Apolipoprotein E epsilon 4, other risk factors, and course of Alzheimer's disease

BACKGROUND

The epsilon 4 allele of apolipoprotein E (apoE epsilon 4) is associated with late-onset Alzheimer's disease (AD), but its relationship to various aspects of AD has become increasingly unclear. We studied the relationship of apoE genotype in AD to educational attainment, history of heart disease or head injury, age of onset, gender, severity of illness, depression, psychotic symptoms, rate of dementia progression, and time from initial evaluation to nursing home placement.

METHODS

ApoE epsilon 4 genotype was determined for 97 clinically diagnosed AD patients and 61 neuropathologically confirmed cases of AD.

RESULTS

Presence of one or more epsilon 4 alleles occurred in 66% of AD cases as compared with 27% in control subjects (allele frequency was .40 for AD, .15 for control subjects). Among AD subjects there was no significant relationship between epsilon 4 alleles and educational attainment, history of heart disease, head injury, age of onset, severity of illness, depression, history of depression, rate of dementia progression, or time to nursing home placement. Marginal correlations emerged between number of epsilon 4 alleles, and delusions (p = .05) and hallucinations (p = .05). There was a trend toward increased epsilon 4 homozygosity in patients with onset between ages 65 and 70 years.

CONCLUSIONS

We did not find that individuals with one or two apoE epsilon 4 alleles differed significantly in clinical course of AD from those without epsilon 4 except for a trend toward increased psychotic symptoms in the group as a whole and an increase in epsilon 4 homozygosity in patients with reported symptom onset in the late 60s.

A comparison of the Cohen-Mansfield agitation inventory with the CERAD behavioral rating scale for dementia in community-dwelling persons with Alzheimer's disease

In a group of 242 community-dwelling patients with Alzheimer's disease (AD), a longitudinal comparison was made of two caregiver-administered instruments for assessment of behavioral disturbance; the Cohen-Mansfield Agitation Inventory (CMAI) and the CERAD Behavioral Rating Scale for Dementia (BRSD). We examined records of the 206 patients with baseline and 12-month follow-up data for the CMAI and the BRSD who also had tests of cognitive (Mini-mental State; MMSE) and global function (Clinical Dementia Rating; CDR and Functional Assessment Staging; FAST). Among 114 AD subjects, the correlation between total CMAI at baseline and 1 month readministration was 0.83 (p < 0.0001). In the same subjects, stratified into 5 groups by MMSE scores, the correlations between BRSD baseline and 1-month scores ranged from 0.70-0.89 (p < 0.0001). There was high correlation between total scores of both instruments at baseline and 12 months. In addition, all CMAI subscales except Verbally Aggressive correlated significantly with total BRSD score at both time points. At baseline, BRSD subscales for irritability/aggression, behavioral dysregulation and psychotic symptoms and at 12 months, irritability/aggression and behavioral dysregulation correlated with total CMAI scores. Neither scale changed significantly over 1 year, but there was wide individual variation. CMAI and BRSD scores correlated with 1-year change in the FAST, but not with MMSE or CDR (which weighs cognition heavily), suggesting that behavioral disturbance may be more strongly related to ability to manage activities of daily living (executive function) than to other aspects of cognition. The CMAI and BRSD appear to be interchangeable as measures of agitation, with the CMAI possibly more useful for patients who lack language and the BRSD more sensitive to apathy and depression.

Dementia associated with cortical dysplasia

Detailed neuropathologic examination was performed on a 47.5-year-old man with an unusual adult-onset dementing illness. His initial symptoms were those of depression, memory loss, and personality change. He developed progressive cognitive decline with prominent psychiatric symptoms. Seizures began approximately 11 months prior to death and he died 5.5 years after onset of symptoms. Pathologic examination of the brain at autopsy revealed organizing necrosis of the hippocampi, felt to be the result of his seizures. More significant was the finding of widespread microscopic nodular cortical dysplasia. The dysplastic nodules were composed of clusters of abnormal cells with enlarged, pleomorphic, vesicular nuclei, many of which contained nucleoli and had ballooned cytoplasm. There were no mitoses. Cortical dysplasia is most commonly associated with childhood-onset seizures. It has not, to our knowledge, been reported as a cause of dementia. Whether or not the dysplasia was the basis of the patient's dementia is difficult to say with certainty, but we discuss possible pathoetiologic mechanisms of dementia due to cortical dysplasia.

