Cerebral white matter disruption in Creutzfeldt-Jakob disease

BACKGROUND AND PURPOSE

Human prion diseases are known to cause gray matter degeneration in specific cerebral structures, but evidence for white matter involvement is scarce. We used DTI to test the hypothesis that white matter integrity is disrupted in human CJD during the early stages of the disease.

MATERIALS AND METHODS

Twenty-one patients with the E200K variant of CJD and 19 controls participated in DTI studies conducted on a 1.5T MR imaging scanner. The data were quantitatively analyzed and mapped with a voxelwise TBSS method.

RESULTS

We found significant reductions of FA in patients with CJD in distinct and functionally relevant white matter pathways, including the corticospinal tract, internal capsule, external capsule, fornix, and posterior thalamic radiation. Moreover, these FA deficits increased with disease duration, and were mainly determined by increase of radial diffusivity, suggesting elevated permeability of axonal membranes.

CONCLUSIONS

The findings suggest that some of the symptoms of CJD may be caused by a functional dysconnection syndrome, and that the leukoencephalopathy is progressive and detectable fairly early in the course of the disease.

Characterization of movement disorders in patients with familial Creutzfeldt-Jakob disease carrying the E200K mutation

BACKGROUND

While myoclonus and ataxia are considered common in patients with familial Creutzfeld-Jakob disease (fCJD), other movement disorders are less prevalent.

OBJECTIVES

To systemically evaluate the frequency of extrapyramidal signs and movement disorders in patients with fCJD.

METHODS

A detailed neurological examination, with special emphasis on movement disorders and extrapyramidal signs, was conducted in 43 consecutive symptomatic CJD patients (26 males and 17 females; mean age 58.7 +/- 8.9 yrs, range 43-77 years) carrying the E200K mutation in the PRNPgene.

RESULTS

Limb or gait ataxia was noted in 38 patients (88%) (37 patients, 86%, had ataxia at presentation). Myoclonus was evident in 25/43 patients (58%) (21 patients, 49%, at presentation). In 95% of the patients (41/43) (37/43, 86% at presentation) at least one extrapyramidal sign throughout the disease course was noted, the most prevalent being rigidity (28/43, 65% of the patients; and 22/43, 51% at presentation), followed by the glabellar sign (24/43, 56% of the patients; and 22/43, 51% at presentation), bradykinesia (19/43, 44%; and 15/43, 35% at presentation), dystonia (15/43, 35%; 12/43, 28% at presentation) and tremor (13/43, 30%; 12/43, 28% at presentation).

CONCLUSIONS

In this unique population of fCJD patients, myoclonus was less prevalent than previously reported while other extrapyramidal signs were common and occurred at a relatively early stage of the disease. The high prevalence of movement disorders can be added to other phenomena characteristic of this familial disorder among Libyan lews. Whether this is attributable to the E200K mutation itself or to some other mechanism has still to be elucidated.

The Creutzfeldt-Jakob disease (CJD) neurological status scale: a new tool for evaluation of disease severity and progression

OBJECTIVES

To develop a scale sensitive for the neurological manifestations of Creutzfeldt-Jakob disease (CJD).

METHODS

A 26-item CJD neurological status scale (CJD-NS) was created based on characteristic disease manifestations. Each sign was assigned to one of eight neurological systems to calculate a total scale score (TSS) and a system involvement score (SIS). The scale was administered to 37 CJD patients, 101 healthy first-degree relatives of the patients and 14 elderly patients with Parkinson's disease (PD).

RESULTS

The mean TSS (±SD) was significantly higher in patients with CJD (13.19 ± 5.63) compared with normal controls (0.41 ± 0.78) and PD patients (9.71 ± 3.05). The mean SIS was also significantly different between the CJD (5.19 ± 1.22) and PD (2.78 ± 1.18 P ≤ 0.01) groups reflecting the disseminated nature of neurological involvement in CJD. Using a cutoff of TSS > 4 yielded a sensitivity of 97% for CJD, and specificity of 100% against healthy controls. All individual items showed excellent specificity against healthy subjects, but sensitivity was highly variable. Repeat assessments of CJD patients over 3-9 months revealed a time-dependent increase in both the TSS and the SIS reflecting the scale's ability to track disease progression.

CONCLUSIONS

The CJD-NS scale is sensitive to neurological signs and their progression in CJD patients.

The EEG in E200K familial CJD: relation to MRI patterns

The aim of the study was to examine the relationship between EEG abnormalities and the pattern of MRI changes in familial Creutzfeldt-Jakob Disease (fCJD) patients with E200K mutation. As part of a controlled, prospective study, 13 E200K fCJD patients underwent comprehensive evaluations, with EEG and an extensive MRI protocol that included one of the most prion-disease sensitive sequences, diffusion-weighted imaging (DWI). The relationship between EEG abnormalities and the pattern of DWI hyperintensities was examined. EEG demonstrated the classical CJD finding of PSWC (periodic sharp wave complexes) in five patients (38%) while in eight patients (62%) the EEG showed only slow activity. Six patients showed the typical cortical changes on MRI, and in five of them (83%) concordance between the MRI and the EEG was found. Five patients had isolated basal ganglia involvement per MRI, and in two of them (40%) concordance between the MRI and the EEG laterality was found. In the remaining two patients MRI did not show any changes suggesting CJD and EEG showed focal slow activity. The EEG of our E200K fCJD patients appears similar to that of the largest prion disease patient group, sporadic CJD (sCJD). EEG abnormalities in E200K fCJD appear to correlate mainly with cortical pathology, as revealed by DWI, rather than basal ganglia pathology. The observation that PSWC abnormalities reflect cortical rather than basal ganglia pathology is significant with respect to theories of the origins of EEG abnormalities in prion disease.

Hypertension impairs vascular reactivity in the pediatric brain

BACKGROUND AND PURPOSE

Chronic hypertension impairs cerebrovascular regulation in adults, but its effects on the pediatric population are unknown. The objective of this study was to investigate cerebrovascular abnormalities in hypertensive children and adolescents.

METHODS

Sixty-four children and adolescents aged 7 to 20 years underwent transcranial Doppler examinations of the middle cerebral artery at the time of rebreathing CO2. Time-averaged maximum mean cerebral blood flow velocity and end-tidal CO2 were used to quantify cerebrovascular reactivity during hypercapnia. Patients were clinically categorized as hypertensive, prehypertensive, or white coat hypertensive based on 24-hour ambulatory blood pressure measurements. Their reactivities were compared with 9 normotensive control subjects and evaluated against baseline mean blood pressure z-scores and loads.

RESULTS

Untreated hypertensive children had significantly lower hypercapnic reactivity than normotensive children (2.556 +/- 1.832 cm/s x mm Hg versus 4.256 +/- 1.334 cm/s x mm Hg, P < 0.05). Baseline mean diastolic blood pressure z-scores (r = -0.331, P = 0.037) and diastolic blood pressure loads (r = -0.351, P = 0.026) were inversely related to reactivity.

