Cognitive models of medical decision-making capacity in patients with mild cognitive impairment.

This study investigated cognitive predictors of medical decision-making capacity (MDC) in patients with amnestic mild cognitive impairment (MCI). A total of 56 healthy controls, 60 patients with MCI, and 31 patients with mild Alzheimer's disease (AD) were administered the Capacity to Consent to Treatment Instrument (CCTI) and a neuropsychological test battery. The CCTI assesses MDC across four established treatment consent standards--S1 (expressing choice), S3 (appreciation), S4 (reasoning), and S5 (understanding)--and one experimental standard [S2] (reasonable choice). Scores on neuropsychological measures were correlated with scores on each CCTI standard. Significant bivariate correlates were subsequently entered into stepwise regression analyses to identity group-specific multivariable predictors of MDC across CCTI standards. Different multivariable cognitive models emerged across groups and consent standards. For the MCI group, measures of short-term verbal memory were key predictors of MDC for each of the three clinically relevant standards (S3, S4, and S5). Secondary predictors were measures of executive function. In contrast, in the mild AD group, measures tapping executive function and processing speed were primary predictors of S3, S4, and S5. MDC in patients with MCI is supported primarily by short-term verbal memory. The findings demonstrate the impact of amnestic deficits on MDC in patients with MCI.

A polymorphism in SOD2 is associated with development of Alzheimer's disease.

Genes involved in cellular mechanisms to repair oxidative damage are strong candidates as etiologic factors for Alzheimer's disease (AD). One important enzyme involved in this mechanism is superoxide dismutase 2 (SOD2). The gene for this enzyme lies within a single haplotype block at 6q25.3, a region showing evidence for linkage to AD in a genome scan. We genotyped four single nucleotide polymorphisms (SNPs) in SOD2 in families of the National Institute of Mental Health-AD Genetics Initiative (ADGI): rs2758346 in the 5' untranslated region (UTR), rs4880 in exon 2, rs2855116 in intron 3 and rs5746136 in the 3'UTR. Under a dominant model, family-based association tests showed significant evidence for association of AD with the first three loci in a candidate gene set of families with individuals having age of onset of at least 50 years and two affected and one unaffected sibling, and in a late-onset subset of families (families with all affected individuals having age of onset of at least 65 years) from the full ADGI sample. The alleles transmitted more frequently to cases than expected under the null hypothesis were T, C, G, and G. Global tests of the transmission of haplotypes indicate that the first two loci have the most consistent association with risk of AD. Because of the high linkage disequilibrium in this small (14 kb) gene, and the presence of 100 SNPs in this gene, 26 of which may have functional significance, additional genotyping and sequencing are needed to identify the functionally relevant SNP. We discuss the importance of our findings and the relevance of SOD2 to AD risk.

Assessing the competency of patients with Alzheimer's disease under different legal standards. A prototype instrument.

OBJECTIVE: To assess empirically the competency of patients with Alzheimer's disease (AD) to consent to medical treatment under different legal standards (LSs). DESIGN: Comparison of normal older subjects and patients with AD on measures of competency to consent to medical treatment. SETTING: University medical center. SUBJECTS: Normal older control subjects (n = 15) and patients with probable AD (n = 29 [15 with mild and 14 with moderate AD]). MAIN OUTCOME MEASURES: Two specialized clinical vignettes were developed that test a subject's capacity to consent to medical treatment under five well-established LSs for this competency: LS1, evidencing treatment choice; LS2, making the reasonable choice; LS3, appreciating consequences of choice; LS4, providing rational reasons for choice; and LS5, understanding treatment situation and choices. Performance on the LSs was compared across control and AD groups using Student's t test, chi 2, and analysis of variance. Demented subjects were categorized as competent, marginally competent, or incompetent under each LS by using a cutoff score derived from normal control performance. RESULTS: No differences between groups emerged for LS1 and LS2. Control subjects performed significantly better than patients with mild AD on LS4 and LS5, and significantly better than patients with moderate AD on LS3, LS4, and LS5. Patients with mild AD performed significantly better than patients with moderate AD on LS4 and LS5. With respect to competency status, patients with AD showed a consistent and progressive pattern of compromise (marginal competence or incompetence) related to dementia severity and stringency of the LS. CONCLUSIONS: A reliable prototype instrument validly discriminated the competency performance and classified the competency status of control subjects and patients with mild and moderate AD under five LSs for competency to consent to medical treatment. While the groups performed equivalently on minimal standards requiring merely a treatment choice (LS1) or the reasonable treatment choice (LS2), patients with mild AD had difficulty with more difficult standards requiring rational reasons (LS4) and understanding treatment information (LS5), and patients with moderate AD had difficulty with appreciation of consequences (LS3), rational reasons (LS4), and understanding treatment (LS5). The results raised the concern that many patients with mild AD may not be competent to consent to treatment and supported the value of standardized clinical vignettes for assessment of competency in dementia.

