Regional cerebral blood flow and depersonalization after tetrahydrocannabinol administration.

OBJECTIVE: The aim of this study was to examine the relationship between depersonalization induced by tetrahydrocannabinol (THC), and regional brain activation. METHOD: Cerebral blood flow (CBF) was measured by means of positron emission tomography (PET) in 59 normal right-handed volunteers before and following intravenous infusions of THC. RESULTS: After THC, CBF showed a global increase which was more marked in the right hemisphere, frontal lobes and anterior cingulate. CONCLUSION: Regression analyses showed positive correlations between the right frontal and anterior cingulate and depersonalization.

Cerebellar activity and disturbed time sense after THC.

Because marijuana continues to be the most commonly used illicit drug, its effects on the brain function are of major interest. We utilized positron emission tomography (PET) and magnetic resonance imaging (MRI) to study the effects of delta-9-tetrahydrocannabinol (THC) infusion on brain blood flow and its behavioral correlates in 46 volunteers. Consistent with previous reports, there was a significant increase in cortical and cerebellar blood flow following THC, but not all subjects showed this effect. Those who showed a decrease in cerebellar CBF also had a significant alteration in time sense. The relationship between decreased cerebellar flow and impaired time sense is of interest because the cerebellum has been linked to an internal timing system.

Intracranial and extracranial blood flow during acute anxiety.

While large numbers of studies are available on anxiety and cerebral blood flow (CBF), little is known about their relationship to extracranial (forehead) flow. The participants were 24 generalized anxiety disorder (GAD) patients and 26 normal volunteers. A randomized, between groups, repeated measures design was used to evaluate changes in cerebral blood flow. Measurements of CBF, forehead skin perfusion and ratings of anxiety and physiologic indices were made under resting conditions and during anxiety induction with epinephrine or saline infusions, given under double-blind conditions while subjects inhaled room air or 5% CO2. These subjects were divided into three groups; those with decreased anxiety, those with mild anxiety, and those with more severe anxiety increase. Subjects with severe anxiety showed least hypercarbic CBF increase (indicating cerebral vasoconstriction) and maximal increase in forehead skin perfusion. Those with minimal anxiety had most hypercarbic cerebral vasodilation and least increase in forehead skin perfusion. Forehead skin perfusion correlated positively with anxiety levels, and negatively with hypercarbic cerebral vasodilation. In animals, sympathetic activation limits hypercapnic cerebral vasodilation. Thus, the restricted hypercapnic cerebral vasodilation during severe anxiety may be mediated through cervical sympathetic fibers which innervate cerebral vessels.

Effect of nitrous oxide on cerebral blood velocity while reclining and standing.

Cerebral blood velocity (CBV) (measured with transcranial Doppler, TCD) and other physiological and rating scale indices were measured before, during, and after inhaling a mixture of 40% nitrous oxide/oxygen and 40% nitrogen/oxygen, given during two separate visits in 7 normal male volunteers. During nitrous oxide/oxygen but not nitrogen/oxygen inhalation, CBV and euphoria increased significantly with minimal changes in other physiological indices except an increase in pulse rate after nitrous oxide/oxygen. In another 7 male volunteers, similar measurements were obtained while lying down and standing up during nitrous oxide/oxygen mixture and nitrogen/oxygen mixture inhalations, given during two separate visits. Nitrous oxide/oxygen inhalation produced significant CBV increase, which showed nonsignificant decrease of no clinical significance during standing up. There were no significant postural changes in blood pressure. Standing up during nitrous oxide/oxygen inhalation was associated with significant though mild dizziness.

Cerebral vasodilation and vasoconstriction associated with acute anxiety.

A randomized, between-groups, repeated measures design was used to evaluate changes in cerebral blood flow (CBF), rating scales, and physiologic indices under resting conditions, during 5% CO2 inhalation in combination with epinephrine or saline infusions, in generalized anxiety disorder patients and controls. Subjects were divided into those with decreased anxiety and mild and more severe anxiety increase. The first group was found to have most pronounced CBF increase during CO2 inhalation, with the second group showing less marked increase, and the last group the least increase. In animals, sympathetic activation limits hypercapnic cerebral vasodilation. Thus, the restricted hypercapnic cerebral vasodilation during severe anxiety may be mediated through cervical sympathetic fibers, which innervate cerebral vessels.

Marijuana intoxication and brain activation in marijuana smokers.

OBJECTIVE AND METHOD: The acute effects of delta9 tetrahydrocannabinol (THC) on cerebral blood flow (CBF) were studied in human subjects. Regional CBF was measured with 15O-water and Positron Emission Tomography (PET) in 32 volunteers with a history of exposure to marijuana. Scans were performed before and after intravenous (I.V.) infusion of either of two doses of THC or a placebo, given under double blind conditions. RESULTS: THC but not placebo increased CBF especially in the frontal regions bilaterally, insula and cingulate gyrus and sub-cortical regions with somewhat greater effects in the right hemisphere. While most regions showed significant change at 60 minutes for the lower dose group, the higher dose group had significant change at 30 and 60 minutes. There was a highly significant change in the anterior/posterior ratio for the two THC groups reflecting minimal change in occipital flow but significant increases in frontal flow. Self ratings of THC intoxication showed significant effects, and regression analysis indicated it correlated most markedly with the right frontal region. CONCLUSION: Behavioral manifestations of marijuana intoxication may be associated with increased functional activity of the brain especially the frontal cortex, insula and cingulate gyrus.

Acute changes in cranial blood flow after cocaine hydrochloride.