CONCLUSIONS

Untreated hypertensive children and adolescents have blunted reactivity to hypercapnia, indicating deranged vasodilatory reactivity. The inverse relationship between diastolic blood pressure indices and reactivity suggests that diastolic blood pressure may be a better predictor of cerebral end organ damage than systolic blood pressure.

Pruritus in familial Creutzfeldt-Jakob disease: a common symptom associated with central nervous system pathology

Pruritus, a common feature of animal prion diseases such as scrapie, is rarely reported in humans with Creutzfeldt-Jakob disease (CJD), and its anatomical background is not well defined. The present study was undertaken to carry out a methodical prospective search for the prevalence of pruritus in CJD patients and investigate its anatomical substrate by MRI. The study group included consecutive familial and sporadic CJD patients carrying the E200K PRNP mutation followed up in a longitudinal prospective study between the years 2005 and 2008. Pruritus was prospectively screened for and diffusion-weighted imaging (DWI) was used to correlate brain diffusion abnormalities with pruritus in CJD patients. Pruritus was present in 6/31 (19.35%) patients with familial disease (fCJD) and in none of the patients with sporadic disease (sCJD). Pruritus was a presenting symptom in one patient and evolved during the course of the disease in the other five patients. The pruritus was generalized in three patients, regional in two and localized in one patient. It was transient in one patient and continued throughout the disease in five patients. DWI showed that pruritus was significantly associated with reduced diffusion in the several areas known to be affected by CJD, but most significantly in the midbrain periaqueductal grey matter. Pruritus is relatively common in patients with familial CJD carrying the E200K mutation. Our findings point to a central origin that involves damage to the inhibitory gating mechanism for itch in the periaqueductal grey matter.

Rapidly progressive Creutzfeldt-Jakob disease in patients with Familial Mediterranean Fever

BACKGROUND

The largest cluster of familial Creutzfeldt-Jakob disease (fCJD) exists in Jews of Libyan origin. Familial Mediterranean fever (FMF) is an inflammatory disease also common in this population.

OBJECTIVES

We hypothesized that FMF, as a pro-inflammatory condition, may affect the course of CJD.

METHODS

Three hundred and seventy-two consecutive patients diagnosed clinically and genetically as CJD were included in the study. Two hundred and thirty-six had fCJD, and 136 had sporadic disease (sCJD). Review of the patient's records revealed three patients with FMF-CJD co-morbidity. In addition, 50 DNA samples of patients with CJD were genotyped as homozygote, heterozygote, and non-carriers of the FMF mutation. The demographic and clinical variables of the groups were compared.

RESULTS

The three patients with FMF had an earlier age of onset and significantly shorter disease duration than the patients without FMF. Heterozygote carriers did not differ in disease onset and duration from patients without FMF.

CONCLUSIONS

The shorter disease duration of CJD patients with FMF may indicate the importance of pro-inflammatory factors in the disease.

Putaminal volume and diffusion in early familial Creutzfeldt-Jakob disease

BACKGROUND

The putamen is centrally implicated in the pathophysiology of Creutzfeldt-Jakob Disease (CJD). To our knowledge, its volume has never been measured in this disease. We investigated whether gross putaminal atrophy can be detected by MRI in early stages, when the diffusion is already reduced.

METHODS

Twelve familial CJD patients with the E200K mutation and 22 healthy controls underwent structural and diffusion MRI scans. The putamen was identified in anatomical scans by two methods: manual tracing by a blinded investigator, and automatic parcellation by a computerized segmentation procedure (FSL FIRST). For each method, volume and mean Apparent Diffusion Coefficient (ADC) were calculated.

RESULTS

ADC was significantly lower in CJD patients (697+/-64 microm(2)/s vs. 750+/-31 microm(2)/s, p<0.005), as expected, but the volume was not reduced. The computerized FIRST delineation yielded comparable ADC values to the manual method, but computerized volumes were smaller than manual tracing values.

CONCLUSIONS

We conclude that significant diffusion reduction in the putamen can be detected by delineating the structure manually or with a computerized algorithm. Our findings confirm and extend previous voxel-based and observational studies. Putaminal volume was not reduced in our early-stage patients, thus confirming that diffusion abnormalities precede detectible atrophy in this structure.

Enhanced detection of diffusion reductions in Creutzfeldt-Jakob disease at a higher B factor

BACKGROUND AND PURPOSE

Diffusion-weighted imaging (DWI) is sensitive to the cerebral manifestations of human prion diseases. The magnitude of diffusion weighting, termed "b factor," has only been evaluated at the standard b = 1000 s/mm(2). This is the first rigorous evaluation of b = 2000 s/mm(2) in Creutzfeldt-Jakob Disease (CJD).

MATERIALS AND METHODS

We compared DWI characteristics of 13 patients with CJD and 15 healthy controls at b = 1000 s/mm(2) and b = 2000 s/mm(2). Apparent diffusion coefficients (ADC) were computed and analyzed for the whole brain by voxel-wise analysis (by SPM5) as well as in anatomically defined volumes of interest (by FSL FIRST).

RESULTS

Measured ADC was significantly lower (by approximately 5%-15%) at b = 2000 s/mm(2) than at b = 1000 s/mm(2) and significantly lower in patients than in controls. The differences between patients and controls were greater and more extensive at b = 2000 s/mm(2) than at b = 1000 s/mm(2) in the expected regions (thalamus, putamen, and caudate nucleus).

CONCLUSIONS

Because higher b factors change the absolute value of observed ADC, as well as lesion detection, care should be taken when combining studies using different b factors. While the clinical application of high b factors is currently limited by a low signal intensity-to-noise ratio, it may offer more information in questionable cases, and our results confirm and extend the central role of diffusion imaging in human prion diseases.

Memory activation in healthy nonagenarians

Little is known about brain function in the oldest old, although this is the fastest growing segment of the population in developed countries and is of paramount importance in public health considerations. In this study, we investigated the cerebral response to a memory task in healthy subjects over age 90 compared with healthy younger elderly. We studied 29 healthy elderly subjects, 12 over age 90 and 17 between age 70 and 80. All subjects were cognitively intact, as verified by a neuropsychological battery, and performed a nonverbal memory task while undergoing a functional MRI (fMRI). Activation results were analyzed by a random-effects ANCOVA using SPM5. The task resulted in activation of similar areas of the posterior temporal, parietal, and posterior frontal cortexes, but the activation was more robust in the younger subjects, especially in the right hippocampus, and parietal and temporal cortices. This finding remained after controlling for education, cognition, task performance or cerebral atrophy. The phenomenon of relatively maintained performance, despite significant brain atrophy and lower activation is consistent with the cognitive reserve theory and may be specific to subjects with extremely successful aging. Further investigation of brain activation patterns in the oldest old is warranted.