Neuropsychologic predictors of competency in Alzheimer's disease using a rational reasons legal standard.

OBJECTIVE: To identify neuropsychologic predictors of competency performance and status in Alzheimer's disease (AD) using a specific legal standard (LS). This study is a follow-up to the competency assessment research reported in this issue of the archives. DESIGN: Univariate and multivariate analyses of independent neuropsychologic test measures with a dependent measure of competency to consent to treatment. SETTING: University medical center. SUBJECTS: Fifteen normal older control subjects and 29 patients with probable AD. MAIN OUTCOME MEASURES: Subjects were administered a battery of neuropsychologic measures theoretically linked to competency function, as well as two clinical vignettes testing their capacity to consent to medical treatment under five different LSs. The present study focused on one specific LS: the capacity to provide "rational reasons" for a treatment choice (LS4). Neuropsychologic test scores were correlated with scores on LS4 for the normal control group and the AD group. The resulting univariate predictors were then analyzed using stepwise regression and discriminant function to identify the key multivariate predictors of competency performance and status under LS4. RESULTS: Measures of word fluency predicted the LS4 scores of controls (R2 = .33) and the AD group (R2 = .36). A word fluency measure also emerged as the best single predictor of competency status for the full subject sample (n = 44), correctly classifying 82% of cases. Dementia severity (Mini-Mental State Examination score) did not emerge as a multivariate predictor of competency performance or status. Interestingly, measures of verbal reasoning and memory were not strongly associated with LS4. CONCLUSIONS: Word fluency measures predicted the normative performance and intact competency status of older control subjects and the declining performance and compromised competency status of patients with AD on a "rational reasons" standard of competency to consent to treatment. Cognitive capacities related to frontal lobe function appear to underlie the capacity to formulate rational reasons for a treatment choice. Neuropsychologic studies of competency function have important theoretical and clinical value.

Reliability and validity of NINCDS-ADRDA criteria for Alzheimer's disease. The National Institute of Mental Health Genetics Initiative.

OBJECTIVE: To assess interrater reliability and validity of NINCDS-ADRDA (National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association) criteria for Alzheimer's disease (AD). DESIGN: A multisite reliability and validity study in which clinicians from each site diagnosed 60 case summaries yielding a preconsensus estimate of reliability and validity. A consensus conference was conducted for each disagreement, leading to a postconsensus estimate of validity. The criterion standard was a diagnosis of AD by autopsy. SETTING: Three academic medical centers. SUBJECTS: A convenience sample of 60 detailed case summaries, 40 with AD and 20 with other dementing disorders. MAIN OUTCOME MEASURES: The kappa coefficient, sensitivity, and specificity. RESULTS: The kappa coefficient for preconsensus agreement on a diagnosis of probable or possible AD vs non-AD was 0.51; the sensitivity of a diagnosis of probable or possible AD for a pathological diagnosis of AD was 0.81, and the specificity was 0.73. The postconsensus sensitivity was 0.83, and the specificity was 0.84. CONCLUSIONS: The results support the reliability and validity of NINCDS-ADRDA criteria and show that the consensus process may improve diagnostic accuracy. The cases are reviewed with a focus on the sources of diagnostic disagreements and errors and possible changes that might improve the accuracy of the criteria.

The relationship of high-intensity signals on magnetic resonance images to cognitive and psychiatric state in Alzheimer's disease.

In Alzheimer's disease (AD), the relationship between white-matter changes on magnetic resonance images and behavior are unclear. Therefore, magnetic resonance images, cognition, and psychiatric state were assessed in patients with AD with depression (AD/DEP; n = 18) and without depression (AD; n = 45), older depressed patients (n = 12) and older normal individuals (n = 25). High-intensity signals in the cortex and subcortical regions were similar in number and proportions among all groups, even when hypertensive patients were excluded. No correlations to cognitive or psychiatric state were found. Periventricular signals were categorized using a 1- (absent) to 6- (thick, irregular caps and stripes) point scale. The categories were similar among groups except that patients with AD exhibited more category 5 changes than did normal subjects, neuropsychological performance was significantly worse in patients with AD who had category 5 and 6 changes when compared to those in category 1. These results suggest that periventricular changes may predict poor neuropsychological performance in patients with AD. However, neither deep white-matter lesions nor periventricular changes are useful for diagnostic purposes.

