Pathological determinants of the transition to clinical dementia in Alzheimer's disease

The authors developed multivariate models to examine the association between Clinical Dementia Rating (CDR) scale scores and the spatial distribution of paired helical filament tau (PHF-tau) pathology. Severity of tauopathy was examined in 14 cortical regions of interest (ROIs). Classification trees were used to test the independent hierarchical contributions of each ROI to dementia. Multiple-regression and cluster analyses were performed to determine the relative contributions of select ROIs to dementia. Dementia (CDR > or = 1) was modeled as a dichotomous variable. Autopsy material was obtained from 124 demented and nondemented elderly patients. All ROIs except the hippocampus made significant contributions to dementia. However, they were not independent. In multivariate models, only a single step (Step 7 in a hierarchical progression), which contained four ROIs, contributed significantly to dementia. A classification tree resulted in a single decision split, suggesting that only Step 7 ROIs need be considered. A total of 89.4% of the cases were correctly classified (p < .0001). Twelve discrepant cases all had superimposed vasculopathy that might also have affected the function of Step 7 ROIs. The transition to clinical dementia was associated with the presence of tauopathy in A9/10, A22, A23, and A39. Animal studies suggest that these represent a single distributed cortical network focusing on prefrontal regions that provide "executive control" over complex goal-directed behaviors. A22, A23, and A39 provide major afferents to other frontal systems and have previously been implicated in very early clinical Alzheimer's disease.

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.

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

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 EXIT25's 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.

Executive cognitive impairment: a novel perspective on dementia

In 1994 the American Psychiatric Association added impairment of executive control functions (ECF) to its list of cognitive domains that should be considered in the assessment of dementia. This recommendation has not been widely implemented. None the less, there is growing evidence that ECF impairment is common, strongly associated with disability and functional decline, and not well detected by traditional dementia screening tests. This article reviews the implications of ECF for the epidemiology of dementia. The total number of dementia cases may be much greater than previously thought and we are likely to be selectively missing cases with reversible causes of ECF impairment.

The use of herbal alternative medicines in neuropsychiatry. A report of the ANPA Committee on Research

Growing numbers of people throughout the United States (40% in 1998) are using various forms of alternative therapies. A MEDLINE literature search of journals from the past three decades and an Internet database query were performed to determine the types and frequency of alternative therapies used, with special attention given to the herbal medicines used in neuropsychiatric disorders. Clinical effects, mechanisms of action, interactions, and adverse reactions of the herbal treatments are detailed. Objective controlled trials will be needed to establish safety and efficacy of herbal supplements. Knowledge of the properties of these therapies can improve the care of neuropsychiatric patients.

Correlates of disability among elderly retirees with "subclinical" cognitive impairment

BACKGROUND

We assessed the effects of impaired Executive Control Function (ECF) on Instrumental Activities of Daily Living (IADL) and level of care among noninstitutionalized elderly retirees with "subclinical" cognitive impairment.

METHODS

Subjects (N = 561; age 78.2 +/- 5.0 years) were residents of a single, 1,500 bed, continuing care retirement community. Subjects were examined for cognitive impairment using the Executive Interview (EXIT25), Mini-Mental State Examination (MMSE), and an executive clock-drawing task (CLOX). The CLOX is divided into executively sensitive (CLOX 1) and simple constructional (CLOX2) subtests.

RESULTS

Residents in congregate high-rises (n = 301) differed significantly from those in independent-living apartments (n = 260) with respect to age, gender, percent living alone, EXIT25, CLOX1, MMSE, and CLOX2 scores (all p < .03). Only differences in ECF measures persisted after adjusting for age and living alone (p < .004). The EXIT25 (p < .006) and CLOX2 (p = .02) were associated with the use of prostheses. The differences in EXIT25 scores persisted after adjusting for level and living alone (p = .01). All instruments distinguished residents with impairment in IADLs. However, only CLOX2 (p < .001), EXIT25 (p < .001), and age (p < .001) made significant independent contributions.