Cortisol secretion and Alzheimer's disease progression

BACKGROUND

Mild hypercortisolemia is a frequent concomitant of Alzheimer's disease (AD). In an effort to ascertain the relationship between serum cortisol concentration (CORT) and disease progression, aging, and survival, we followed 9 persons with AD, ages from 56 to 84 years, from an original cohort of 19 enrollees with serial cognitive testing and CORT determinations.

METHODS

The cognitive instrument was a modification of the Alzheimer's Disease Assessment Scale-Cognitive (mADAS-COG). Serum cortisol determinations were performed at noon, and an Afternoon Cortisol Test (ACT) was used to obtain an estimate of average CORT.

RESULTS

Baseline 12:00 hours CORT but not ACT correlated significantly with the change in mADAS-COG (r = .90, p < .01). ACT levels increased as the mADAS-COG increased over time (p = .037), by 0.156 +/- 0.06 microgram/dL for each one-point increase (indicating greater impairment) in cognitive test score. ACT levels did not increase significantly simply with aging. For the entire cohort of 19 subjects, neither baseline ACT nor 12:00 hours CORT was significantly related to survival.

CONCLUSIONS

Hypercortisolemia in AD appears related to the clinical progression of the disease, but not to aging or length of survival.

Autosomal dominant progressive syndrome of motor-speech loss without dementia

This patient report describes a 68-year-old man with progressive dissolution in motor-speech without concomitant language or cognitive decline, with presumed autosomal dominant inheritance. Motor-speech impairments included marked difficulty in articulating words and in coordinating articulation, phonation, and respiration. Brain imaging results revealed severe focal atrophy of the posterior frontal region extending to the anterior parietal and superior temporal regions bilaterally on structural (MRI) and functional (single photon emission computed tomography) brain imaging studies. The involved neural substrate represented the primary motor cortex, premotor cortex (supplementary motor area), and the postcentral gyrus. Familial history included similar difficulties in his mother, her sister, and his own sister. The isolated involvement of the motor-speech processes alone indicated that this syndrome was distinguishable from progressive aphasia associated with prominent loss of language and from Alzheimer's disease.

Familial dementia due to adult polyglucosan body disease

BACKGROUND

Adult polyglucosan body disease (APBD) is a rare disorder, presenting with varying combinations and severity of upper and lower motor neuron dysfunction, sensory deficits, dementia, and urinary incontinence. Onset is in the 40s or 50s. The diagnosis is made by finding polyglucosan bodies (PB) in histologic sections of brain or spinal cord, peripheral nerve, or dermal sweat glands. Although 2 pairs of the 22 previously reported cases were siblings, the familial nature of the disease has not been emphasized.

METHODS

We report 2 adult siblings, a male and a female, each of whom had the clinical diagnosis of vascular dementia. Both were confirmed at autopsy to have APBD. We characterized the lesions in autopsy tissues using a battery of histological stains, lectin histochemistry, and electron microscopy.

RESULTS

Innumerable PB were distributed throughout brain, heart, skeletal muscle, liver, and dermal sweat glands. PB were highlighted by periodic acid Schiff stain and concanavalin A lectin. Ultrastructurally, PB were composed of aggregates of filaments within axons and astrocytic processes, and lying free in the neuropil, but not within neuronal perikarya.

CONCLUSIONS

It is important to consider APBD in cases of familial dementia of unknown etiology. Ante-mortem biopsy of axillary skin may be diagnostic.

What depressive symptoms are reported in Alzheimer's patients?

PURPOSE

To ascertain the nature of depression-related symptoms in AD.

METHOD

The Hamilton Rating Scale for Depression (HAM-D) was administered as a semi-structured interview to 30 consecutive Alzheimer's disease (AD) patients who also underwent independent psychiatric evaluation. The HAM-D was also administered with a caregiver as the informant.