Hemodynamic etiology of elevated flow velocity and stroke in sickle-cell disease

Elevation of blood flow velocity in the large cerebral vessels is known to be of substantial pathophysiologic and prognostic significance in sickle-cell disease (SCD). Its precise cause is not established, but the two obvious proximal mechanisms are obstructive vascular stenosis and hemodynamic dilatation. Here we revisit this distinction by analyzing cerebrovascular reserve capacity. Forty-two patients with SCD underwent measurements of global cerebral blood flow in grey matter by the 133Xe inhalation method during normocapnia and hypercapnia to quantify cerebrovascular reactivity. Cerebral blood flow was significantly higher in SCD patients (120+/-31 ml/100 g/min) than in controls (76+/-20 ml/100 g/min). Reactivity was significantly lower in SCD patients (1.06+/-1.92 versus 2.16+/-1.15%/mm Hg). Stepwise multiple regressions within the SCD sample determined that normocapnic cerebral blood flow was largely predicted by hematocrit (r=-0.59; P<0.0001), whereas hypercapnic reactivity was only predicted by normocapnic flow across all subjects (r=-0.52; P<0.0001). None of the controls, but 24% of the SCD patients showed 'steal' (negative reactivity, chi2=6.05; P<0.02). This impairment of vasodilatory capacity, occurring at perfusion levels above 150 ml/100 g/min, may reflect intrinsic limitations of the human cerebrovascular system and can explain both the elevated blood flow velocities and the high risk of stroke observed in such patients.

Thalamo-striatal diffusion reductions precede disease onset in prion mutation carriers

Human prion diseases present substantial scientific and public health challenges. They are unique in being sporadic, infectious and inherited, and their pathogen is distinct from all other pathogens in lacking nucleic acids. Despite progress in understanding the molecular structure of prions, their initial cerebral pathophysiology and the loci of cerebral injury are poorly understood. As part of a large prospective study, we analysed early diffusion MRI scans of 14 patients with the E200K genetic form of Creutzfeldt-Jakob Disease, 20 healthy carriers of this mutation that causes the disease and 20 controls without the mutation from the same families. Cerebral diffusion was quantified by the Apparent Diffusion Coefficient, and analysed by voxel-wise statistical parametric mapping technique. Compared to the mutation-negative controls, diffusion was significantly reduced in a thalamic-striatal network, comprising the putamen and mediodorsal, ventrolateral and pulvinar thalamic nuclei, in both the patients and the healthy mutation carriers. With disease onset, these diffusion reductions intensified, but did not spread to other areas. The caudate nucleus was reduced only after symptomatic onset. These findings indicate that cerebral diffusion reductions can be detected early in the course of Creutzfeldt-Jakob Disease, and years before symptomatic onset in mutation carriers, in a distinct subcortical network. We suggest that this network is centrally involved in the pathogenesis of Creutzfeldt-Jakob Disease, and its anatomical connections are sufficient to account for the common symptoms of this disease. Further, we suggest that the abnormalities in healthy mutation-carrying subjects may reflect the accumulation of abnormal prion protein and/or associated vacuolation at this time, temporally close to disease onset.

Cross-validation of brain segmentation by SPM5 and SIENAX

Volumes of cerebral grey (GM) or white matter (WM) are often used as clinical observations or statistical covariates. Several automated segmentation tools can be used for this purpose, but they have not been validated against each other. We used the most common ones, SPM5 and SIENAX 2.4, to derive volumes of grey and white matter in 56 healthy subjects (mean age 49+/-13, range 22-80) and compared the two methods. Both methods yielded significant correlations with age in the expected directions, and estimates of parenchymal volumes were highly correlated. However, without use of prior probability maps, or priors, in SIENAX, GM was significantly underestimated in comparison to SPM (0.52+/-.06 vs 0.66+/-.07 L) and WM was significantly overestimated (0.48+/-.07 vs 0.46+/-.07 L). This error was associated with misclassification of GM as cerebrospinal fluid, especially in deep grey matter. Invoking prior probabilities in SIENAX resulted in excellent agreement with SPM: GM and WM volumes were found to be 0.64+/-0.07 L and 0.47+/-0.07 L, respectively. We conclude that SIENAX requires priors for accurate volumetric estimates, and then provides close agreement with SPM5.

MR imaging of familial Creutzfeldt-Jakob disease: a blinded and controlled study

BACKGROUND AND PURPOSE

The E200K mutation of the PRNP (prion protein) gene is the most common cause of familial Creutzfeldt-Jakob disease (fCJD), which has imaging and clinical features that are similar to the sporadic form. The purpose of this study was to conduct a controlled and blinded evaluation of the sensitivity and specificity of MR imaging in this unique population.

MATERIALS AND METHODS

We compared the MR imaging characteristics of 15 early stage familial CJD patients (age, 60 +/- 7 years) with a group of 22 healthy subjects from the same families (age, 61 +/- 8 years). MR imaging included diffusion-weighted imaging (DWI), T2-weighted fast spin-echo imaging, and a fluid-attenuated inversion recovery (FLAIR) sequence. The scans were rated for abnormalities by an experienced neuroradiologist blind to diagnosis, group assignment, age, and sex.

RESULTS

Thirteen of 15 fCJD subjects had abnormal MR imaging. FLAIR signal intensity abnormality in the caudate or putamen nuclei demonstrated a sensitivity of 87% and specificity of 91%. DWI abnormality in the caudate nucleus showed a sensitivity of 73% and a specificity of 100%. Abnormalities in the thalamus (6 patients), cingulate gyrus (6 patients), frontal lobes (4 patients), and occipital lobes (3 patients) were best detected with DWI. No signal intensity abnormalities were demonstrated in the cerebellum. T2-weighted and T1-weighted sequences were uninformative.

CONCLUSIONS

FLAIR and DWI abnormalities in the caudate nucleus and putamen offer the best sensitivity and specificity for diagnosing fCJD. Our findings support recent recommendations that MR imaging should be added to the diagnostic evaluation of CJD.

Cerebrovascular effects of hemodialysis in chronic kidney disease

Patients with end-stage renal disease (ESRD) undergoing hemodialysis are known to suffer cognitive deficits and stroke of unknown etiology. It has been suspected that the treatment itself may contribute to the syndrome by unknown mechanisms, which we investigated in this study. End-stage renal disease patients on hemodialysis (n=19) or peritoneal dialysis (PD, n=5) were compared with 14 healthy controls. Subjects participated in magnetic resonance imaging (MRI) measurements of cerebral atrophy, cerebral blood flow (CBF) arterial spin labeled-MRI (ASL-MRI), quantitative Doppler blood flow through the internal carotid artery, and cerebral oxymetry. The Doppler and oxymetry procedures were also performed at the beginning and end of a single hemodialysis session. End-stage renal disease patients on hemodialysis showed significant cerebral atrophy, associated with longer hemodialysis duration and cognitive deficits, including focal bilateral lesions in the caudate nucleus and midbrain. Cerebral oxygenation was extremely low before dialysis (rSO(2) 41+/-13, compared with 70+/-2 in controls, P<0.02) and improved only slightly after dialysis. Carotid blood flow was also very low at the start of dialysis (115+/-28 mL/sec, versus 193+/-56 in controls, P<0.005) but normalized at the end of the session (181 mL/sec). The PD patients showed intermediate values, between the hemodialysis and controls. Notably, duration of hemodialysis treatment predicted global gray-matter volume (r=-0.74), change of blood flow during dialysis (r=-0.65), and baseline rSO(2) (r=-0.65). The findings suggest that ESRD patients on hemodialysis suffer low CBF during the interdialytic cycle. Coupled with low cerebral oxygenation levels and atherosclerosis, this may contribute significantly to the etiology of the observed cerebral atrophy, cognitive deficits, and high stroke prevalence.

