Faculty Bibliography

In order to determine the relationship between cognitive dysfunction and motor behavior in older adults, 41 cognitively normal elderly (NL), 25 cases exhibiting mild cognitive impairment (MI), and 25 patients with mild Alzheimer's disease (AD) were examined using a broad array to motor/psychomotor and cognitive tests. Relative to the NL group, MI individuals (at risk for future decline to AD) performed worse on tasks involving fine and complex motor function (e.g., tracking and manual dexterity). AD patients also exhibited motor dysfunction on tasks assessing relatively more rudimentary motor control. Motor tasks were able to distinguish NL vs MI and NL vs mild AD individuals as effectively as cognitive tests of memory and language. These results indicate that motor impairment is an important aspect of cognitive decline in older adults. Motor/psychomotor assessments may be comparably sensitive to traditional tests of cognitive function in identifying persons affected by the earliest stages of AD pathology

To determine the association between cognitive dysfunction and motor behavior in older adults, 41 cognitively normal elderly (NL), 25 nondemented patients exhibiting mild cognitive impairment (MI) and at risk for future decline to dementia, and 25 patients with mild (early) Alzheimer's disease (AD) were examined using a wide array of motor/psychomotor and cognitive assessments. The three groups were recruited from an aging and dementia research center and were composed of well-characterized physically healthy volunteers, with similar ages and gender distributions. The outcome measures included 16 motor/psychomotor tests categorized a priori into gross, fine, and complex, as well as eight cognitive tests of memory and language. Relative to the NL group, MI individuals performed poorly on cognitive, fine, and complex motor measures but not on gross motor tests; AD patients performed worse on cognitive and all motor domains. Differences in complex motor function persisted after adjustment for performance on cognitive and on less complex motor tests. Classification analyses showed similar accuracies in discriminating NL from MI and NL from AD cases for both complex motor (79% and 92% accuracy, respectively) and cognitive tests (80% and 93% accuracy, respectively). Less complex motor tests produced poorer accuracies. Among nondemented subjects, education correlated with several cognitive scores but no motor scores. These results indicate that motor impairment is an important aspect of cognitive decline in older adults. Motor/psychomotor assessments were found to be comparably sensitive to traditional tests of cognitive function in identifying persons affected by the earliest stages of AD pathology and may improve identification of at-risk nondemented elderly, especially among diversely educated individuals

Because cognitive impairment is the central, defining symptom of Alzheimer disease, cognitive assessments commonly are used as primary or secondary measures of outcome in Alzheimer disease research. The authors review the cognitive functions that decline in this neurodegenerative disease and summarize the necessary features of appropriate cognitive performance tests. The characteristics, strengths, and weaknesses of the major cognitive batteries employed as outcome measures in Alzheimer disease research are reviewed. Finally, the recent contributions to the development of cognitive measures by the Alzheimer's Disease Cooperative Study are presented briefly, followed by discussion of some critical issues for future test development

Hippocampal formation (HF) atrophy, although common in normal aging, has unknown clinical consequences. We used MRI to derive HF size measurements at baseline on 44 cognitively normal older adults entering a longitudinal study of memory function (mean age = 68.4 years, mean follow-up = 3.8 years). Only one subject became demented at follow-up. Multiple regression analyses controlling for age, gender, education, and diffuse cerebral atrophy revealed that HF size significantly predicted longitudinal change on memory tests previously found sensitive to decline in normal aging. These results indicate HF atrophy may be a risk factor for accelerated memory dysfunction in normal aging

Age-Associated Memory Impairment (AAMI) and the broader DSM-IV classification Age-Related Cognitive Decline (ARCD) both represent the well-documented phenomenon of declining cognitive performance with age. Objections to AAMI/ARCD often stem from inappropriate adherence to the ''disease model'' instead of recognizing that cognitive decline is a common behavioral consequence of brain aging. One unsolved problem, however, is the difficulty in assessing individual decline without longitudinal data. Individuals with Mild Cognitive Impairment (MCI) are 3. heterogeneous group whose cognitive performance is between that of individuals with ARCD and early Alzheimer's disease (AD). Research confirms that MCI cases are at increased risk for developing AD within several years, and that cognitive and in vivo brain measures may help identify individuals at risk for accelerated age-associated decline or developing AD. Both ARCD and MCF are appropriate targets for pharmacologic interventions that might slow the rate of decline or delay the onset of AD