RESULTS

There was no relationship between the number of symptoms reported by patients or caregivers and patients' level of cognitive impairment. Symptom reports by caregivers living in the same household did not differ significantly from symptom reports by caregivers living elsewhere. Caregivers rated AD patients as having significantly more depressive symptoms than did patients themselves. The items most frequently endorsed by caregivers were psychic anxiety (77%), suspiciousness (50%), low energy (50%) and depression (43%). The items most frequently endorsed by AD patients were weight loss (36%), psychic anxiety (33%) and somatic anxiety (33%). Depression was endorsed by 20% of patients. Caregiver-respondent HAM-D scores suggested clinically significant depression in 27% of cases, but AD patients' scores suggested clinically significant depression in only 7% of cases. No case of major depression was found on psychiatric examination.

CONCLUSIONS

Depressive symptoms seemed more an executive function loss than of primary mood disturbance in that guilt, suicidal rumination and self-perceived loss of interest were uncommon, suggesting that simple environmental measures might be the most appropriate treatment of these symptoms.

Brain blood flow in the dementias: SPECT with histopathologic correlation in 54 patients

PURPOSE

To evaluate single photon emission computed tomographic (SPECT) imaging of regional cerebral blood flow in the diagnosis of Alzheimer disease (AD) and the differential diagnosis of the dementias.

MATERIALS AND METHODS

Regional cerebral blood flow SPECT was performed with inhaled xenon-133 in 261 patients and with injected technetium-99m hexamethyl-propyleneamine oxime (HMPAO) in 162 patients with possible dementia. In 16 patients, both agents were used in 1 day. SPECT images obtained in elderly healthy control subjects (with Xe-133 in 15, with Tc-99m HMPAO in 14) were available. In each patient without AD, further classification of disease was attempted. Histopathologic correlation was available in 54 patients (with autopsy in 51, with biopsy in three).

RESULTS

SPECT diagnoses were true-positive in 37, true-negative in eight, false-positive in three, and false-negative in six patients. Sensitivity was 86% (37 of 43; 95% confidence limits = .72, .95); specificity, 73% (eight of 11; confidence limits = .39, .94); positive predictive value, 92% (37 of 40; confidence limits = .80, .98); and negative predictive value, 57% (eight of 14; confidence limits = .29, .82).

CONCLUSION

Regional cerebral blood flow SPECT may assist in the early and late diagnoses of AD and in the differential-diagnosis of the dementias when there is a complicated or confusing clinical picture.

Alzheimer's disease: diagnosis and treatment

This review describes and evaluates developments in the early diagnosis and the treatment of Alzheimer's disease. It is hoped that early diagnosis of the disorder will enable treatment that will reduce or arrest the associated cognitive loss so that affected individuals can retain significant function and institutionalization can be delayed or averted. Diagnostic techniques, including use of neuropsychological measures, functional imaging measures, and biological markers, are reviewed; such techniques are useful for confirming diagnosis but do not replace a comprehensive clinical evaluation. Potential treatment modalities, such as techniques to enhance neurotransmission, replace estrogen effects, reduce the effects of free radicals, and combat inflammation, are explored. Cholinesterase inhibitors are the only modality thus far shown in large-scale studies to be effective, but their effect is small.

Altered amyloid protein processing in platelets of patients with Alzheimer disease

BACKGROUND

beta-Amyloid peptide, the core component of neuritic plaques in brain areas in patients with Alzheimer disease (AD), is 1 cleavage product of the beta-amyloid precursor protein (APP) in neurons and platelets. Alternate cleavage products of intact 140- to 150-kd APPs in platelets include nonamyloidogenic 120- to 130-kd and 110-kd isoforms. The possible differential significance of these 2 isoforms, structurally similar to protease nexin II, is unknown.

OBJECTIVE

To determine whether the ratio of the 120- to 130-kd APP isoform to the 110-kd APP isoform as processed in platelets correlates with the presence of AD and/or the apolipoprotein E4 (ApoE4) allele, which is a major risk factor for AD.

