Marsha J. Polk

CLOX: an executive clock drawing task

OBJECTIVE To describe a clock drawing task (CLOX) designed to elicit executive impairment and discriminate it from non-executive constructional failure. SUBJECTS 90 elderly subjects were studied (45 elderly and well persons from the independent living apartments of a continuing care retirement community and 45 patients with probable Alzheimer’s disease). The clock drawing performance of elderly patients was compared with that of 62 young adult controls. METHODS Subjects received the CLOX, an executive test (EXIT25), and the mini mental state examination (MMSE). The CLOX is divided into an unprompted task that is sensitive to executive control (CLOX1) and a copied version that is not (CLOX2). Between rater reliability (27 subjects) was high for both subtests. RESULTS In elderly subjects, CLOX subscores correlated strongly with cognitive severity (CLOX1:r=−0.83 v the EXIT25; CLOX2:r=0.85 v the MMSE). EXIT25 and MMSE scores predicted CLOX1 scores independently of age or education (F(4,82)=50.7, p<0.001;R 2 =0.71). The EXIT25 accounted for 68% of CLOX1 variance. Only the MMSE significantly contributed to CLOX2 scores (F(4,72)= 57.2, p<0.001;R 2 =0.74). CLOX subscales discriminated between patients with Alzheimer’s disease and elderly controls (83.1% of cases correctly classified; Wilkes’ lambda=0.48, p<0.001), and between Alzheimer’s disease subgroups with and without constructional impairment (91.9% of cases correctly classified; Wilkes’ lambda=0.31, p<0.001). CONCLUSIONS The CLOX is an internally consistent measure that is easy to administer and displays good inter-rater reliability. It is strongly associated with cognitive test scores. The pattern of CLOX failures may discriminate clinical dementia subgroups.

Declining Executive Control in Normal Aging Predicts Change in Functional Status: The Freedom House Study

Objectives: To assess the contribution of executive control function (ECF) to functional status.

Executive control mediates memory's association with change in instrumental activities of daily living: the Freedom House Study.

Objectives: To assess the relative independent contribution of changes in executive control function (ECF) and memory to changes in functional status.

Executive Dyscontrol: An Important Factor Affecting the Level of Care Received by Older Retirees

OBJECTIVES: To examine the relative contributions of Executive Control Function (ECF), general cognition, mood, problem behavior, physical disability, demographic variables, and the number of prescribed medications to the level of care received by older retirees.

Executive Control and the Comprehension of Medical Information by Elderly Retirees

This study examined the independent contributions of executive control function, general cognition, age, education, and medication usage to the comprehension of medical information. Randomly selected elderly retirees (N = 105) more than 70 years of age completed the Executive Interview (EXIT25), the Mini-Mental State Exam (MMSE), and the Hopkins Competency Assessment Test (HCAT). Cognitive measures were stronger predictors of HCAT scores than age, education, or number of prescribed medications. A discriminant model based on EXIT25 and MMSE scores correctly classified 91% of subjects relative to their HCAT scores. It was concluded that executive impairment is strongly associated with impaired comprehension of medical information. As many as 88% of probable Alzheimers disease patients, 69% of institutionalized elderly retirees, and 49% of noninstitutionalized retirees may be impaired in their ability to comprehend medical information, even when it has been presented well below their educational level.

Severe Dysosmia Is Specifically Associated with Alzheimer-Like Memory Deficits in Nondemented Elderly Retirees

Objectives: To determine whether or not (1) impaired olfactory function is associated with impaired memory on neuropsychological testing in healthy retirees, and if so then (2) whether memory impairment is most consistent with a mesiotemporal rather than frontal system disorder. Methods: 173 independent residents of a continuing care retirement community were studied. Subjects completed the University of Pennsylvania Smell Identification Test (UPSIT) and a battery of both general and specific cognitive measures that included the Mini-Mental State Examination (MMSE) and the Executive Interview (EXIT25). Subjects were examined twice over 3 years. Results: UPSIT performance was normal in 21% and in the ‘anosmic’ range in 25% of subjects. Anosmic UPSIT performance was associated with significantly worse performance on all cognitive tests. However, only short-term verbal memory was independently associated with UPSIT-defined anosmia. This association remained significant after adjusting for the other cognitive and sociodemographic variables. The memory deficits of anosmic subjects were qualitatively consistent with a cortical type (type 1) dementing illness such as Alzheimer’s disease (AD). Over time, UPSIT-defined ‘anosmic’ cases suffered significantly greater declines on both the MMSE and the EXIT25, independently of baseline age, gender and MMSE score. Conclusions: Impaired odor identification in individuals without overt dementia is associated with an AD-like memory impairment and an increased rate of cognitive decline. The comorbid association of these deficits is consistent with the known hierarchical spread of preclinical AD pathology and may be a specific indicator of future clinical AD dementia.