Assessing financial capacity in patients with Alzheimer disease: A conceptual model and prototype instrument.

OBJECTIVE: To investigate financial capacity in patients with Alzheimer disease (AD) using a new theoretical model and prototype psychometric instrument. DESIGN: Cross-sectional comparisons of older control subjects (n=23) and patients with mild (n=30) and moderate AD (n=20). MAIN OUTCOME MEASURES: Financial capacity was measured using the Financial Capacity Instrument, a prototype psychometric instrument that tests financial capacity using 14 tasks of financial ability comprising 6 clinically relevant domains of financial activity: basic monetary skills, financial conceptual knowledge, cash transactions, checkbook management, bank statement management, and financial judgment. RESULTS: The Financial Capacity Instrument tasks and domains showed adequate to excellent internal, interrater, and test-retest reliabilities. At the task level, patients with mild AD performed equivalently with controls on simple tasks such as counting coins/currency and conducting a 1-item grocery purchase, but significantly below controls on more complex tasks such as using a checkbook/register and understanding and using a bank statement. At the domain level, patients with mild AD performed significantly below controls on all domains except basic monetary skills. Patients with moderate AD performed significantly below controls and patients with mild AD on all tasks and domains. Regarding capacity status outcomes (capable, marginally capable, incapable) on domains, patients with mild AD had high proportions of marginally capable or incapable outcomes (range, 47%-87%), particularly on difficult domains like bank statement management (domain 5) and financial judgment (domain 6), but variability in individual outcomes. Patients with moderate AD had almost exclusively incapable outcomes across the 6 domains (range, 90%-100%). CONCLUSIONS: Financial capacity is already significantly impaired in mild AD. Patients with mild AD demonstrate deficits in more complex financial abilities and impairment in most financial activities. Patients with moderate AD demonstrate severe impairment of all financial abilities and activities. The Financial Capacity Instrument has promise as an instrument for assessing domain-level financial activities and task-specific financial abilities in patients with dementia. Arch Neurol. 2000.

Magnetic resonance imaging and the diagnosis of dementia.

We describe seven patients with clinical, laboratory, and CT evidence of primary degenerative dementia (Alzheimer's, Pick's). Magnetic resonance imaging demonstrated regions in the white matter consistent with cerebral infarction. MRI may be a sensitive way to differentiate multi-infarct dementia and primary degenerative dementia.

The effect of long-term physostigmine administration in Alzheimer's disease.

We assessed the effect of chronic long-term physostigmine in 20 patients with probable Alzheimer's disease. Initially, all patients went through a dose-finding phase and a double-blind crossover period, and were subsequently classified as physostigmine responders or nonresponders based on an a priori classification system. We then offered all patients long-term treatment with physostigmine regardless of their initial classification. Results revealed that responders spent significantly (p less than 0.0005) longer time periods on drug (36.1 +/- 4.6 months) than nonresponders (10.8 +/- 3.2). During a 2nd crossover period, 18 months into treatment, responders still demonstrated behavioral improvement, as assessed with the Sandoz Clinical Assessment-Geriatric Scale, whereas there were no behavioral changes observed in nonresponders. There were no effects on formal neuropsychological assessment. The results suggest that a subgroup of Alzheimer's patients benefits from long-term physostigmine therapy.

Toward a neurologic model of competency: Cognitive predictors of capacity to consent in Alzheimer's disease using three different legal standards.