The imaging appearance of Creutzfeldt-Jakob disease caused by the E200K mutation

The E200K mutation on chromosome 20 can cause familial Creutzfeldt-Jakob disease (CJD). Patients with this mutation are clinically similar to those with sporadic CJD, but their imaging features are not well documented. We report here the quantitative and qualitative evaluation of the magnetic resonance (MR) imaging characteristics of this unique group of patients using three-dimensional spoiled gradient recalled (SPGR) echo images, diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) measurements, MR spectroscopy and a fluid-attenuated inversion recovery (FLAIR) sequence. The SPGR and ADC data were analyzed with SPM99. ANCOVA and regression models were used for a region-of-interest (ROI) analysis of ADC and metabolic ratios. CJD patients had a decreased fraction of gray matter and an increased fraction of cerebrospinal fluid (P=.001) in the cortex and cerebellum and increased ADC values in the cortex (P<.001). Focal decreases of ADC were found in the putamen via ROI analysis (548+/-83 vs. 709+/-9 microm(2)/s, P=.02). N-acetyl aspartate (NAA) was generally reduced, with the NAA/Cho ratio lowest in the cingulate gyrus. Qualitative assessment revealed hyperintensities on FLAIR, DWI or both in the putamen (three out of four patients), caudate (three out of four patients) and thalamus. These results provide a framework for future study of patients with genetically defined familial CJD.

Dissociation of neuropathology from severity of dementia in late-onset Alzheimer disease

BACKGROUND

Little is known about Alzheimer disease at advanced ages, although its incidence continues to increase at least through the ninth decade of life.

OBJECTIVE

To examine the effects of age on the relationship between clinical dementia severity and neuropathologic hallmarks in a large sample spanning the full age range.

METHODS

The authors assessed 81 subjects during life for dementia severity, and examined their brains. They analyzed plaque and tangle burden, as well as the activities of the cholinergic marker enzymes acetylcholinesterase (AChE) and choline acetyltransferase (ChAT), in relation to age at death and the clinical severity of dementia.

RESULTS

Dementia severity was strongly related to plaque and tangle burden in relatively young patients (aged < 75 years), but this correlation diminished with age and disappeared in the ninth decade of life. Among the oldest patients studied, there was no difference in plaque and tangle load between the mild and severe dementia cases. This interaction (p < 0.0001 for plaque density) was not observed for the cholinergic markers ChAT and AChE.

CONCLUSION

The nature or expression of Alzheimer disease may be different in severely demented older patients, who have equal cholinergic deficits but significantly lower plaque and tangle burden. If confirmed in a prospective study, these findings have diagnostic and therapeutic implications.

Tolerance of MRI procedures by the oldest old

OBJECTIVES

The study aimed to evaluate the feasibility and discomfort of magnetic resonance imaging (MRI) procedures in the oldest-old subjects (age > 90 years) using a survey design in a university-affiliated neuroimaging research center.

PARTICIPANTS

Forty-one community-dwelling, elderly subjects were considered for participation. Twenty-nine of them underwent voluntary, extensive MRI scanning (up to 1 h) as part of a project on brain function in the oldest old. Thirteen oldest old (OO, range 90-93 years, mean 92 years) were compared to 16 young old (YO, range 72-80 years, mean 76 years).

MEASUREMENTS

Likert-style questionnaire on satisfaction following extensive MRI scanning session (up to 1 h) was administered. Data were analyzed by an analysis of variance (gender by age group).

RESULTS

All subjects reported positive experiences with no significant difficulties or concerns. There were minor differences in some rated items, with the OO and males slightly less comfortable than YO and females, respectively. Overall, the OO tolerated the procedures as well as the YO.

CONCLUSION

Very long MRI sessions are feasible, even in the oldest-old subjects, and are not associated with any significant discomfort. Prior screening and thorough education of the subjects probably help to minimize anxiety and dropout.

Metabolic interaction between ApoE genotype and onset age in Alzheimer's disease: implications for brain reserve

BACKGROUND

Clinically apparent Alzheimer's disease (AD) is thought to result when brain tissue damage exceeds a critical threshold of "brain reserve", a process possibly accelerated by the apolipoprotein E (ApoE) E4 allele. The interaction between onset age and ApoE genotype was investigated to assess whether early disease onset (<65 years) in patients carrying the E4 allele is associated with greater cerebral metabolic (regional cerebral metabolic rate of glucose utilisation, rCMRgl) reduction.

METHODS

AD patients, divided into early (EOAD; 27 patients) and late onset (LOAD; 65 patients) groups, both groups balanced as to the number of E4 carriers (E4+) and non-carriers (E4-), and matched controls (NC; 35 cases) underwent (18)F-FDG PET ([(18)F]fluorodeoxyglucose positron emission tomography) scanning. SPM'99 software was used to compare AD patients to NC and to perform a two way ANOVA with onset age and ApoE genotype as grouping factors. Results were considered significant at p<0.001, uncorrected.

RESULTS

AD patients demonstrated rCMRgl reductions compared to NC, with rCMRgl lower in association cortex and relatively higher in limbic areas in EOAD compared to LOAD subjects. rCMRgl was lower in the anterior cingulate and frontal cortex for E4+ compared to E4- subjects. A significant onset age by ApoE interaction was detected in the hippocampi and basal frontal cortex, with EOAD E4+ subjects having the greatest rCMRgl reduction.

CONCLUSIONS

The interactive effects of early onset age, possibly reflecting lower brain reserve, and ApoE E4 allele, possibly leading to greater tissue damage, lead to reduced tolerance to the pathophysiological effects of AD in key brain regions.

