Psychotic Alzheimer's disease is associated with gender-specific tau phosphorylation abnormalities

Converging evidence suggests that psychotic Alzheimer's disease (AD + P) is associated with an acceleration of frontal degeneration, with tau pathology playing a primary role. Previous histopathologic and biomarker studies have specifically implicated tau pathology in this condition. To precisely quantify tau abnormalities in the frontal cortex in AD + P, we used a sensitive biochemical assay of total tau and 4 epitopes of phospho-tau relevant in AD pathology in a postmortem sample of AD + P and AD - P. Samples of superior frontal gyrus from 26 AD subjects without psychosis and 45 AD + P subjects with psychosis were analyzed. Results of enzyme-linked immunosorbent assay demonstrate that AD + P females, but not males, had significantly higher levels of phosphorylated tau in the frontal cortex. In males, but not females, AD + P was associated with the presence of α-synuclein pathology. These results support a gender dissociation of pathology in AD + P. The design of future studies aimed at the elucidation of cognitive and/or functional outcomes; regional brain metabolic deficits; or genetic correlates of AD + P should take gender into consideration.

Pathogenic tau species drive a psychosis-like phenotype in a mouse model of Alzheimer's disease

Psychotic Alzheimer's disease (AD+P) is a rapidly progressive variant of AD associated with an increased burden of frontal tau pathology that affects up to 50% of those with AD, and is observed more commonly in females. To date, there are no safe and effective medication interventions with an indication for treatment in this condition, and there has been only very limited exploration of potential animal models for pre-clinical drug development. Pathogenic tau is over represented in the frontal cortex in AD+P, especially in females. In order to develop a candidate animal model of AD+P, we employed a tau mouse model with a heavy burden of frontal tau pathology, the rTg(tauP301L)4510 mouse, hereafter termed rTg4510. We explored deficits of prepulse inhibition of acoustic startle (PPI), a model of psychosis in rodents, and the correlation between pathogenic phospho-tau species associated with AD+P and PPI deficits in female mice. We found that female rTg4510 mice exhibit increasing PPI deficits relative to littermate controls from 4.5 to 5.5 months of age, and that these deficits are driven by insoluble fractions of the phospho-tau species pSer396/404, pSer202, and pThr231 found to be associated with human AD+P. This preliminary data suggests the utility of the rTg4510 mouse as a candidate disease model of human female AD+P. Further work expanded to include both genders and other behavioral outcome measures relevant to AD+P is necessary.

Psychosis in Alzheimer's disease is associated with frontal metabolic impairment and accelerated decline in working memory: findings from the Alzheimer's Disease Neuroimaging Initiative

OBJECTIVE

An ascendant body of evidence suggests that Alzheimer disease with psychosis (AD+P) is a distinct variant of illness with its own genetic diathesis and a unique clinical course. Impaired frontal lobe function has been previously implicated in AD+P. The current exploratory study, presented in two parts, evaluates both the regional brain metabolic and psychometric correlates of psychosis in a longitudinal sample of subjects with AD, made available by the Alzheimer's Disease Neuroimaging Initiative (ADNI).

METHODS

In Part 1 of the study, 21 ADNI participants with AD who developed psychotic symptoms during the study but were not psychotic at baseline were matched with 21 participants with AD who never became psychotic during the study period, and mean brain [F(18)]fluorodeoxyglucose positron emission tomography (FDG-PET) Cerebral metabolic rate for glucose (CMRgl) by regions of interest (ROIs) were compared Additionally, 39 participants with active psychosis at the time of image acquisition were matched with 39 participants who were never psychotic during the study period, and mean brain FDG-PET CMRgl by sROI were compared. In Part 2 of the study, 354 ADNI participants with AD who were followed for 24 months with serial psychometric testing were identified, and cognitive performance and decline were evaluated for correlation with psychotic symptoms.

RESULTS

Part 1: There were no regional brain metabolic differences between those with AD destined to become psychotic and those who did not become psychotic. There was a significant reduction in mean orbitofrontal brain metabolism in those with active psychosis. Part 2: Over the course of study follow-up, psychosis was associated with accelerated decline in functional performance as measured by the Functional Assessment Questionnaire, the Mini-Mental State Examination, and Forward Digit Span.

CONCLUSION

In a sample drawn from the ADNI dataset, our exploratory FDG-PET findings and longitudinal cognitive outcomes support the hypofrontality model of AD+P. Focal frontal vulnerability may mediate the accelerated decline seen in AD+P.