OBJECTIVE: To identify cognitive predictors of competency performance and status in Alzheimer's disease (AD) using three differentially stringent legal standards for capacity to consent. DESIGN: Univariate and multivariate analyses of independent neuropsychological test measures with three dependent measures of competency to consent to treatment. SETTING: University medical center. SUBJECTS: 15 normal older controls and 29 patients with probably AD (15 mild and 14 moderate). MAIN OUTCOME MEASURES: Subjects were administered a batter of neuropsychological measures theoretically linked to competency function, as well as two clinical vignettes testing capacity to consent to medical treatment under five legal standards (LSs). The present study focused on three differentially stringent LSs: the capacity simply to "evidence a treatment of choice" (LS1), which is a minimal standard; the capacity to "appreciate the consequences" of a treatment of choice (LS3), a moderately stringent standard; and the capacity to "understand the treatment situation and choices" (LS5), the most stringent standard. Control subject and AD patient neuropsychological test scores were correlated with scores on the three LSs. The resulting univariate correlates were than analyzed using stepwise regression and discriminant function to identify key multivariate predictors of competency performance and status under each LS. RESULTS: No neuropsychological measures predicted control group performance on the LSs. For the AD group, a measure of simple auditory comprehension predicted LS1 performance (r(2)=0.44, p < 0.0001), a word fluency measure predicted LS3 performance (r(2)=0.58, p < 0.0001), and measures of conceptualization and confrontation naming together predicted LS5 performance (r(2)=0.81, p < 0.0001). Under discriminant function analysis, confrontation naming was the best single predictor of LS1 competency status for all subjects, correctly classifying 96% of cases (42/44). Measures of visumotor tracking and confrontation naming were the best single predictors, respectively, of competency status under LS3 (91% [39/43]) and LS5 (98% [43/44]). CONCLUSIONS: Multiple cognitive functions are associated with loss of competency in AD. Deficits in conceptualization, semantic memory, and probably verbal recall are associated with the declining capacity of mild AD patients to understand a treatment situation and choices (LS5); executive dysfunction with the declining capacity of mild to moderate AD patients to identify the consequences of treatment choice (LS3); and receptive aphasia and severe dysnomia with the declining capacity of advanced AD patients to evidence a simple treatment choice (LS1). The results offer insight into the relationship between different legal thresholds of competency and the progressive cognitive changes characteristic of AD, and represent an initial step toward a neurologic model of competency.

HTLV-I-associated myelopathy and polymyositis in a US native.

A patient who had always lived in the United States had an HTLV-I infection and a chronic myelopathy clinically mimicking amyotrophic lateral sclerosis. Needle EMG and nerve conduction studies were consistent with anterior horn cell disease but muscle biopsy showed denervation and an inflammatory myopathy. Serum HTLV-I antibody tests were positive and HTLV-I DNA was present in peripheral leukocytes. This is the 1st reported US native with HTLV-I-associated myelopathy and polymyositis.

Error behaviors associated with loss of competency in Alzheimer's disease.

OBJECTIVE: To investigate qualitative behavioral changes associated with declining medical decision-making capacity (competency) in patients with AD. BACKGROUND: Qualitative measures can yield clinical information about functional changes in neurologic disease not available through quantitative measures. METHODS: Normal older controls (n = 21) and patients with mild and moderate probable AD (n = 72) were compared using a standardized competency measure and neuropsychological measures. A system of 16 qualitative error scores representing conceptual domains of language, executive dysfunction, affective dysfunction, and compensatory responses was used to analyze errors produced on the competency measure. Patterns of errors were examined across groups. Relationships between error behaviors and competency performance were determined, and neurocognitive correlates of specific error behaviors were identified. RESULTS: AD patients demonstrated more miscomprehension, factual confusion, intrusions, incoherent responses, nonresponsive answers, loss of task, and delegation than controls. Errors in the executive domain (loss of task, nonresponsive answer, and loss of detachment) were key predictors of declining competency performance by AD patients. Neuropsychological analyses in the AD group generally confirmed the conceptual domain assignments of the qualitative scores. CONCLUSIONS: Loss of task, nonresponsive answers, and loss of detachment were key behavioral changes associated with declining competency of AD patients and with neurocognitive measures of executive dysfunction. These findings support the growing linkage between executive dysfunction and competency loss.

The consortium to establish a registry for Alzheimer's Disease (CERAD). Part XIII. Obtaining autopsy in Alzheimer's disease.