Functional MRI changes before and after onset of reported emotions

The social nature of emotion is evident in the importance of facial and vocal displays in emotion-related behavior. This is the first brain-imaging study to use simulated face-to-face social interactions to evoke emotional responses and to compare valence-related activations before and after subjective onset of emotional response. Videotapes were prepared with actresses who described happy or unhappy experiences. Functional magnetic resonance imaging (fMRI) at 1.5 T was used to acquire BOLD images in 21 healthy young adults before, after, and during viewing of the happy and sad tapes. Subjects pushed buttons to indicate the onset of subjective emotional responses. Group data were analyzed by a bootstrap randomization method after anatomical normalization. Significant activation was detected in frontal and sensory regions prior to the reported onset of emotional response, and this activity showed a marked decrease after the report of conscious emotional experience. Significant differences between happy and sad conditions were evident in multiple brain regions both before and after the reported onset of emotional response, including the middle and superior temporal gyri, the middle frontal gyrus, the caudate, and the hippocampus. Socially relevant emotional stimulation is feasible and evokes robust responses. The neural correlates of the evoked emotion are multiple, widely distributed, and inclusive of areas important in many cognitive tasks. Positive and negative emotional responses include activation of common and distinctive brain regions.

Regional cerebral blood flow and cognitive deficits in chronic lyme disease

This study examined brain functioning in patients with Lyme encephalopathy. Eleven patients underwent neuropsychological tests and Xenon(133)-regional cerebral blood flow (rCBF) studies, using an external detector system. Each rCBF scan was age- and sex-matched to two archival, normal controls. While few differences were noted on gray-matter flow indices (ISI, fg), Lyme patients demonstrated significant flow reductions in white matter index (k(2)) (p=.004), particularly in the posterior temporal and parietal lobes bilaterally (p=.003). Flow reductions in white matter areas were significantly associated with deficits in memory (r=.66, p=.027) and visuospatial organization (r=.62, p=.041). Results suggest that Lyme encephalopathy may be a disease primarily affecting the cerebral white matter.

Increased cerebral blood flow after brain arteriovenous malformation resection is substantially independent of changes in cardiac output

Brain arteriovenous malformation (BAVM) resection can result in an acute increase in cerebral blood flow (CBF) of unclear etiology. This observational study investigated the relationship between changes in CBF and cardiac output (CO) in patients undergoing microsurgical resection of BAVMs. In 20 patients undergoing a BAVM resection during an isoflurane-based anesthesia, we measured CBF and systemic cardiovascular parameters immediately before and after BAVM resection. CBF was measured on the hemisphere ipsilateral to the lesions and on the contralateral side, using intravenous cold 133Xe washout. Cardiac output was measured using thermodilution technique via a pulmonary artery catheter. There was an increase in global CBF after resection (25 +/- 8 versus 31 +/- 13 mL/100 g/min, preresection versus postresection, mean +/- SD, P =.002), ipsilateral CBF (25 +/- 8 versus 31 +/- 13 mL/100 g/min, P =.002), and contralateral CBF (24 +/- 7 versus 30 +/- 13 mL/100 g/min, P =.003). There was no change in CO, mean systemic arterial pressure, central venous pressure, or pulmonary artery diastolic pressure. The change in CBFGLOBAL was not correlated with changes in CO (r =.154, P =.517). BAVM resection resulted in global increases in CBF that was not substantially related to changes in CO or other systemic parameters.

Sickle cell disease: the neurological complications

The genetic cause of sickle cell disease has been known for decades, yet the reasons for its clinical variability are not fully understood. The neurological complications result from one point mutation that causes vasculopathy of both large and small vessels. Anemia and the resultant cerebral hyperemia produce conditions of hemodynamic insufficiency. Sickled cells adhere to the endothelium, contributing to a cascade of activated inflammatory cells and clotting factors, which result in a nidus for thrombus formation. Because the cerebrovascular reserve becomes exhausted, the capacity for compensatory cerebral mechanisms is severely limited. There is evidence of small-vessel sludging, and a relative deficiency of nitric oxide in these vessels further reduces compensatory vasodilatation. Both clinical strokes and silent infarcts occur, affecting motor and cognitive function. New data suggest that, in addition to sickle cell disease, other factors, both environmental (eg, hypoxia and inflammation) and genetic (eg, mutations resulting in thrombogenesis), may contribute to a patient's stroke risk. The stroke risk is polygenic, and sickle cell disease can be considered a model for all cerebrovascular disease. This complex disease underscores the potential intellectual and practical distance between the determination of molecular genetics and effective clinical application and therapeutics.

Regional cerebral blood flow in mood disorders, V.: Effects of antidepressant medication in late-life depression

Twenty elderly outpatients with major depression were treated with either nortriptyline or sertraline. Resting regional cerebral blood flow (rCBF) was assessed by the planar (133)Xenon inhalation technique after a medication washout and following 6- 9 weeks of antidepressant treatment. At baseline, the depressed sample had reduced rCBF in frontal cortical regions when compared with 20 matched normal-control subjects. After treatment, Responders and Nonresponders differed in the expression of a specific topographic alteration, with Responders manifesting reduced perfusion in frontal regions. These findings are consistent with this group's previous report of reduced rCBF after response to electroconvulsive therapy (ECT) and suggest a common mechanism of action.

Functional magnetic resonance imaging of cocaine craving

OBJECTIVE

Identification of brain activity associated with craving is important for understanding the neurobiology of addiction.

METHOD

Brain activity was measured in cocaine addicts and healthy subjects by functional magnetic resonance imaging (fMRI) while the subjects watched videotapes designed to elicit happy feelings, sad feelings, or the desire to use cocaine. The subjects indicated the onset of drug craving or emotional response, allowing comparison of groups before and after such feelings.

RESULTS

Robust activation of the anterior cingulate was evident in patients watching cocaine-cue tapes but not in patients watching happy or sad tapes or in healthy subjects under any condition. Anterior cingulate activation preceded the reported onset of craving and was evident in patients who did not report craving. In contrast, patients showed less activation than healthy subjects during the cocaine-cue tapes in areas of the frontal lobes. After the reported onset of craving, cocaine-dependent subjects showed greater activity than healthy subjects in regions that are more active in healthy subjects when they watch sad tapes than when they watch happy tapes, suggesting a physiologic link between cocaine-cue responses and normal dysphoric states. Dynamic aspects of regional brain activations, but not the location of activations, were abnormal in cocaine-dependent subjects watching sad tapes, suggesting more general affective dysregulation. Patients showed low activation of sensory areas during initial viewing of all videotapes, suggesting generalized alteration in neuroresponsiveness.

CONCLUSIONS

Cocaine cues lead to abnormally high cingulate and low frontal lobe activation in cocaine addicts. Addicts also show more general abnormalities in affect-related brain activation.

Correlation of basal ganglia magnetic resonance spectroscopy with Apgar score in perinatal asphyxia

BACKGROUND

Brain metabolite levels are measured by proton magnetic resonance spectroscopy (1H MRS) and include N-acetylaspartate (NAA), creatine (Cr), choline (Cho), and lactate and the ratios NAA to Cho and Cr (NAA-ChoCr), NAA-Cr, NAA-Cho, and Cho-Cr. Brain metabolite levels may correlate with the degree of neonatal asphyxia.

