Roderick K. Mahurin

Decreased cerebral blood flow precedes multi‐infarct dementia, but follows senile dementia of Alzheimer type

A 7-year prospective study among 181 neurologically normal elderly volunteers (mean age, 70.6 years) revealed an incidence of 3.3%, or 0.47% new cases per year, for Alzheimers disease (SDAT) and 5.5%, or 0.78% new cases per year, for multi-infarct dementia (MID). The unusually high incidence of MID is considered to reflect preselection of a large percentage of volunteers (48.6%) with risk factors for (but without symptoms of) atherothrombotic stroke. Of 88 volunteers at risk of stroke, 11.4% developed MID within 7 years. In MID patients, cerebral blood flow (CBF) values began to decline around 2 years before onset of symptoms, while in SDAT patients, CBF levels remained normal until symptoms of dementia appeared; thereafter, CBF declined rapidly.

Insight for impairment in independent living skills in Alzheimer's disease and multi-infarct dementia

Dementing diseases cause a deterioration in the capacity for independent living skills (ILS). The present study investigated the level of insight in ILS impairment in 12 Alzheimers disease (AD) patients, 12 multi-infarct dementia (MID) patients, and 12 normal elderly controls, using two different measurement techniques: informant report and patient self-report. Pairwise comparisons at the .05 level revealed a significantly greater loss of insight for ILS impairment in AD patients as compared to both controls and MID patients. Additional analyses revealed that loss of insight, operationally defined as the discrepancy between informant report and patient self-report, was not significantly related to age, education, mental status, or level of depression, but was significantly related to degree of caregiver burden. These results indicate that intervention strategies are needed that take into consideration the level of patient insight for ILS impairment, as well as the caregivers perception of the patients capabilities and the degree of burden experienced by the caregiver.

Age-Related Reductions in Cerebral Vasomotor Reactivity and the Law of Initial Value: A 4-Year Prospective Longitudinal Study

A group of 51 neurologically normal, middle-aged and elderly volunteers (aged 35–86 years; mean age 63.24 years) with and without risk factors for stroke were given annual tests of cerebral vasomotor reactivity to assess any changes in the cerebral vascular capacitance associated with advancing age that might alter cerebral vasomotor reactivity. Cerebral vasomotor reactivity was estimated as the difference in bihemisphere gray matter CBF measured by the 133Xe inhalation method in the steady state breathing room air, followed by a second measurement during inhalation of 100% oxygen. There were significant and progressive reductions in cerebral vasomotor reactivity during the 4-year longitudinal study. Positive linear correlations were apparent between initial steady-state mean bihemisphere gray matter CBF levels and degrees of vasomotor reactivity, suggesting that the Law of Initial Value plays an important role. This should be borne in mind when analyzing scores of cerebral vasomotor reactivity. In the present communication, analysis of covariance was used to correct for influences of initial CBF levels on vasomotor responses tested while breathing pure oxygen.

Chronometric analysis: Clinical applications in aging and dementia

Reaction time (RT) measurement offers increased clinical precision in the neuropsychological assessment of age‐related dementia. Chronometric procedures are generally well accepted and reliable and demonstrate both diagnostic and functional sensitivity to cognitive decline. This review focuses on the use of RT for the evaluation of patients with Alzheimers disease (AD) and introduces the timed card‐sorting task as a convenient measure of response time for use in the clinical setting. Methodological issues and hypothesized attentional mechanisms underlying RT slowing in AD are discussed.

Choice Reaction Time Modifiability in Dementia and depression

The effects of cognitive impairment resulting from either dementia of the Alzheimer type (DAT) or major depression (pseudodementia) on choice reaction time were examined in two conditions hypothesized to influence group performance selectively. Elderly controls had shorter reaction times than depressed patients who, in turn, were faster than dementia patients in the standard choice reaction time test. Elderly control and depressed subjects responded more quickly under conditions designed to reduce task demands. However, no effect was detected for DAT patients, presumably due to the neural constraints imposed on cognitive functioning in dementia. These results highlight the different etiologies for the intellectual decline in dementia and pseudodementia.