bone mineral densitometry with a gamma camera

A technique is described by which the regional distribution of bone mineral can be determined in bone samples from small animals. The technique employs an Anger camera interfaced to a medical computer. High resolution (less than 1 mm) imaging is possible by producing magnified images of the bone samples. Regional densitometry of femurs from oophorectomised and bone grafted rats demonstrated significant heterogenity of bone mineral loss.

Changes in total body calcium balance with exercise in the rat

The purpose of this study was to evaluate the effect of deconditioning on the total body calcium in rats. Two separate experiments were performed using female Sprague-Dawley rats, 187-266 days of age. Total body calcium was measured in experimental and control rats during and following several weeks of voluntary exercise. The slope from the least-squares fit of total body calcium with time was used to obtain an average calcium balance for each animal during each study period. In both groups the exercised rats had a significantly decreased calcium balance after cessation of exercise, whereas no significant change was seen in nonexercised controls. In both groups, the exercised animals gained calcium at a significantly greater rate than controls. Our findings indicate that while exercised rats may gain calcium at a faster rate compared with nonexercising controls, the rate of gain following cessation of exercise is less than the controls.