OBJECTIVE

To determine which brain metabolite ratios have the strongest correlation with the Apgar scores in infants with possible asphyxia; whether the correlation is stronger with basal ganglia (BG) or anterior border-zone metabolites; and whether a combined approach using routine MR imaging (MRI), diffusion-weighted MRI, and MRS can be used to evaluate the severity of neonatal asphyxia.

METHODS

Twenty infants with 1-minute Apgar scores of 6 or less were studied at 2 to 28 days of age. The MRS variables were compared with routine and diffusion-weighted brain MRI. Clinical variables and MRS findings were subjected to factor analysis and stepwise multiple regressions to determine interrelationships.

RESULTS

The BG region NAA-Cho and NAA-ChoCr ratios correlated with the 1-minute (P<.001) and 5-minute (P = .01 for NAA-Cho; P = .006 for NAA-ChoCr). There was no correlation between metabolite levels and the 10-minute Apgar scores. The stongest predictions exist between the 1-minute Apgar scores and the NAA-Cho and NAA-ChoCr ratios. In the anterior border zone, the only correlation was between the 1-minute Apgar score and the NAA-Cho ratio, but there was a strong age effect in these data. Lactate was found in the BG of 3 infants, all of whom had 5-minute Apgar scores of 6 or less. Three patients had focal lesions on MRI; 2 of these had elevated lactate levels in the abnormal region; and the third, who had an intrauterine stroke, had no lactate in the region.

CONCLUSIONS

Correlations between NAA-Cho and NAA-ChoCr ratios and the 1- and 5-minute Apgar scores are stronger in the BG region than in the frontal border zone. The presence or absence of lactate may indicate the severity of the brain insult, and the combination of MRS, MRI, and diffusion-weighted MRI may assist in localizing and predicting a long-term brain injury.

Cerebral blood flow patterns underlying the differential impairment in category vs letter fluency in Alzheimer's disease

Verbal fluency tasks are used to assess language functioning in Alzheimer's disease (AD), and performance typically declines as the disease progresses. However, several studies have shown that Category Fluency performance (produce words from a category) declines faster than Letter Fluency performance (produce words beginning with a certain letter), which is not the case for other dementias. The purpose of this study was to determine if each of these two types of fluency tasks was associated with different patterns of cerebral blood flow abnormality in AD. A resting, Xenon-inhalation regional cerebral blood flow measurement (133Xe rCBF) and neuropsychological evaluation was administered to 25 patients with probable AD and 24 healthy elderly controls. Stepwise regression using rCBF measures as predictor variables was used to predict Category and Letter Fluency performance, in both a combined group of patients and controls, and in the patient group alone. Correlations were also computed between rCBF variables and the difference between normatively corrected scores on each task for each subject, which characterized the extent of the discrepancy between them. In full sample regressions, both Category and Letter Fluency were predicted by education and the decline in left inferior parietal flow, a focal AD-related deficit. Additional variance in Category fluency, however, was predicted by global mean flow, while additional variance in Letter Fluency was predicted by frontal flow. Within the patient sample, in turn, the primary predictor of Category Fluency was mean flow; the primary predictor of Letter Fluency was left-sided frontal flow. Analysis of the fluency difference score revealed that relatively greater impairment of Category Fluency was associated with more typical, AD-related deficits in posterior temporal and parietal perfusion. When the two were equivalently impaired, typical AD-related deficits were accompanied by marked deficits in frontal perfusion. These findings are consistent with the underlying neuropsychology of these tasks, and suggest that Category Fluency's stronger association to the most typical CBF deficits of AD account for its greater sensitivity to this disease. Letter Fluency deficits, on the other hand, carry significant information about the degree to which perfusion deficits have spread to frontal cortex.

Validation of a Hebrew selective reminding test

We developed a Hebrew version for the Buschke Selective Reminding Memory Test, with three parallel forms. This Hebrew version was administered in counterbalanced order to 24 normal subjects aged 14-77 years. We studied the reliability between parallel forms, and the validity and sensitivity memory reduction in normal aging. Data were compared to American norms. The three Hebrew forms were found to be of equal difficulty, with correlation coefficients of .6 to .7 (p's < .01). Age affected the great majority of memory performances, i.e., lower performance with increasing age. Test performance was equivalent to American norms within 6%. We conclude that this Hebrew version is reliable and valid, and can be used on Hebrew-speaking populations to assess memory functions.

Senile degeneration and cognitive impairment in chronic schizophrenia

OBJECTIVE

This study was an investigation of the role of Alzheimer-type senile degenerative abnormalities in the cognitive impairment of chronic schizophrenia.

METHOD

The study group comprised 145 deceased elderly institutionalized psychiatric patients: 66 with schizophrenia, 26 with mood disorders, 36 with dementia, and 17 with other psychiatric diagnoses. The comparison group included 16 deceased elderly individuals without neurologic or psychiatric disease. Psychiatric diagnoses and cognitive status were established by standardized review of medical records. Neuritic senile plaques and neurofibrillary tangles were identified immunohistochemically and counted, by investigators blind to clinical information, in standardized regions of each brain.

RESULTS

Of the subjects with schizophrenia, 68% had definite cognitive impairment, but only 8% satisfied neuropathological criteria for Alzheimer's disease. Among the schizophrenia subjects without Alzheimer's disease, definite cognitive impairment was associated with higher levels of plaques and tangles. The schizophrenia subjects without definite cognitive impairment had fewer plaques and tangles than the unimpaired nonpsychiatric subjects.

CONCLUSIONS

Most cases of cognitive impairment in schizophrenia could not be attributed to Alzheimer's disease. An association of mild Alzheimer-type pathology with definite cognitive impairment was unique to schizophrenia. Enhanced sensitivity to the effects of aging on the brain may be a manifestation of diminished cognitive reserve in schizophrenia.

Diagnostic yield of brain CT in a limited-access environment

It is not clear why brain CT continues to be used in psychiatric patients in spite of reports of a low yield of useful information. Hypoihetically, in circumstances (such as in Israel) where access to CT is more limited, clinicians will use brain CT more judiciously, resulting in a higher yield. To test this hypothesis, we retrieved and reviewed brain CT results and discharge summaries for 23 patients with abnormal brain scans, from 91 scans performed at two psychiatric inpatient facilities, in order to determine if the brain CT had a significant effect on the diagnosis or treatment of the patient. We found no indication that the abnormal CT findings had a significant effect on the diagnosis or treatment of any of the patients.