Alzheimer's disease (AD) is associated with an increased mortality in comparison with aged control populations. The relationship between the clinical and the temporal course of AD has not been well studied over significant intervals. Community-residing patients with probable AD (N = 103, 42 men, mean age = 70.2 +/- 8.0 years) were studied at baseline on demographic and clinical variables, including measures of global deterioration (Global Deterioration Scale; GDS), mental status and cognition (e.g., Mini-Mental State Examination; MMSE), and functional impairment (Functional Assessment Staging; FAST). Baseline characteristics included a GDS range of Stage 4, 5, or 6 (38.8%, 39.8%, and 21.4%, respectively) and a mean MMSE score of 15.4 +/- 5.6. The mean follow-up interval was 4.6 +/- 1.4 years. Follow-ups were done blind to baseline measures and when necessary were conducted in residential and nursing home settings. Of locatable subjects (n = 95, 92%), 30 (31.6%) were decreased. Survivors (n = 65) had a mean GDS stage of 6.2 +/- 0.9 and a mean MMSE score of 5.1 +/- 6.9; 51% had MMSE scores of 0. Increased age and male gender, but not baseline clinical dementia variables, increased the risk of death (ps < .01). Change in clinical variables correlated significantly with time elapsed (r = .32, p < .05, for MMSE change, to r = .48, p < .001, for GDS change). Significant variance in temporal change (i.e., time elapsed) was accounted for by change in two of the five clinical measures studied (i.e., GDS and FAST; multiple r = .53). The results support previous estimates of mean duration of the GDS and FAST stages. For subjects with probable AD followed over approximately 5 years, clinical variables changed significantly over time in survivors. However, the majority of temporal variance in the course of AD remains unexplained

To address the issue of mild, moderate, and severe Alzheimer's disease (AD), it is necessary to initially establish some agreement on terminology. In recent decades, these terms have frequently been defined using screening instrument scores with measures such as the Mini-Mental State Examination (MMSE). There are many problems with this approach, perhaps the most salient of which is that it has contributed to the total and tragic neglect of patients with severe AD. An alternative approach to the classification of AD severity is staging. This approach has advanced to the point where moderately severe and severe AD can be described in detail. Procedures for describing this previously neglected latter portion of AD have recently been extensively validated. Staging is also uniquely useful at the other end of the severity spectrum, in differentiating early aging brain/behavior changes, incipient AD, and mild AD. Temporally, with staging procedures, it is possible to track the course of AD approximately three times more accurately than with the MMSE. The net result of the advances in AD delineation is that issues such as prophylaxis, modification of course, treatment of behavioral disturbances, loss of ambulation, progressive rigidity, and the development of contractures in AD patients can now be addressed in a scientifically meaningful way that will hopefully bestow much benefit in AD patients and those who care for them

With advancing age, the periventricular and subcortical white matter becomes susceptible to a heterogeneous assortment of tissue alterations that cannot be easily categorized in terms of traditionally defined neuropathologic disease. These alterations, which appear radiolucent on CT and hyperintense on T2-weighted MR imaging, are more common in patients with chronic hypertension and perhaps other microvascular arteriosclerotic risk factors. Examination of the affected tissue reveals a spectrum of histologic change that is graded with respect to pathologic severity. The majority of the alterations are of low histopathologic grade and exert minimal clinical effects. Frequently observed microscopic changes include dilated perivascular (Virchow-Robin) spaces, mild demyelination, gliosis, and diffuse regions neuropil vacuolation. Associated clinical abnormalities, when present, are usually confined to deficits of attention, mental processing speed, and psychomotor control. These deficits may often be demonstrable only through neuropsychologic testing. There is some evidence that the cognitive symptoms of AD may be exacerbated by the concomitant presence of these white matter alterations, but an etiologic link between AD and radiographically detectible white matter changes remains speculative. Occasionally, histologically severe white matter lesions may occur that result in dementia and focal neurologic impairment. These lesions are characterized by extensive arteriosclerosis, diffuse white matter necrosis, and lacunar infarction; affected patients may receive a diagnosis of Binswanger's disease or subcortical arteriosclerotic encephalopathy. Nevertheless, severe ischemic white matter pathology of this type is uncommon as an explanation for serious neurologic dysfunction, and clinicians must carefully weigh other categories of neuropathology before making a diagnosis of Binswanger's disease. Alternative diagnostic considerations include neurodegenerative illnesses such as AD, cerebral infarction, neoplasm, and other forms of white matter pathology such as those due to infection, inflammation, a primary demyelinative condition, or metabolic leukodystrophy