CONCLUSIONS

ECF has statistically significant effects on level of care and IADL impairment, even among noninstitutionalized retirees. This emergent disability is not well detected by traditional global cognitive measures. Evaluation and treatment may be delayed unless ECF measures are employed.

Executive control function: a rational basis for the diagnosis of vascular dementia

Problems with diagnostic criteria for vascular dementia (VaD) stem from the inadequacy of the current dementia concept, a paradigm based on amnestic and other cortical deficits typical of Alzheimer disease (AD). However, most cases of VaD are due to subcortical lesions such as Binswanger-type periventricular white matter ischemia, or strokes causing decreased frontal activation and diaschisis-mediated cerebral hypoperfusion. We propose a new definition of dementia based on executive dysfunction and a formal assessment of executive control functions (ECF) for the diagnosis of VaD. The instruments proposed are the rapid screening executive clock-drawing task (CLOX; Royall et al. J Neurol Neurosurg Psychiatry 1998;64:588-94), and the more comprehensive Executive Interview Test (EXIT25; Royall et al. J Am Geriatr Soc 1992;40:122-6). Extensive application of these tests in elderly subjects in retirement communities has shown that both are brief, simple to administer, and more sensitive case-finding tools for cognitively impaired individuals than the Mini-Mental State Examination (MMSE). These three tests (CLOX, EXIT25, MMSE) accurately separate nondemented subjects from those with cortical or subcortical (frontal system) dementias. In addition, for controlled clinical trials of VaD, formal evaluation of motor and frontal sphincter functions--usually not considered part of the dementia syndrome--should also be included. Evaluation of gait and falls, timed-walk, manual dexterity, timed finger-tapping, and frontal bladder control (urge incontinence and nocturia) should improve determination of functional status and disability, and more accurately measure the effects of potential therapies.

Clock drawing is sensitive to executive control: a comparison of six methods

We examined six clock-drawing task (CDT) scoring systems relative to the Executive Interview (EXIT25, a measure of Executive Control Function [ECF]) and the Mini-Mental State Exam (MMSE). Subjects included n = 33 National Institute of Neurological, Communicative Disorders, and Stroke "probable" Alzheimer's disease (AD) cases and n = 52 independent living controls. AD cases and controls differed on the EXIT25, MMSE, and all CDTs. All CDTs were significantly correlated with the EXIT25 (ranging from r = .56 to r = .78). These associations generally persisted after adjusting for Age, Education, and MMSE scores. In backwards stepwise linear multivariate regression models, only CLOX: An Executive Clock-Drawing Task scores contribute significantly to EXIT25 scores (R2 = .68) and MMSE scores (R2 = .72). Clock drawing draws upon both executive and general cognitive resources. CLOX explains incrementally more variance in ECF than other CDTs.

Pharmacologic efficacy in neuropsychiatry: a review of placebo-controlled treatment trials. A report of the ANPA Committee on Research

Psychiatric disorders frequently compound the disability and complicate the management of neurologic conditions. These disorders result in increased morbidity for the person afflicted, stress for the caregiver, and financial burden. This study reviews the randomized double-blind placebo-controlled pharmacologic treatment trials of psychosis, depression, anxiety, and agitation in neurologic conditions from 1966 to 1998. Ten studies involving psychosis, 13 involving depression, and 20 involving anxiety-agitation meeting the committee's criteria were identified. Relatively few randomized double-blind placebo-controlled pharmacologic treatment trials of psychiatric disorders complicating neurologic disease have been conducted. These trials do not strongly support one specific pharmacologic approach to treatment. Further study of newer psychotropic agents, augmentation strategies, and novel use of other agents may help improve the treatment of psychiatric disorders observed in patients with neurologic disease.

Frontal systems impairment in major depression

Recent studies point to the importance of frontal systems in the control of complex behavior. Because major depression affects the same systems the considerable overlap between some so-called "depressive symptoms" and the behavioral sequelae of frontal lobe brain damage can be explained. In other mental disorders, functional outcomes are closely related to frontal system impairment. Frontal deficits, rather than mood disturbance, may explain the disability of depressed patients. This should cause doctors to reconsider their approach to depression. Treatment for the cognitive aspects of depression may be needed to ensure improvement in functional domains.