Although autopsy rates in the United States have been decreasing steadily, the necessity for brain autopsy to confirm Alzheimer's disease (AD) remains. Of 308 consecutively deceased AD patients at 24 CERAD (Consortium to Establish a Registry for Alzheimer's Disease) sites, 167 (54%) were autopsied; 141 (46%) were not. The autopsied and nonautopsied groups were comparable in gender (men, 57.5% versus 49.7%), marital status (married, 69.3% versus 67.1%), age at entry (73 versus 74 years), age at death (76 versus 77 years), and stage of disease at entry (mild, 46% versus 43%). However, the autopsied patients were significantly more likely to be white (94.5% versus 82.1%), to be better educated (13.1 versus 11.3 years), to have been in the study longer (mean, 3.3 versus 2.6 years), and to have had longer total duration of AD (8.1 versus 6.7 years). Of the 24 CERAD sites, 13 stressed the importance of autopsy by dedicating a staff member to seek autopsy and by providing free autopsy and transportation; 11 did not. Logistic regression analysis showed that white race (odds ratio [OR] = 2.74; 95% confidence interval [CI] = 1.10-6.83), increased education (OR = 1.12; 95% CI = 1.04-1.21), and emphasis on autopsy (OR = 4.69; 95% CI = 2.67-8.25) were the only significant factors. Although race and education were important, autopsy was more likely to be obtained when sites dedicated resources to this endeavor.

ApoE-4 and age at onset of Alzheimer's disease: the NIMH genetics initiative.

OBJECTIVE: To explore the impact of apoE-4 on Alzheimer's disease (AD) and its age at onset. DESIGN: A genetic linkage study using affected relative pairs, predominantly siblings. SETTING: Three academic medical centers ascertained subjects from memory disorder clinics, nursing homes, and the local community. SUBJECTS: 310 families including 679 subjects with AD by NINCDS/ADRDA and/or Khachaturian criteria and 231 unaffected subjects. OUTCOME MEASURE: ApoE genotype. ANALYTIC METHODS: Association, affected pedigree member, sibling pair, and lod score analyses. RESULTS: ApoE-4 was strongly associated with AD in this sample (allele frequency = 0.46 vs. 0.14 in controls, p < 0.000001). Results of lod score, affected pedigree member analysis, and sib-pair analysis also supported apoE-4 as a risk factor for AD. When the sample was stratified on family mean age at onset, the risk conferred by apoE-4 was most marked in the 61 to 65 age group. Individuals with two copies of apoE-4 had a significantly lower age at onset than those with one or no copies (66.4 vs. 72.0, p < 0.001), but individuals with one copy did not differ from those with none. Within families, the individual with the earliest age at onset had, on average, significantly more apoE-4 alleles (p < 0.0001) than the individual with the latest onset. DISCUSSION: This work supports previous reports of an association between apoE-4 and the development of AD and demonstrates that apoE-4 exerts its maximal effect before age 70. These findings have important implications for the potential use of apoE genotyping for diagnosis and prediction of disease. They also underscore the need to identify additional genetic factors involved in AD with onset beyond age 70 years.

Cholinergic influences on hippocampal glucose metabolism.

2-Deoxy-D-[3H]glucose autoradiography was employed to investigate the effects of acute cholinergic manipulations on hippocampal glucose metabolism. In general, manipulations designed to reduce cholinergic activity (medial septal ablation, atropine treatment) reduced hippocampal glucose metabolism. Maximal decrements were found in the terminal fields of the septohippocampal projection after medial septal lesions, while maximal deficits after atropine treatment correlated with muscarinic receptor binding. Electrical stimulation of the medial septum resulted in increased glucose utilization in some terminal fields of the septohippocampal projection and decreased utilization in the terminal fields of the perforant pathway. Our data clearly indicate that acute alterations in cholinergic activity can affect hippocampal glucose metabolism but the distribution, direction and degree of these changes is dependent on the specific treatment.

Apoptotic protein expression and activation of caspases is changed following cholinergic denervation and hippocampal sympathetic ingrowth in rat hippocampus.

Following cholinergic denervation of the hippocampus by medial septal lesions, an unusual neuronal reorganization occurs in which peripheral adrenergic fibers arising from superior cervical ganglia grow into the hippocampus (hippocampal sympathetic ingrowth). Recent studies suggest that a similar process, in which sympathetic noradrenergic axons invade the hippocampus, can occur in Alzheimer's disease patients. In the last few years, the occurrence of apoptotic cell death has been studied in Alzheimer's disease patients and in animal models of this disorder. Several studies suggest that the hippocampus is an important area to be considered for apoptotic cell death. In our studies in the rat hippocampus, we have measured the expression of inducers and blockers of apoptosis in membrane, cytosolic and mitochondrial fractions, and the activity of caspases. The level of cytosolic Fas was increased in cholinergic denervation compared to control and hippocampal sympathetic ingrowth groups. The membrane Fas ligand expression was significantly increased in hippocampal sympathetic ingrowth and in cholinergic denervation compared to the control group. The level of caspase-3 (CPP32) was increased in the cholinergic denervation group compared to control and hippocampal sympathetic ingrowth groups. The cytosolic expression of bcl-x was increased in hippocampal sympathetic ingrowth compared to control and cholinergic denervation. The cytosolic activity of caspase-3 appeared to be significantly decreased in hippocampal sympathetic ingrowth and increased in cholinergic denervation groups compared to control and cholinergic denervation/hippocampal sympathetic ingrowth, respectively. From the present results, we suggest that cholinergic denervation may be responsible for pro-apoptotic responses, while hippocampal sympathetic ingrowth may protect neurons from apoptosis in rat dorsal hippocampus.