Archival, formalin-fixed tissue: its use in the study of Alzheimer's type changes

Preparing for a retrospective study of senile degeneration in schizophrenia, we had occasion to explore the suitability of an old collection formalin-fixed brains and paraffin blocks for study by modern staining methods. Tissue that had been in formalin for 50 years was embedded in paraffin. Sections were then stained with thioflavine S and with immunoperoxidase stains using Alz 50 and antibodies to paired helical filaments, ubiquitin, and beta-amyloid. In all 4 cases that had originally (50 years earlier) received neuropathologic diagnoses of Alzheimer's disease, large numbers of neocortical senile plaques and neurofibrillary tangles were clearly demonstrated by thioflavine S stain and by immunohistochemistry for paired helical filaments, ubiquitin, and beta-amyloid. In each of 4 other cases, in which the original neuropathologic examination had not revealed Alzheimer's disease, no plaques or tangles were observed. Immunoreactivity with Alz 50 was completely absent after 50 years in formalin. Examination of additional cases of Alzheimer's disease revealed that Alz 50 immunoreactivity was well preserved after 10 years in formalin and completely absent after 30 years in formalin. Alzheimer's disease tissue stored in paraffin for 30 years was clearly stained by all modalities. We conclude that immunohistochemical identification of senile plaques and neurofibrillary tangles is practical even after decades of storage in formalin or paraffin. The applicability of techniques that did not exist when these specimens were collected indicates that the systematic, permanent retention of formalin-fixed material may yield unanticipated future benefits.

Physostigmine reversal of scopolamine-induced hypofrontality

The muscarinic receptor antagonist scopolamine produces a transient memory deficit in healthy humans. This deficit has been offered as a model of the cholinergic deficit of Alzheimer's disease (AD). However, we have previously shown that scopolamine produces a deficit of cortical perfusion maximal in the frontal lobe, dissimilar to the parietal cortex deficit characteristic of AD. The current experiment was aimed at replicating and extending this observation by critically testing the central cholinergic origin of both cognitive and perfusion deficits. Nine healthy subjects participated in regional cerebral blood flow (rCBF) measurements at baseline, after scopolamine (7.2 micrograms/kg i.v.), and after both physostigmine (22 micrograms/kg i.v.) and neostigmine (7 or 11 micrograms/kg i.v.). rCBF was quantified by the xenon 133 inhalation method. As expected, scopolamine reduced cortical perfusion, mainly in the frontal cortex, and produced a memory deficit. Physostigmine, but not neostigmine, reversed all three variables partially or completely. These results support the hypothesis that all three consequences of scopolamine, namely, reduction of mean flow, frontal deficit, and memory impairment, are cholinergically mediated. Furthermore, because neostigmine poorly crosses the blood-brain barrier, these findings confirm that the effect is centrally mediated and cannot be explained by peripheral effects. However, they also confirm the frontal cortex locus of action for both scopolamine and its reversal by physostigmine and therefore suggest a major dissimilarity to the characteristic rCBF appearance of AD. This study extends our previous preliminary findings with tacrine and strengthens the suggestion that only nicotinic receptors are associated with the characteristic parietal deficit of AD.

Inferior parietal perfusion, lateralization, and neuropsychological dysfunction in Alzheimer's disease

The severity of inferior parietal perfusion deficits in Alzheimer's disease (AD) is strongly associated with global intellectual decline. The relationship to specific losses of neuropsychological functioning, however, is less clear, as is the relative importance of the side (left vs. right) of hemispheric deficit. In this study, 53 patients with probable AD and 35 elderly controls received both a resting 133Xe rCBF measurement and neuropsychological examination. AD patients demonstrated the expected bilateral deficits in inferior parietal perfusion, as well as impairment on measures of mental status, intelligence verbal and visual memory, attention, language, and construction abilities. The severity of this bilateral parietal deficit, in turn, was associated with virtually all of these AD-related neuropsychological impairments, most strongly with declining Performance IQ. Left-sided deficits correlated better with overall declines in IQ, as well as with declining attention and language fluency. Right-sided deficits, on the other hand, correlated best with declines in mental status and--paradoxically--verbal memory and contributed independently to declines in Full Scale and Performance IQ. In terms of the number and strength of their association to neuropsychological measures, left-sided deficits appear much more predicative of cognitive decline in AD. Right-sided deficits, however, may be most important in predicting aspects of performance skill that are only indirectly assessed in standard paper-and-pencil format. Overall, it appears that both sides make significant, but independent contributions to general functional decline in AD, but that left-sided deficits are more closely associated with cognitive decline in measured by most standard neuropsychological measures.

The economic burden of Alzheimer's disease in Israel

Owing to expected increases in the number of persons at risk for developing Alzheimer's disease and the expected decrease in the number of potential caregivers, the economic burden on society and families is expected to rise. Given changes in demographics and labor force participation, it is likely that the burden will be transferred from informal to formal paid services. Understanding the burden and cost of caring for this large population of patients is essential in order to make rational decisions with regard to allocating resources and providing quality care.

Acute effects of haloperidol on cerebral cortex blood flow in normal and schizophrenic subjects

To evaluate the effects of neuroleptic medications on cerebral blood flow (CBF), cortical perfusion was quantified by the 133xenon technique in 8 unmedicated schizophrenics and 9 healthy controls before, and 1 and 3 hours after, administration of haloperidol (5 mg per os). At 3 hours, the normal subjects, but not schizophrenic patients, showed a significant increase in global mean perfusion (17 +/- 13%). Changes in CBF were not associated with plasma haloperidol levels or the presence of extrapyramidal side effects, and remained significant after controlling for pCO2. The lack of change in CBF in schizophrenic patients following acute haloperidol administration may be due to prior neuroleptic exposure, absence of anxiety, or other nonspecific factors, or may reflect a more fundamental feature of underlying pathophysiology in schizophrenia.

Cortical blood flow and negative symptoms in schizophrenia

An association between negative symptoms and frontal cortex abnormalities has been suggested in schizophrenic patients. We tested whether this association can be found when patients' task performance is good and while controlling for possible cortical atrophy. We investigated regional cerebral blood flow with the xenon-133 inhalation method in 9 unmedicated schizophrenic patients at rest and during performance of the Continuous Performance Test. Negative symptoms were quantified with the Scale for Assessment of Negative Symptoms. All patients could attend to the test and performed it successfully with mean accuracy of 91 +/- 8%. Changes of the left hemisphere hyperfrontality ratio were significantly correlated with severity of negative symptoms, especially for the subscales of attention (r = -0.83) and anhedonia (r = -0.70). These results lend further support to the putative association between negative symptoms and physiological abnormalities of the frontal cortex in schizophrenic patients.