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.

DESIGN

Multivariate regression and discriminant modeling.

SETTING

A single Continuing Care Retirement Community (CCRC) in San Antonio, Texas.

PARTICIPANTS

A total of 107 older retirees (mean age = 83.7+/-7.2 years), including 17 community-dwelling, well, older controls and 90 CCRC residents. CCRC subjects represented a convenience sample of consecutive referrals for geropsychiatric assessment. Sixty-one subjects resided at a noninstitutionalized level of care, and 46 were institutionalized.

MEASUREMENTS

Tests of ECF (the Executive Interview (EXIT25)), general cognition (the Mini-Mental State Examination (MMSE)), mood (the Geriatric Depression Scale short-form (sGDS)), problem behavior (the Nursing Home Behavior Problem Scale (NHBPS)), physical disability (the Cumulative Illness Rating Scale (CIRS)), age, gender, years of education, and the number of prescribed medications were studied.

RESULTS

All variables except gender and education varied significantly across level of care. Four variables made significant independent contributions; EXIT25 score (r2 = .48, P< .001), medication usage (partial r2 = .11, P<.001), sGDS score (partial r2 = .06, P = .001), and problem behavior (partial NHBPS r2 = .04, P<.04). These variables accounted for 69% of the total variance in level of care (R2 = .69; F (df 7,99) = 32.1, P<.001). A discriminant model based on the number of prescribed medications, EXIT25, sGDS, and NHBPS scores classified 83.2% of cases correctly (Wilke's lambda = .50, F(5,101) = 20.1; P<.001). The MMSE enters but fails to contribute significantly, independent of the other variables. Age and CIRS scores fail to enter.

CONCLUSIONS

Cognitive (particularly ECF) impairment contributes most to the observed variance in level of care received by older retirees in this CCRC. In contrast, markers of general cognition, depression, and physical illness contributed relatively little additional variance. ECF is not detected well by traditional cognitive measures and must be sought by specific tests. Further study is needed to replicate these findings in other populations.

Neuropsychiatric correlates and treatment of lenticulostriatal diseases: a review of the literature and overview of research opportunities in Huntington's, Wilson's, and Fahr's diseases. A report of the ANPA Committee on Research. American Neuropsychiatric Association

This report reviews clinical neuropsychiatric findings and opportunities for research in Huntington's, Wilson's, and Fahr's diseases. Consistent, systematic methodology is lacking among neuropsychiatric studies in these lenticulostriatal diseases. Systematic cross-sectional and longitudinal assessments are needed to ascertain the prevalence of psychiatric disorders as a function of disease course. Preliminary synthesis of existing data suggests the following heuristic relationships in these diseases: depression with parkinsonian states; personality changes with caudate or putamen disease; psychosis, impulsivity, and sexual disorders with caudate disease; dementia and mania with caudate and pallidal diseases; and compulsions with pallidal disease. Correlation of neuropsychiatric findings with disease stage, clinical signs, and radiologic, metabolic, physiologic, and pathologic markers of disease will add to our understanding of these conditions.

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; R2=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; R2=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.

The clinician-scientist in neuropsychiatry: a position statement from the Committee on Research of the American Neuropsychiatric Association

Neuropsychiatric research seeks to improve the lives of patients with brain-based behavioral disturbances. There has been dramatic progress in diagnosis and treatment of neuropsychiatric disorders, and progress in neuroscience and biotechnology promises further success. Paradoxically, recent trends threaten to erode this progress. In this environment, neuropsychiatric clinician-scientists must advocate for the importance of research. This position statement defines neuropsychiatric research, describes current challenges to the neuropsychiatric clinician-scientist, summarizes research opportunities, describes how future neuropsychiatric clinician-investigators should be trained, and makes recommendations for promoting neuropsychiatric research.

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. Alzheimer's 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.

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 Alzheimer's 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.