Effect of hippocampal sympathetic ingrowth and cholinergic denervation on hippocampal phospholipase C activity and G-protein function.

Following cholinergic denervation of the hippocampal formation, via medial septal lesions, peripheral noradrenergic fibers, originating from the superior cervical ganglion, grow into the hippocampus. In previous studies, we have found that hippocampal sympathetic ingrowth and cholinergic denervation alone (animals with concurrent medial septal lesions and superior cervical ganglionectomy) alter phosphoinositide turnover and muscarinic cholinergic receptors in such a way as to suggest an alteration in coupling between the muscarinic cholinergic receptors and phosphoinositol turnover. To test this hypothesis we examined the effect of hippocampal sympathetic ingrowth and cholinergic denervation on phospholipase C activity, G-protein function and the whole receptor complex by measuring the amount of phosphoinositide hydrolysed in hippocampal membranes of the rat. Neither hippocampal sympathetic ingrowth nor cholinergic denervation was found to alter phospholipase C activity when activated by increasing concentrations of Ca2+. In dorsal hippocampus, cholinergic denervation, when compared to hippocampal sympathetic ingrowth and controls, was found to decrease the amount of phosphoinositol hydrolysed when stimulated with the GTP analog, guanosine-5'-O-(3-thiotriphosphate). When guanosine-5'-O-(3-thiotriphosphate) plus carbachol (1 mM) was utilized to stimulate the entire receptor complex, phosphoinositol hydrolysis was found to be decreased in the cholinergic denervation group as compared to both hippocampal sympathetic ingrowth and control groups. This effect was maximum at 3 microM guanosine-5'-O-(3-thiotriphosphate). These results suggest that both hippocampal sympathetic ingrowth and cholinergic denervation affect the efficiency of coupling between the muscarinic cholinergic receptors and phosphoinositol turnover, with cholinergic denervation decreasing and hippocampal sympathetic ingrowth "normalizing" efficiency. Further, they suggest that the G-protein is the site at which hippocampal sympathetic ingrowth and cholinergic denervation mediate their effects. The results of these experiments are also discussed within the context of recent findings demonstrating G-protein abnormalities in Alzheimer's disease.

Effect of phospholipase C and protein kinase C following cholinergic denervation and hippocampal sympathetic ingrowth in rat hippocampus.

Following cholinergic denervation of the hippocampus by medial septal lesions, an unusual neuronal reorganization occurs in which peripheral adrenergic fibers arising from the superior cervical ganglia grow into the hippocampus (hippocampal sympathetic ingrowth). We have reported previously that cholinergic denervation and hippocampal sympathetic ingrowth differentially affected cholinergically stimulated phosphoinositide hydrolysis, concentration and affinity of muscarinic receptors, Go-protein level and protein kinase C activity. To complete these studies, we determined whether cholinergic denervation and hippocampal sympathetic ingrowth influenced phospholipase C and protein kinase C expression in dorsal hippocampal membranes and cytosol. Using immunoblotting methods, the results showed that the 100,000 mol. wt subunit of phospholipase Cbeta was increased in the membrane fraction in the hippocampal sympathetic ingrowth group by 45% compared to controls and the 150,000 mol.wt subunit was increased by 75% and 59% compared to controls and cholinergic denervation, respectively. For protein kinase C detection, immunoblots were prepared using antibodies selective for "classical" protein kinase C members (alpha, beta, gamma) and for the "novel" protein kinase C subfamily members (delta, θ). Membrane protein kinase Cbeta was decreased in hippocampal sympathetic ingrowth by 35% compared to controls and by 41% compared to cytosolic hippocampal sympathetic ingrowth. Membrane protein kinase Cbeta was decreased in cholinergic denervation by 28% compared to controls. When compared to membranes from controls and the cholinergic denervation group, and to cytosolic fractions from the hippocampal sympathetic ingrowth groups, respectively, the following membrane protein kinase isoforms were found to be decreased by hippocampal sympathetic ingrowth: gamma by 55%, 40% and 57%; delta by 91.5%, 70% and 120%; theta; by 95%, 100% and 86%.In conclusion, our results may indicate the connection between the previously reported differential influence of hippocampal sympathetic ingrowth and cholinergic denervation on cholinergically stimulated phosphoinositol hydrolysis. The "normalization" of phosphoinositol hydrolysis found in hippocampal sympathetic ingrowth may be due to the increase in phospholipase Cbeta expression in hippocampal sympathetic ingrowth membrane fractions. Since the activation of protein kinase C is known to block phosphoinositol hydrolysis, hippocampal sympathetic ingrowth "normalization" of phosphoinositol hydrolysis may result from a reduction in protein kinase expression in hippocampal sympathetic ingrowth membranes.