Optimal treatment of Alzheimer's disease psychosis: challenges and solutions

Psychotic symptoms emerging in the context of neurodegeneration as a consequence of Alzheimer's disease was recognized and documented by Alois Alzheimer himself in his description of the first reported case of the disease. Over a quarter of a century ago, in the context of attempting to develop prognostic markers of disease progression, psychosis was identified as an independent predictor of a more-rapid cognitive decline. This finding has been subsequently well replicated, rendering psychotic symptoms an important area of exploration in clinical history taking - above and beyond treatment necessity - as their presence has prognostic significance. Further, there is now a rapidly accreting body of research that suggests that psychosis in Alzheimer's disease (AD+P) is a heritable disease subtype that enjoys neuropathological specificity and localization. There is now hope that the elucidation of the neurobiology of the syndrome will pave the way to translational research eventuating in new treatments. To date, however, the primary treatments employed in alleviating the suffering caused by AD+P are the atypical antipsychotics. These agents are approved by the US Food and Drug Administration for the treatment of schizophrenia, but they have only marginal efficacy in treating AD+P and are associated with troubling levels of morbidity and mortality. For clinical approaches to AD+P to be optimized, this syndrome must be disentangled from other primary psychotic disorders, and recent scientific advances must be translated into disease-specific therapeutic interventions. Here we provide a review of atypical antipsychotic efficacy in AD+P, followed by an overview of critical neurobiological observations that point towards a frontal, tau-mediated model of disease, and we suggest a new preclinical animal model for future translational research.

Medical outcome of patients with dementia in a free-standing psychiatric hospital

BACKGROUND

The hospital outcome of patients with dementia is significantly worse than that of cognitively intact persons of the same age admitted to medical or surgical units but has not been investigated in psychiatric settings.

AIM OF STUDY

To determine the medical outcome of patients with dementia admitted for behavioral disturbance to a free-standing psychiatric hospital.

METHODS

Emergency transfers from the psychiatric setting to a general hospital were used as proxies for medical deteriorations occurring among the 71 patients with dementia (age 78.4 ± 10.4 years; 40.1% males) and 71 age- and gender-matched nondementia control patients. The patients were identified in a cohort of 1000 patients consecutively admitted to a free-standing mental health institution. Logistic regression was used to determine the clinical and laboratory variables independently associated with medical deteriorations.

RESULTS

A total of 30 patients with dementia and 25 nondementia patients were transferred to a general hospital after an acute medical deterioration (42.3% vs 35.2%, P = .38). Febrile illnesses and falls with head trauma were the most common reasons for transfers in the dementia group, in which they constituted more than half of medical deteriorations, a proportion significantly higher than in the control group (P = .011). Admission hemoglobin levels were the only independent predictor of medical deterioration in this geriatric sample.

CONCLUSIONS

Although nearly 50% of patients with dementia admitted for behavioral disturbance to a free-standing psychiatric institution required transfer to a general hospital, their rate of medical deteriorations was similar to age-matched nondementia control patients.

CALHM1 P86L polymorphism modulates CSF Aβ levels in cognitively healthy individuals at risk for Alzheimer's disease

The calcium homeostasis modulator 1 (CALHM1) gene codes for a novel cerebral calcium channel controlling intracellular calcium homeostasis and amyloid-β (Aβ) peptide metabolism, a key event in the etiology of Alzheimer's disease (AD). The P86L polymorphism in CALHM1 (rs2986017) initially was proposed to impair CALHM1 functionally and to lead to an increase in Aβ accumulation in vitro in cell lines. Recently, it was reported that CALHM1 P86L also may influence Aβ metabolism in vivo by increasing Aβ levels in human cerebrospinal fluid (CSF). Although the role of CALHM1 in AD risk remains uncertain, concordant data have now emerged showing that CALHM1 P86L is associated with an earlier age at onset of AD. Here, we have analyzed the association of CALHM1 P86L with CSF Aβ in samples from 203 AD cases and 46 young cognitively healthy individuals with a positive family history of AD. We failed to detect an association between the CALHM1 polymorphism and CSF Aβ levels in AD patients. Our data, however, revealed a significant association of CALHM1 P86L with elevated CSF Aβ42 and Aβ40 in the normal cohort at risk for AD. This work shows that CALHM1 modulates CSF Aβ levels in presymptomatic individuals, strengthening the notion that CALHM1 is involved in AD pathogenesis. These data further demonstrate the utility of endophenotype-based approaches focusing on CSF biomarkers for the identification or validation of risk factors for AD.