SETTING

The Alzheimer Disease Center at The University of Texas Southwestern Medical Center at Dallas.

METHODS

The APP isoforms were quantitated with the use of 2 different Western blot detection methods in platelets from 15 patients with AD and 19 control subjects in whom genotyping of apolipoprotein E was performed.

RESULTS

The mean ratio of the 120- to 130-kd APP isoform to the 110-kd APP isoform in the patients with AD was significantly lower than that of the control subjects (5.98 vs 7.64; P = .03 [method 1] and 5.98 vs 7.92; P = .01 [method 2]) after adjusting for age and the increased incidence of ApoE4 in patients with AD. The lower APP ratios were also associated with increased age and with the presence of an ApoE4 allele.

CONCLUSIONS

The APP processing in platelets of patients with AD is different from that of control subjects. This difference, largely caused by factors other than the ApoE4 genotype, may reflect chronic platelet activation in patients with AD. The use of these data to estimate "AD risk," by using the APP isoform ratio, indicates an odds ratio of 1.75, suggesting possible utility as an adjunct in the diagnosis of AD. Moreover, these findings may relate to analogous alterations in APP processing that may occur in brain areas affected by AD.

Assessment of behavioral symptoms in community-dwelling dementia patients

The authors compared the CERAD Behavior Rating Scale for Dementia (CBRSD) with the Cohen-Mansfield Agitation Inventory (CMAI) for their ability to detect behavioral symptoms in community-dwelling dementia patients with mild-to-moderate global impairment. Both instruments were administered to caregivers of 33 cognitively impaired patients seen in a dementia clinic at initial evaluation or follow-up visit. Endorsement of a higher percentage of items on the CBRSD than the CMAI suggests greater sensitivity of this instrument to the behavioral symptoms seen in community-dwelling patients. There was good correlation between the number of items endorsed on both scales but not between subscales of the CMAI and factors of the CBRSD that appeared related to agitation. Thus, the CBRSD and CMAI both seem to measure behaviors that occur in dementia patients, but the CBRSD's two agitation-related factors do not appear to measure agitation as defined by the CMAI.

Premorbid intelligence estimation and level of dementia in Alzheimer's disease

Simple sight-word reading tasks have demonstrated utility in the estimation of premorbid intelligence, although the effects of progressive dementia on such tasks has not been thoroughly examined. The present investigation sought to examine estimated IQ scores from the National Adult Reading Test-Revised (NART-R; Blair & Spreen, 1989) in relation to a WAIS-R-based (Wechsler, 1981) estimate of IQ in a series of patients with probable Alzheimer's disease across varying levels of dementia. Results suggest that while NART-R scores do show a decrement with dementia severity, this decline is mild, in contrast to traditionally based IQ scores and other measures of cognitive function, which show more marked declines. Similarly, compared with other tasks, the NART-R showed the strongest correlation with education across the sample as a whole, while the other indices were more related to level of dementia. These findings support the use of measures such as the NART-R in estimating premorbid intellectual functioning in patients at various levels of dementia severity, including those with more advanced cognitive deterioration.

Alzheimer's disease and its Lewy body variant: a clinical analysis of postmortem verified cases

OBJECTIVE

The authors compared clinical findings of Alzheimer's disease and the so-called Lewy body variant of Alzheimer's disease.

METHOD

Available data were analyzed on the clinical features of 58 patients with Alzheimer's disease and 24 patients with the Lewy body variant of Alzheimer's disease who underwent postmortem examination.

RESULTS

The proportion of men was significantly larger in the Lewy body variant group than in the Alzheimer's disease group (66.7% versus 34.5%), and, concordantly, the Lewy body variant group was slightly taller. The prevalence of hallucinations and delusions was significantly higher in Lewy body variant subjects than the Alzheimer's disease subjects, but there were no significant differences between the two groups in educational attainment, family history of dementia, age at onset, duration of illness, cognitive impairment, overall severity of illness, or neuropsychological findings. Patients with the Lewy body variant of Alzheimer's disease tended to experience more frequent extrapyramidal side effects of neuroleptics than did the patients with Alzheimer's disease, but for patients in the two groups who were not exposed to neuroleptics, there was little difference in frequency of extrapyramidal side effects. CSF concentration of homovanillic acid (HVA) was significantly lower in the Lewy body variant patients, even when correction was made for height.