Cholinergic denervation and sympathetic ingrowth result in persistent changes in hippocampal muscarinic receptors.

Our laboratory has been utilizing the model of hippocampal sympathetic ingrowth, which has been suggested to occur in Alzheimer's disease, to investigate the effects of cholinergic denervation and hippocampal rearrangements. After cholinergic denervation by medial septal lesions, peripheral sympathetic fibres originating from the superior cervical ganglia grow into the rat hippocampus. This hippocampal sympathetic ingrowth can be prevented by superior cervical ganglionectomy. We examined the long-term effects of these treatments on muscarinic receptors by comparing [3H]quinuclidinyl benzilate binding in rat dorsal hippocampus four and 12 weeks post lesion. Four groups of animals were employed, including controls (sham lesion+sham ganglionectomy), animals with ingrowth (medial septal lesion+ sham ganglionectomy), animals with cholinergic denervation alone (medial septal lesion+ ganglionectomy), and ganglionectomy alone (sham lesion+ganglionectomy) animals. In dorsal hippocampus four weeks post lesion, binding affinity was similar among all groups, while muscarinic receptor number was increased in ingrowth animals as compared to both the control (P<0.0002) and ganglionectomy animals (P<0.01). By 12 weeks, receptor affinity was significantly decreased in ingrowth (P<0.0001) and cholinergic denervation (P<0.0003) groups, and receptor number remained significantly elevated in ingrowth animals as compared to control (P<0.01), ganglionectomy (P<0.02) and cholinergic denervation (P<0.01) groups. The decrease in muscarinic receptor affinity may provide some insight into the ineffectiveness of cholinomimetic therapies in Alzheimer's disease, in that agonist efficacy would be reduced at the receptor.

Regional stability of cerebral blood flow measured by repeated technetium-99m-HMPAO SPECT: implications for the study of state-dependent change.

UNLABELLED: The replicability of resting state rCBF has implications for the analysis of cerebral activation protocols and the interpretation of rCBF in disease states. This study examined the stability of rCBF as measured by two resting state 99mTc-HMPAO brain SPECT scans with an emphasis on examining the contribution of specific cerebral regions to within and between subjects variance. METHODS: Nine normal, medically healthy subjects underwent two 99mTc-HMPAO brain SPECT scans under identical conditions separated by 48 hr. A reference system and semiautomated computer ROI method was used to enable accurate alignment and cortical analysis of the two scans. RESULTS: Mean within-subject difference between Scans 1 and 2 was 2.8% (range 0%-7.8%) for the 36 cortical ROIs. The mean between-subject coefficient of variation was 10% (range 7%-15%) for these ROIs. Correlation analysis of rCBF pattern replication for all slice levels yielded a highly significant overall consistency of pattern within subjects (Pearson r = 0.698, p = 0.0001). Variance component analysis revealed regional heterogeneity in between-subjects variance, with significantly greater variability found in frontal regions. The within-subject repeated measures variability was not significantly different across regions. CONCLUSION: Good within-subject 48-hr replicability indicates that individual resting state rCBF reflects fairly stable, subject-specific factors. This also justifies comparing state-dependent studies separated by a modest length of time. Although individual patterns of rCBF replicate well, the larger contribution of frontal regions to normal between-subjects variance makes evaluating the frontal effects of disease or activation more difficult.