A pilot study of the effects of meditation on regional brain metabolism in distressed dementia caregivers.

AIMS: Caregiver distress can affect mood and cognition. Meditation can be used to reduce stress. This pilot study explored whether yogic meditation could change regional cerebral metabolism in distressed caregivers. METHODS: Nine dementia caregivers were randomized to undergo meditation training compared with relaxation for 12 min per day for 8 weeks. Caregivers received neuropsychiatric assessments and brain FDG-PET scans at baseline and postintervention. RESULTS: The groups did not differ on measures of mood, mental and physical health, and burden at baseline and follow-up. When comparing the regional cerebral metabolism between groups, significant differences over time were found in the bilateral cerebellum (p < 0.0005), right inferior lateral anterior temporal (p < 0.0005), right inferior frontal (p = 0.001), left superior frontal (p = 0.001), left associative visual (p = 0.002) and right posterior cingulate (p = 0.002) cortices. CONCLUSION: Meditation practice in distressed caregivers resulted in different patterns of regional cerebral metabolism from relaxation. These pilot results should be replicated in a larger study.

Time-course of effects of external beam radiation on [18F]FDG uptake in healthy tissue and bone marrow.

The utility of PET for monitoring responses to radiation therapy have been complicated by metabolically active processes in surrounding normal tissues. We examined the time-course of [18F]FDG uptake in normal tissues using small animal-dedicated PET during the 2 month period following external beam radiation. Four mice received 12 Gy of external beam radiation, in a single fraction to the left half of the body. Small animal [18F]FDG-PET scans were acquired for each mouse at 0 (pre-radiation), 1, 2, 3, 4, 5, 8, 12, 19, 24, and 38 days following irradiation. [18F]FDG activity in various tissues was compared between irradiated and non-irradiated body halves before, and at each time point after irradiation. Radiation had a significant impact on [18F]FDG uptake in previously healthy tissues, and time-course of effects differed in different types of tissues. For example, liver tissue demonstrated increased uptake, particularly over days 3-12, with the mean left to right uptake ratio increasing 52% over mean baseline values (p < 0.0001). In contrast, femoral bone marrow uptake demonstrated decreased uptake, particularly over days 2-8, with the mean left to right uptake ratio decreasing 26% below mean baseline values (p = 0.0005). Significant effects were also seen in lung and brain tissue. Radiation had diverse effects on [18F]FDG uptake in previously healthy tissues. These kinds of data may help lay groundwork for a systematically acquired database of the time-course of effects of radiation on healthy tissues, useful for animal models of cancer therapy imminently, as well as interspecies extrapolations pertinent to clinical application eventually.

Clinical Value of Neuroimaging in the Diagnosis of Dementia. Sensitivity and Specificity of Regional Cerebral Metabolic and Other Parameters for Early Identification of Alzheimer's Disease.

Dementing illnesses such as Alzheimer's disease (AD) progressively devastate human brain tissue and consequently the health and lives of people afflicted by these disorders. One of the greatest clinical challenges posed by dementia is establishing an approach to ensure its early identification and accurate diagnosis-thus making it possible to treat and, potentially, arrest the development of disease before a substantial amount of brain tissue has been permanently destroyed. The data generated by neuroimaging studies conducted over the past two decades show PET with [(18)F]fluorodeoxyglucose (FDG) to be exceptionally well-suited to meeting this challenge. The regional metabolic patterns imaged with FDG-PET enable sensitive diagnosis of AD, and reveal pathophysiologic alterations even before they lead to symptomatic expression. The accuracy of PET in identifying early AD, and distinguishing it from other etiologies of cognitive impairment, exceeds that of CT, MRI (qualitative or quantitative), and SPECT, as well as that of expert clinical evaluation based on history, physical examination, cognitive testing, and blood laboratory values. Recent developments in instrumentation and radiopharmaceutical distribution have made obtaining scans of cerebral metabolism achievable in routine clinical settings, including most hospitals in which Nuclear Medicine services are provided, for less than the cost of a single year of anticholinesterase therapy or a single month of lost productivity. The need and opportunity are thus present for making a fundamental change in the current approach to evaluating patients for dementia.