CONCLUSIONS

The Lewy body variant of Alzheimer's disease may be suspected in elderly male dementia patients who otherwise meet criteria for Alzheimer's disease but who manifest significant psychiatric symptoms and neuroleptic-induced extrapy-ramidal side effects and have low levels of CSF HVA.

Genetic factors for the development of Alzheimer disease in the Cherokee Indian

OBJECTIVE

To study the relationship between the genetic degree of Cherokee ancestry, the apolipoprotein E *E4 (APOE*E4) allele type, and the development of Alzheimer disease (AD) in individuals from the Cherokee Nation who reside in northeastern Oklahoma.

SETTING

Alzheimer disease center satellite clinic and university departments of neurology, psychiatry, and academic computing.

DESIGN

Standardized dementia evaluations based on criteria from the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association were performed on 26 patients aged 65 years or older to establish a diagnosis of AD. Twenty-six control subjects were recruited and similarly assessed. The APOE allele type determinations were obtained on all patients and control subjects. Appropriate statistical analyses were used to compare the genetic degree of Cherokee ancestry, the APOE allele type, and the development of AD.

RESULTS

The data indicated that as the genetic degree of Cherokee Indian ancestry increased, the representation of AD decreased. The 9 patients with AD with a greater than 50% genetic degree of Cherokee ancestry constituted 35% of the group with AD. The 17 remaining patients with AD who were less than 50% Cherokee constituted 65% of the group with AD. In contrast, 17 (65%) of the control subjects were more than 50% Cherokee; only 9 (35%) were less than 50% Cherokee. These percentages of AD were not changed by the *E4 allele. This inverse relationship between the genetic degree of Cherokee ancestry and AD, independent of the APOE*E4 allele status, diminished with increasing age, suggesting an age-related protective effect of being Cherokee. For a decrease of 10% in Cherokee ancestry, the odds of developing AD are estimated to be 9.00 times greater at age 65 years but only 1.34 times greater at age 80 years.

CONCLUSIONS

A greater genetic degree of Cherokee ancestry reduces the risk of developing AD and, thus, seems protective. This protective genetic factor is independent of APOE allele type and diminishes with age.

The Behavior Rating Scale for Dementia of the Consortium to Establish a Registry for Alzheimer's Disease. The Behavioral Pathology Committee of the Consortium to Establish a Registry for Alzheimer's Disease

OBJECTIVE

The purpose of the study was to develop a standardized instrument, the Behavior Rating Scale for Dementia, for rating psychopathology in patients with probable Alzheimer's disease and to conduct a multicenter pilot study of this instrument.

METHOD

The rating scale was developed collaboratively on the basis of clinical experience and existing instruments. Items were scaled according to frequency of psychopathology and were administered to an informant who was familiar with the subject. The scale was administered in a standardized manner by trained examiners who had met predetermined certification standards. The study group consisted of 303 subjects with probable Alzheimer's disease who had undergone standardized clinical evaluations by the Consortium to Establish a Registry for Alzheimer's Disease.

RESULTS

Subjects had an average of 15 problems rated as present in the preceding month. Wide variability in the nature of disturbances was found, with a number of items rated as present since the illness began but not in the past month. Interrater agreement was high. Factor analysis suggested eight preliminary factors that mapped onto clinically relevant domains: depressive features, psychotic features, defective self-regulation, irritability/agitation, vegetative features, apathy, aggression, and affective lability.

CONCLUSIONS

The Behavior Rating Scale for Dementia provides a standardized, reliable measure that can be administered to caregivers of demented subjects. On the basis of the present study, the scale has been revised slightly. After additional studies in progress, the Behavior Rating Scale for Dementia will be available for general use in assessing a wide range of psychopathology in dementia.