Reliability of post-mortem chart diagnoses of schizophrenia and dementia

The reliability of psychiatric diagnosis has a direct effect on the validity of post-mortem analyses of neuropathological data, yet little is known about the reliability of retrospective diagnostic procedures which rely on review of medical records. In this paper, we report on the reliability of DSM-III-R psychiatric diagnoses assigned by a pool of 8 raters to a set of 106 state hospital charts of elderly, chronic patients who had died while institutionalized and were autopsied. Diagnoses were grouped by general diagnostic class, and Kappa coefficients computed for agreement among raters, as well as for agreement between ultimate consensus diagnoses and those made while subjects were living. Interrater agreement for those diagnoses that occurred most frequently in this sample (e.g. Schizophrenia and Dementia) was excellent, and comparable to the the agreement observed for ratings of live patients. Interrater agreement for less frequently occurring diagnoses (e.g. Mental Retardation, Mood Disorders, other non-Schizophrenic Psychoses) ranged from excellent to poor. We found high agreement between our rates diagnoses and those assigned by state hospital personnel while patients were living, although post-mortem review produced lower rates of diagnosis of both schizophrenia and Alzheimer-type dementias. Overall, results suggest that the reliability of chart review diagnosis is comparable to that obtained from interviews of live patients when experienced raters are used and diagnostic base rates are high enough to produce stable estimates of reliability.

Radiation exposure to human trachea from xenon-133 procedures

The general dosimetry of 133Xe for human studies is well documented, but the resultant radiation exposure to tracheal tissue is poorly known. This organ is of central relevance because the tracer is primarily eliminated through exhalation.

METHODS

We report actual 133Xe concentrations in respiratory air during measurement of regional cerebral blood flow (rCBF), when the tracer is administered both by inhalation and intravenous injection. Data were collected from 102 patients, with equal gender representation and an age range of 18-82 yr. Most of the patients had subarachnoid hemorrhage or Alzheimer's disease or were normal control subjects. Average administered doses were 18 +/- 4 mCi by inhalation and 15 +/- 3 intravenously.

RESULTS

We found average respiratory concentrations of about 1.80 mCi/liter during a 1-min inhalation and 0.74 mCi/liter following intravenous injection of standard doses. These activities drop rapidly: average respiratory concentrations during the second minute are 0.70 mCi/liter for inhalation and 0.19 mCi/liter for intravenous injection and reach negligible levels thereafter. We calculate that the tracheal absorbed dose from 133Xe procedures is approximately 28 mrad following inhalation and about 11 mrad following intravenous injection. These values reflect the full 11-min exposure, but most of the activity is only present initially.

CONCLUSION

These values will agree with previous estimates and indicate an excellent safety margin.

Intellectual decline predicts the parietal perfusion deficit in Alzheimer's disease

The pathophysiology of Alzheimer's disease may be reflected more in an individual's decline from premorbid levels of functioning than in current measures of absolute severity. To test this hypothesis, we computed an index of intellectual decline for individual patients and examined its relationship to Alzheimer's disease-related functional brain abnormalities.

METHODS

We studied 27 patients with Alzheimer's disease diagnosed by ADRDA-NINCDS criteria. We used patient demographics and published formulas to construct estimates of premorbid Wechsler Adult Intelligence Scale (WAIS-R) IQs for each subject in the sample and used a current IQ assessment to estimate the decline in IQ that occurred during the disease for each subject. Cortical perfusion was quantified by the planar 133Xe regional cerebral blood flow (rCBF) technique. The characteristic abnormality in parietal cortex was expressed by the parietal index (PI).

RESULTS

Over the estimated disease duration of 3.8 +/- 2.2 yr, the full-scaled IQ declined by an estimated 28.0 +/- 15.5 points. The current PI was in turn well correlated with the IQ decline (r = 0.66; p < 0.001). This association was linear and stronger than those with other, more common measures of current severity. A multiple stepwise regression analysis suggested that IQ decline alone accounted for the variance in PI related to clinical deterioration. Actual images showed a mild blood flow deficit in patients with the smallest estimated IQ declines but deep and extensive lesions in patients with large declines.

CONCLUSION

These results suggest that the decline from the premorbid baseline, rather than current level of functioning, best predicts the extent of brain damage reflected in the rCBF abnormality, a finding independent of demographic variance.

Cerebral single-photon emission computed tomography abnormalities in human immunodeficiency virus type 1-infected gay men without cognitive impairment

OBJECTIVE

To determine whether technetium Tc99m exametazime single-photon computed emission tomography (SPECT) can distinguish gay human immunodeficiency virus (HIV)-positive subjects, both with and without mild cognitive impairment, from gay HIV-negative control subjects.

DESIGN

Twenty HIV-positive subjects (12 without cognitive impairment and eight with mild cognitive impairment) and 10 HIV-negative subjects underwent neurological, neuropsychological, magnetic resonance imaging, and technetium Tc 99m exametazime SPECT examinations.

SETTING

Subjects were recruited from a natural history study of gay men with HIV infection.

PATIENTS

Subjects from the cohort who had previously participated in a magnetic resonance imaging study were selected for the SPECT study.

MAIN OUTCOME MEASURES

The SPECT scans were rated as abnormal if focal defects, confirmed by a horizontal profile analysis, were seen.

RESULTS

Sixty-seven percent of HIV-positive subjects without cognitive impairment, 88% of HIV-positive subjects with mild cognitive impairment, and 20% of HIV-negative subjects had abnormal SPECT scans (P < .05 for both HIV-positive groups when each group was compared with HIV-negative subjects).

CONCLUSION

Compared with gay HIV-negative control subjects, focal SPECT defects are seen with an increased frequency in HIV-positive gay men without cognitive impairment and in HIV-positive gay men with mild cognitive impairment.

Regional cerebral blood flow in mood disorders: IV. Comparison of mania and depression

Cortical regional cerebral blood flow (rCBF) was assessed in minimally medicated, relatively young adults in episodes of either acute mania (n = 11) or major depression (n = 11) and in matched normal control subjects (n = 11), using the 133xenon inhalation method, under eyes-closed, resting conditions. The three groups were equivalent in global CBF. Both patient groups showed significant reductions of rCBF in anterior cortical areas and reduction of the normal anteroposterior gradient. In addition, there was evidence of abnormal, albeit similar, patterns of flow lateralization on a regional basis in both clinical groups compared with normal subjects. An exploratory analysis revealed preliminary evidence of rCBF differences between the clinical groups, localized to the inferior frontal cortex. Otherwise, the evidence in this study suggests that young adult manic and depressed patients are predominantly similar in cortical rCBF parameters.

Dementia associated with bilateral carotid occlusions: neuropsychological and haemodynamic course after extracranial to intracranial bypass surgery

A 55 year old man with bilateral internal carotid and unilateral vertebral artery occlusions presented subacutely with profound behavioural and cognitive changes featuring frontal lobe deficits. Neuropsychological testing showed severe cognitive impairment compatible with dementia. Anatomical imaging showed only a small right superior frontal infarction. Cerebral blood flow was severely reduced, with profound hypofrontality and limited hypercapnic reactivity, and cerebral metabolism was reduced primarily in the medial frontal lobes. After right sided extracranial to intracranial cerebral bypass surgery, both flow and metabolism improved, as did behavioural and neuropsychological deficits. Perfusion insufficiency from bilateral carotid occlusions, with secondarily reduced metabolism in the frontal zones bilaterally, may be an unusual cause of a reversible frontal dementia syndrome.