Frontal signal hyperintensities in mania in old age

OBJECTIVE

Signal hyperintensities (SH) on magnetic resonance (MR) imaging have been associated with increased age and with mood disorders. Frontal and subcortical neuropathology has been implicated in the pathophysiology of mania and bipolar disorders. The authors assessed frontal and subcortical SH in elderly bipolar manic patients and the comparison group, and hypothesized that SH scores would be greater in the patient group.

METHOD

MR imaging was performed in patients aged > or = 60 years with bipolar disorder, mania, and in a same-aged community comparison group. SH were rated blindly using the Boyko system. Frontal deep white matter and basal ganglia SH were assessed in the left and right hemispheres.

RESULTS

SH scores were significantly greater in patients (N = 40) than the comparison group (N = 15) in frontal deep white matter (left: p = 0.003; right: p = 0.023) based on Mann-Whitney two-sample exact tests. The SH scores in the subcortical gray regions overlapped in these groups. In patients, higher right frontal SH scores were associated with later age at onset of mania.

CONCLUSIONS

Frontal deep white matter SH may be increased in elders with bipolar disorder. Further study of the relationship of SH to age at onset in elders is warranted.

Geriatric psychiatry versus general psychiatry inpatient treatment of the elderly

OBJECTIVE

The authors compared the clinical treatment given older psychiatric inpatients on a geriatric psychiatry unit and a general psychiatry unit.

METHOD

The charts of 50 randomly selected general psychiatry inpatients over the age of 65 years and 50 inpatients from the geriatric psychiatry unit who were matched for age, gender, and primary diagnosis were reviewed.

RESULTS

Significantly greater percentages of older inpatients treated on the geriatric psychiatry unit received complete organic medical workups, structured cognitive assessment, aging-sensitive aftercare referral, and monitoring of psychopharmacological side effects and blood levels than comparable patients on a general psychiatry unit.

CONCLUSIONS

Geriatric psychiatry subspecialty inpatient care appears to be associated with distinct clinically relevant assessment and treatment advantages. Continuing geropsychiatric education of general psychiatrists is indicated.

A controlled study of MRI signal hyperintensities in older depressed patients with and without hypertension

OBJECTIVES

To compare the frequency/severity of signal hyperintensities--likely markers of cerebrovascular disease--in the subcortical gray and deep white matter on magnetic resonance imaging (MRI) scans of brains of hypertensive and normotensive older depressed and nondepressed comparison subjects.

DESIGN

Between-groups comparison of cross-sectional MRI data employing analyses of covariance controlling for the effects of age, gender, and height.

SETTING

A comprehensive inpatient-outpatient geriatric psychiatry service in a university hospital.

PARTICIPANTS

Nondemented older depressed (n = 81) and nondepressed comparison (n = 70) subjects divided into four groups (hypertensive depressed (n = 40), hypertensive normals (n = 21), normotensive depressed (n = 41), normotensive normals (n = 49)).

MEASUREMENTS

Signal hyperintensities were rated on T-2 weighted MRI scans blind to patient diagnoses employing two standardized hyperintensity rating systems (Fazekas, Boyko).

RESULTS

Hypertensive depressives had significantly more- severe hyperintensity ratings in both subcortical gray and deep white matter than did normotensive depressives and controls (P < .05) and significantly more-severe hyperintensity ratings only in subcortical gray matter (P < .05) than did hypertensive controls. Hypertensive controls had significantly more-severe ratings in deep white matter than either normotensive group (P < .05).

CONCLUSIONS

Findings suggest a relationship between deep white matter hyperintensities and hypertension (regardless of depressive state), and a particular role of subcortical gray matter hyperintensities (possibly interacting with more-severe deep white matter lesions) in older depressed hypertensives, as compared with older depressed normotensives of similar ages and severity of depression. These data support possible heterogeneous pathogenic contributions in late-life depression subgroups, one of which appears to be influenced by cerebrovascular disease.

Hippocampal/amygdala volumes in geriatric depression

BACKGROUND

The hippocampus, amygdala and related functional circuits have been implicated in the regulation of emotional expression and memory processes, which are affected in major depression. Several recent investigations have reported abnormalities in these structures in adult and elderly depressives.