Prevalence and incidence of major depression in Alzheimer's disease

OBJECTIVE

This study examined the prevalence and incidence of major depressive disorder in Alzheimer's disease.

METHOD

The authors retrospectively reviewed two large Alzheimer's disease databases, one at the University of Texas Southwestern Medical Center in Dallas and the other at the Consortium to Establish a Registry for Alzheimer's Disease (CERAD). The Dallas series contained 264 cases of Alzheimer's disease, of which 153 patients were followed up for an average of 3 years from initial evaluation. The CERAD database contained 1,095 cases and excluded patients with histories of depression at initial evaluation; 325 of these patients were followed up for at least 2 years. Alzheimer's disease was diagnosed according to the criteria of the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association; major depression was diagnosed according to the DSM-III-R criteria. Most of the patients in these series were dwelling in the community and had had Alzheimer's disease symptoms for approximately 4 years at the time of evaluation.

RESULTS

In the Dallas series there was a 1.5% prevalence and a 0% incidence of major depression. In the CERAD series there was a 1.3% 2-year incidence of major depression.

CONCLUSIONS

The low prevalence and incidence of DSM-III-R major depression in these patients suggest that for the period of time the patients were followed up, Alzheimer's disease did not predispose to major depression. However, major depression may herald the subsequent onset of dementia. Depression in dementia should perhaps be diagnosed by different criteria.

Cortisol secretion and Alzheimer's disease progression: a preliminary report

We report preliminary findings in a study of the relationship of plasma cortisol concentration (CORT) to the clinical progression of Alzheimer's disease (AD), testing the hypotheses that CORT predicts AD progression and that CORT increases as the disease advances. In 12 subjects with NINCDS/ADRDA probable AD, we performed cognitive testing and plasma cortisol determinations at baseline and again in 12 months. A modified Alzheimer's Disease Assessment Scale-Cognitive (ADAS-COG) measured disease progression. Plasma cortisol concentration CORT was determined at 12 AM and 1 PM, and an Afternoon Cortisol Test (ACT) was used to estimate average 24-hr CORT. Baseline 12 AM CORT correlated with the change in ADAS-COG from start of study to 12 months. No cortisol measure increased over the study period; estimated average 24-hr CORT and 12 AM CORT remained constant, whereas while 1 PM CORT declined. There was no relationship between age or duration of illness and any of the cortisol measures at baseline.

Brain blood flow in the dementias: SPECT with histopathologic correlation

Single photon emission computed tomography (SPECT) of regional cerebral blood flow (RCBF) has been employed experimentally in the assessment of patients with dementia. The standard with which the SPECT diagnosis has been compared previously has been the initial clinical diagnosis. Recognizing that histopathologic diagnosis would be a more reliable standard, the authors compared SPECT diagnoses and clinical diagnoses with histopathologic diagnoses in a series of 18 patients who had been referred by the Alzheimer Disease Research Center. SPECT RCBF studies were carried out prospectively in 15 patients with an inhaled xenon-133 SPECT technique and in three patients with technetium-99m hexamethyl-propylene-amine oxime and triple-camera-scanner SPECT. When compared with histopathologic diagnosis, clinical diagnosis was correct in 15 of 18 patients; visual scanning diagnosis, in 13 of 18; and Xe-133-SPECT diagnosis based on quantitative ratios in regions of interest, in 14 of 15 (13 of 13 with Alzheimer disease).

Xenon-133 SPECT-determined regional cerebral blood flow in Alzheimer's disease: what is typical?

A study of 76 consecutive xenon-133 SPECT studies of regional cerebral blood flow was undertaken to determine the frequency of various patterns of blood flow in cases of clinically diagnosed probable and possible Alzheimer's disease. The reference tomographic section was a slice 6 cm above and parallel to the canthomeatal line. With the use of this technique, the "classic" finding of bilateral temporoparietal (TP) flow reductions as the sole abnormality occurred in only 28% of cases. Bilateral TP reductions accompanied by bilateral or unilateral frontal flow reductions were nearly as common (24%), and other patterns accounted for the other 48% of cases.