Dementias That Present With and Without Posterior Cortical Features: An Important Clinical Distinction

There are distinct qualitative differences between the dementias that present with and without posterior cortical features. These can be utilized in dementia assessment. This paper reviews the validity and potential utility of a dichotomy based on generalized cortical (Type 1) versus isolated frontal system pathology (Type 2). These syndromes are associated with distinct differentials and problem behaviors. They may also result in different caregiving burdens or treatment responses. Alzheimers disease (AD) is by far the most common cause of the Type 1 syndrome. Type 2 presentations select for potentially reversible non‐AD conditions. Common cognitive screening instruments are insensitive to Type 2 cases. However, the Type 1/Type 2 distinction can be made reliably using qualitative clinical rating scales. We will review these instruments and discuss their application in clinical settings.

Misclassification is likely in the assessment of mild cognitive impairment.

We estimated the relative frequency of isolated memory impairment versus isolated and comorbid impairment in executive control function (ECF). One hundred and ninety-three noninstitutionalized residents of a single Comprehensive Care Retirement Community (mean age 79.2 years) were investigated. The subjects were tested with multiple measures of memory and ECF. Test scores were standardized to minimize scaling effects. ‘Impairment’ was defined as performance ≤1.5 standard deviations below the mean for the entire sample (i.e., a z score ≤–1.5). Disability was estimated as the sum of self-reported activities of daily living and instrumental activities of daily living. The cognitive test performance was significantly associated with functional impairment, independently of age. ECF and memory measures were significantly intercorrelated. Both were significantly and independently associated with disability ratings. 6–10% of the subjects had memory impairment; 25–35% of the memory-impaired subjects had comorbid ECF impairments. An additional 4–7% of the subjects had isolated ECF impairment. A significant fraction of the cases otherwise meeting the criteria for ‘mild cognitive impairment’ may have comorbid ECF impairment. This raises the issue of whether they might be more properly classified as ‘demented’. In addition, isolated ECF impairment may affect almost as many persons as isolated memory impairment. Isolated ECF impairment is not consistent with the natural history of preclinical Alzheimer’s disease, suggests other conditions, and can be disabling, independently of age and/or memory loss.

Depressive symptoms predict longitudinal change in executive control but not memory

Depression in non‐demented persons has been identified as a possible risk factor for incident Alzheimers disease (AD).

Frontal MRI findings associated with impairment on the Executive Interview (EXIT25).

Abstract We examined the association between the Executive Interview (EXIT25), a bedside measure of executive control, and regional magnetic resonance imaging (MRI) pathology among 52 consecutive geriatric patients presenting to a university dementia assessment clinic. Left frontal (p < .002), left medial (p < .03), right frontal (p < .02), and right medial (p < .02) cortical lesions significantly worsened EXIT25 scores, even after adjusting for age, global cognitive impairment (on the Mini-Mental State Examination), and the severity of cortical dementia on the Qualitative Evaluation of Dementia [QED]. The EXIT25s associations with right hemisphere lesions did not persist after adjusting for left frontal lesions. Left posterior lesions did not significantly affect the EXIT25. Similarly, left frontal circuit pathology worsened EXIT25 scores (p < .05). Pathology in left anterior subcortical structures showed a trend (p = .052). EXIT25 scores were not affected by right subcortical pathology, nor by pathology in either hippocampus. We conclude that the EXIT25 is specifically affected by frontal system MRI lesions, particularly on the left. This conclusion is consistent with earlier functional neuroimaging studies associating EXIT25 performance with left mesiofrontal perfusion.