METHODS

Elderly DSM-III-R unipolar depressives (N = 40) and normal controls (N = 46) participated in a magnetic resonance imaging study (1.0T). Brain images were obtained in the coronal plane. Using established anatomical guidelines for structure delineation, volumetric measurements of left and right hippocampus and anterior hippocampus/amygdala complex were completed under blinded conditions using a semi-automated computer mensuration system, with patients and controls in random order.

RESULTS

Medial temporal volumes did not significantly distinguish either elderly depressed and age-similar normal control subjects, or late onset and early onset depressed patients (ANCOVA). Major overlap of measured volumes existed between patient and control groups. In depressives, hippocampal volumes significantly correlated with age, and cognitive and depression ratings, but not with number of prior depressive episodes or age-at-onset of first depression.

CONCLUSIONS

Hippocampal volumes do not discriminate a typical clinical population of elderly depressed patients from age-similar normal control subjects. If hippocampal dysfunction contributes to a diagnosis of syndromal depression in the elderly, such dysfunction does not appear to be regularly reflected in structural abnormalities captured by volumetric measurement as conducted. On the other hand, relationships between hippocampal volumes and clinical phenomena in depressives, but not controls, suggest potentially meaningful interactions between hippocampal structure and the expression of major depression in the elderly.

Neuropsychological functioning and MRI signal hyperintensities in geriatric depression

OBJECTIVE

The purpose of this study was to examine the relationship between signal hyperintensities--a probable marker of underlying pathology--on T2-weighted magnetic resonance brain scans and neuropsychological test findings in elderly depressed and normal subjects.

METHOD

Elderly subjects with a DSM-III-R diagnosis of major depression (N=41) and normal elderly comparison subjects (N=38) participated in a magnetic resonance imaging study (1.0-T) of signal hyperintensities in periventricular, deep white matter, and subcortical gray matter. Hard copies of scans were rated in random order by research psychiatrists blind to diagnosis; the modified Fazekas hyperintensity rating scale was used. Cognitive performance was independently assessed with a comprehensive neuropsychological battery. Clinical and demographic differences between groups were assessed by t tests and chi-square analysis. Relationships between neuropsychological performance and diagnosis and hyperintensities and their interaction were analyzed by using analysis of covariance, with adjustment for age and education.

RESULTS

Elderly depressed subjects manifested poorer cognitive performance on several tests than normal comparison subjects. A significant interaction between hyperintensity location/severity and presence/absence of depression on cognitive performance was found: depressed patients with moderate-to-severe deep white matter hyperintensities demonstrated worse performance on general and delayed recall memory indices, executive functioning and language testing than depressed patients without such lesions and normal elderly subjects with or without deep white matter changes.

CONCLUSIONS

Findings validate cognitive performance decrements in geriatric depression and suggest possible neuroanatomic vulnerabilities to developing particular neuropsychological dysfunction in depressed subjects.

Neuroanatomic localization of magnetic resonance imaging signal hyperintensities in geriatric depression

BACKGROUND AND PURPOSE

Increased frequency and severity of signal hyperintensities have been regularly reported in elderly depressed patients compared with normal subjects, however, greater neuroanatomic localization of lesions has been limited.

METHODS

T2-weighted MRI scans in elderly depressed patients (n = 35) and normal comparison subjects (n = 31) were assessed for signal hyperintensities in lateralized discrete brain regions.

RESULTS

Logistic regression revealed that left frontal deep white matter (P<.005) and left putaminal (P<.04) hyperintensities significantly predicted depressive group assignment.

CONCLUSIONS

Findings suggest that greater neuroanatomic localization of hyperintensities than heretofore appreciated may relate to late-life depression.

Qualitative magnetic resonance imaging findings in geriatric depression. Possible link between later-onset depression and Alzheimer's disease?

BACKGROUND

Several clinical and neuroimaging investigations support the notion that underlying brain changes may relate to depression in older patients, especially those with a later-age initial episode. However uncertainty still exists about diagnostic and pathogenic significance of structural brain abnormalities in aged depressives, in part because many studies lack all-elderly and age-similar normal comparison populations.

METHODS

Brain morphology of elderly depressives (N = 30) and normal controls (N = 36) was compared by assessing magnetic resonance imaging (MRI) brain scans with qualitative criteria-based scales. Ratings included lateral and third ventricle enlargement, and cortical, medial temporal, and caudate atrophy.