Cerebral blood flow (CBF) was measured with the 133Xenon inhalation technique and forehead skin flow with laser Doppler, before and twice after 0.3 milligram/kilogram of cocaine hydrochloride and a placebo given intravenously to six cocaine abusers, during two visits, separated by a minimum of one week. After cocaine, subjects showed significant increases in intoxication and tension. Systolic blood pressure and pulse rate also increased significantly after the drug but not after the placebo. CBF, with and without correction for end-tidal CO2, showed increases in left and right hemisphere after cocaine. The CBF increase was maximal in frontal, central and parietal regions. CBF changes correlated only with changes in a rated level of intoxication. Forehead skin flow did not change after cocaine or placebo. In habitual cocaine abusers, 0.3 mg/kg of cocaine, given intravenously produced increased CBF and no changes in forehead skin flow.

A retrospective study of the concept of spirituality as understood by recovering individuals.

In 62 individuals recovering from substance abuse, materialism and spiritualism and cognitive patterns were quantified, before (retrospectively) and after recovery with the Mathew Materialism Spiritualism Scale (MMSS) and a Cognitive Patterns Questionnaire (CPQ). MMSS was also administered once to 61 general controls. Recovering individuals showed highly significant prerecovery to postrecovery increases in spirituality on most subscales of MMSS and changes in cognitive patterns. Sixteen controls who met the criteria for alcoholism on the Michigan Alcoholism Screening Test (MAST-positive) were separated from the others. Prerecovery MMSS scores did not differentiate the recovering individuals from MAST-positive controls. However, the prerecovery MMSS scores obtained by recovering individuals were significantly lower than the scores obtained by the MAST-negative controls. On the other hand, after recovery, recovering individuals showed higher MMSS spirituality scores in comparison to MAST-positive controls. The only MMSS item that differentiated recovering individuals after recovery from MAST-negative controls was mysticism with the recovering group obtaining higher scores.

Measurement of materialism and spiritualism in substance abuse research.

OBJECTIVE: A modified version of an instrument called the Mathew Materialism-Spiritualism Scale (MMSS), originally developed in India, was evaluated for possible use in substance abuse research in the U.S. METHOD: The scale was administered to 62 individuals recovering from substance use, 20 clergy people and 61 general controls. RESULTS: Test-retest reliability for the MMSS was verified by administering it to 18 control subjects on two separate occasions, 7 days apart. The Pearson correlation for the MMSS total scores was 0.83 (p < .0001). Internal consistency was examined with Cronbach's alpha in the entire sample of 143 subjects; the result for the total score was .93. Factor analysis showed a factor structure compatible with the subscales proposed by the developer. Women, in general, obtained higher spirituality scores. Members of the recovering group obtained significantly higher scores on "character" and "mysticism" than the general controls. When general controls were divided into MAST positive and MAST negative individuals, the MAST positive group obtained lower scores than the recovering group for "God," "mysticism" and "character." MAST negative individuals had lower scores on "mysticism" than the recovering group. Christians had higher scores on "God" and "religion" subscales than did nonChristians and agnostics. CONCLUSIONS: The results of this study need confirmation using an improved methodology and larger sample sizes. However, they suggest that the scale may be useful for the study of spirituality in the U.S.

Effects of marijuana on performance of a computerized cognitive-neuromotor test battery.

To evaluate the sensitivity of a computerized cognitive-neuromotor test battery in assessing the effects of marijuana (delta-9-tetrahydrocannabinol [THC]), we conducted a study of 10 healthy male volunteers who were experienced marijuana smokers. After extensive training on the performance tasks, each subject was tested on three separate days after smoking a cigarette containing either 1.75% THC, 3.55% THC, or placebo according to a randomized double-blind repeated measures design. Testing was carried out before smoking and 30, 90, and 150 minutes after smoking the cigarette. Of the five tasks employed, the digit-symbol substitution test with memory and the reaction time task were the measures most sensitive to effects of marijuana. We examined the usefulness of the coefficient of variation and effect size as indices of sensitivity to be used across different types of tasks.

Cerebral blood flow and metabolism in anxiety and anxiety disorders.

Anxiety disorders are some of the commonest psychiatric disorders and anxiety commonly co-exists with other psychiatric conditions. Anxiety can also be a normal emotion. Thus, study of the neurobiological effects of anxiety is of considerable significance. In the normal brain, cerebral blood flow (CBF) and metabolism (CMR) serve as indices of brain function. CBF/CMR research is expected to provide new insight into alterations in brain function in anxiety disorders and other psychiatric disorders. Possible associations between stress I anxiety I panic and cerebral ischemia I stroke give additional significance to the effects of anxiety on CBF. With the advent of non-invasive techniques, study of CBF/CMR in anxiety disorders became easier. A large numbers of research reports are available on the effects of stress, anxiety and panic on CBF/CMR in normals and anxiety disorder patients. This article reviews the available human research on this topic.

Asymmetry of rCBF in schizophrenia: relationship to AP-gradient and duration of illness.

This article examines patients with schizophrenia and controls to determine whether asymmetry and anteroposterior (AP) gradient of cerebral blood flow (CBF) are related to duration of illness, and whether they are themselves correlated. CBF was measured with the 133xenon inhalation technique in 108 patients and 108 age-matched and gender-matched controls while the subjects were at rest. Two sets of analyses were performed. The first analyses indicated AP-gradient to be reduced in patients, and hemispheric asymmetry scores to be different from controls only in the temporal area. The second set of analyses were based on two groups of 27 patients, selected to represent extremes on duration of illness (less than 5 and greater than 12 years) and equal numbers of age-matched and gender-matched controls. These analyses revealed patients of both short and long duration of illness to have significantly greater temporal asymmetry, whereas only long-duration patients had significant AP-gradient relative to both controls and short-duration patients. Regression analyses from each data set found AP-gradient to be related to duration of illness, whereas temporal asymmetry was not, temporal asymmetry and AP-gradient were not correlated. These results suggest AP-gradient and temporal asymmetry may reflect independent processes.