Cerebral hemodynamics and cognitive impairment: baseline data from the RECON trial

OBJECTIVE

To determine whether unihemispheral hemodynamic failure is independently associated with cognitive impairment among participants in the National Institute of Neurological Disorders and Stroke-sponsored, multicenter, randomized clinical trial, Randomized Evaluation of Carotid Occlusion and Neurocognition (RECON).

METHODS

Forty-three patients were randomized into RECON after recent symptomatic carotid artery occlusion and asymmetrically increased oxygen extraction fraction (OEF) by PET (OEF ratio >1.13), indicating stage II hemodynamic failure on the side of occlusion. The PET-positive patients were compared with 28 RECON-enrolled patients who met all clinical and radiographic inclusion/exclusion criteria but had no OEF asymmetry. A multivariable regression compared patients with PET OEF >1.13 or ≤1.13, stratifying by TIA vs. stroke as the qualifying event. The dependent variable was a composite neurocognitive score derived from averaging age-normalized z scores on a test battery that included global and internal carotid artery (ICA) side-relevant hemisphere-specific tests.

RESULTS

There were no differences in demographic, clinical, or radiologic characteristics between the PET-positive and PET-negative patients except for PET OEF asymmetry. The unadjusted average neurocognitive z score was -1.45 for the PET-positive and -1.25 for the PET-negative patients, indicating cognitive impairment in both groups but no difference between them (p = 0.641). After adjustment for age, education, side of occlusion, depression, and previous stroke, there was a significant difference between PET-positive and PET-negative patients among those with TIA as a qualifying event (average z score = -1.41 vs. -0.76, p = 0.040). Older age and right ICA side were also significant in this model.

CONCLUSION

Hemodynamic failure is independently associated with cognitive impairment in patients with carotid occlusion. This finding establishes the physiologic parameter upon which the extracranial-intracranial bypass will be tested.

Klüver-Bucy syndrome after bilateral selective damage of amygdala and its cortical connections

Isolated symmetric damage to the amygdala and their cortical connections occurred in an individual following cancer treatment. The lesions were imaged after reversal of hyponatremia. The patient displayed marked behavioral changes including visual agnosia, hypersexuality, hyperorality, a tendency to react to every visual stimulus, and memory deficits. The cluster of neurobehavioral symptoms is similar to previously reported accounts of Klüver-Bucy syndrome and suggests the importance of bilateral amygdala involvement in these behavioral changes.

Pattern of neurobehavioral deficits associated with interferon alfa therapy for leukemia

We evaluated the neuropsychological and personality profiles of 25 patients with chronic myelogenous leukemia treated with interferon alfa (IFN-alpha). This group of persons performed well below expectation on tests of cognitive speed, verbal memory, and executive functions. Personality changes included depression, increased somatic concern, and stress reactions. A control group of leukemia patients not treated with IFN-alpha had significantly better cognitive speed and mood. The pattern of cognitive and personality changes in patients receiving IFN-alpha is highly suggestive of frontal-subcortical brain dysfunction.

Prospective studies of cerebral perfusion and cognitive testing among elderly normal volunteers and patients with ischemic vascular dementia and Alzheimer's disease

To compare longitudinal changes of cerebral perfusion (CBF) and cognitive status in two common forms of dementia in the elderly, 42 patients with ischemic vascular dementia (IVD), 44 patients with dementia of the Alzheimer type (DAT), and 120 elderly normal volunteers were evaluated prospectively over a mean interval of 3.35 years. Subjects were at least age sixty, (mean age 71.1). Mean bihemispheric cerebral blood flow and cognitive test scores of control subjects were significantly higher than those of both demented groups at entry and remained so. After adjustment for initial CBF, course over time was similar for all groups. Group variability was similar for CBF but not for cognition. Both IVD and DAT patients were more variable than controls but similar to each other. Throughout, DAT patients showed greater cognitive impairments than IVD patients. Cognitive impairments stabilized among IVD patients treated by control of risk factors, antiplatelet or anticoagulant therapy but declined progressively among DAT patients.

Analysis of familial and individual risk factors among patients with ischemic vascular dementia and Alzheimer's disease

The purpose of this study was to determine relative contributions of first-degree familial and individual risk factors to clinical manifestations of two major age-related dementias. The authors interviewed 183 patients with dementia of the Alzheimer's type (DAT) and 137 patients with ischemic vascular dementia (IVD) together with family members and caregivers. Information was also obtained from medical records and collateral sources as required. Risk factor data within a predictive model for differentiating the two dementias were evaluated. There was a greater incidence of family history of degenerative and dementing neurologic disorders in DAT than in IVD. Both groups were equivalent for family histories of cerebrovascular disease. Despite familial equivalence, patients with IVD had a greater individual incidence of risk factors for cerebrovascular disease. Analysis by gender revealed three observations. Among DAT patients, family history for degenerative and dementing neurologic disorders proved to be significantly greater among women than among men. This risk factor did not, however, predict individual diagnoses for DAT. Women with IVD were more likely to have a family history of cancer than men. Multiple regression analyses revealed that reduced educational levels in women predicted greater liability for IVD than for DAT. Hypertension, heart disease, and diabetes mellitus were all risk factors for IVD, but not for DAT.

CONCLUSIONS

Individual and familial historical data provide useful information concerning identification, pathogenesis, prevention, and treatments for vascular dementia but little predictive information for identifying patients with Alzheimer's disease.

Leuko-araiosis and cerebral perfusion in normal aging

To clarify the incidence, age relationships and pathogenesis of white matter lesions of unknown origin (leuko-araiosis) detected by neuroimaging among normal elderly volunteers, we measured the severity of leuko-araiosis using computerized tomographic (CT) densitometry among 42 healthy self-supporting men and women of different ages, all with normal neurological and cognitive test performance. Results were correlated with local cerebral perfusion using xenon-contrasted CT. The 42 volunteers, who are followed in this laboratory for studies of normal aging, were divided into two groups in order to determine aging effects by an extremes design. One group consisted of 19 adults below age 60 (M = 53.3, SD = 6.0). The index group comprised 23 individuals all over the age of 60 (M = 71.6, SD = 8.7). Leuko-araiosis around the anterior horns of the lateral ventricles (frontal leuko-araiosis) was more severe (p < .01) among the older group, however, occipital leuko-araiosis did not significantly differ between older and younger groups. Cerebral perfusion in frontal, temporal, and parietal cortex was decreased among older compared with younger volunteers (ps < .001, .01, and .05, respectively). Multiple regression analyses disclosed significant and direct relationships between severity of frontal leuko-araiosis and (a) frontal cortical atrophy and (b) reductions of cerebral perfusion within frontal white matter and caudate nucleus. We conclude that cortical atrophy with hypoperfusion and ischemia of frontal white matter play a part in the pathogenesis of frontal leuko-araiosis associated with normal aging and this may be a predictor for later cognitive declines.