RESULTS

Significant differences between depressed and control groups were not demonstrated. Later-onset depressives had significantly more left medial temporal and left caudate atrophy than early-onset counterparts of similar age. Medial temporal atrophy significantly correlated with cognitive impairment and was not related to physical illness. Depressives with medial temporal atrophy (N = 7) were older and had later age at onset of depression than those without such changes. Cerebrovascular disease risk factors did not predict MRI abnormalities.

CONCLUSIONS

Results indicate non-specificity and lack of homogeneity of qualitatively measured structural brain changes in geriatric depression, but suggest that pathology of specific, lateralized brain regions may be implicated in some later-onset patients. The relationship between medial temporal atrophy and late-onset depression raises the possibility that such patients may suffer from as-yet undeclared Alzheimer's disease. Lack of association between cerebrovascular disease risk factors and brain changes suggests other pathophysiological contributions.

MRI signal hyperintensities in geriatric depression

OBJECTIVE

The authors rated periventricular and subcortical signal hyperintensities on magnetic resonance imaging (MRI) scans in elderly patients with depression and in normal subjects with similar demographic features to examine whether such changes discriminate patients with depression from normal subjects and whether they are associated with any clinical variables.

METHOD

Two established hyperintensity rating systems were used to compare the MRI brain scans of 48 elderly patients with depression diagnosed according to DSM-III-R with the scans of 39 normal elderly subjects.

RESULTS

Elderly depressed patients manifested significantly more severe hyperintensity ratings in the subcortical gray matter than age-matched comparison subjects. Significant differences were not identified between patients with similar current ages and cerebrovascular disease risk who had early-onset or late-onset depression.

CONCLUSIONS

These findings support those of neuroimaging studies implicating the basal ganglia in depression and geriatric depression. The data suggest that the relationship observed in some reports between late-onset depression and MRI hyperintensities is most likely a function of cerebrovascular disease risk and age.

Tailoring adult psychiatric practices to the field of geriatrics

The United States' population is aging. Epidemiological surveys suggest significant rates of mental illness amongst the rapidly growing over-65 cohort. A burgeoning experience and data base related to the developing sub-discipline of geriatric psychiatry is now available. This article synthesizes key issues and concepts as an introduction to geropsychiatric practice-in particular, a) the interface between medical illness and psychiatric expression in the elderly, b) delirium, c) dementia, and d) depression-and considers their interactions. Finally, there is a brief overview of geriatric psychopharmacology, followed by clinically-oriented discussions of each of the major classes of psychotropics as applied to a geriatric population.

Dementia with coexistent major depression

Eleven percent (N = 25) of 232 dementia patients seen in an active geropsychiatry service also met criteria for major depression. Ten patients with dementia/depression were prospectively compared with 10 non-depressed demented and 33 nondemented depressed patients on pretreatment and posttreatment ratings of depression and cognition/memory. Seventy percent (N = 7) of the dementia/depression group and 73% (N = 24) of the depression-only group responded to antidepressant therapy. Signs and symptoms of depression complicating dementia were similar to depressive phenomena in the depression-only group. Depression with dementia appeared to lower performance on cognitive tests. Following treatment, although cognitive impairment remained in the demented range, test performance improved.

Hypochondriasis in the elderly depressed

The significance of hypochondriacal complaints in elderly depressives was explored. Sixty percent of patients had such symptoms on admission. Twelve percent were delusional. At discharge, hypochondriasis was present in 40% of the sample, with 0% delusional. Hypochondriasis was associated with anxiety (P less than .05) and somatic concerns (P less than .001), but not with complaints of depressed mood, suicidality, or short-term outcome. In dependent physical illness ratings did not correlate with hypochondriasis, however nonpsychotropic medication use did (P less than .01). Improvement in hypochondriacal complaints with treatment, yet persistence of less intense hypochondriacal concerns after remission suggests that these features may represent an admixture of state and trait phenomena in elderly depressives.

Age at onset in geriatric depression: relationship to clinical variables

The significance of age at onset of first depressive episode was evaluated in an elderly depressed population. A prospective study of 71 consecutively admitted inpatients with a diagnosis of major unipolar depression examined the relationship between age at onset of illness and several clinical variables. Subjects divided into early-onset (EO) and late-onset (LO) groups, matched for current age, did not significantly differ in terms of symptomatology, cognitive impairment, physical illness, family history or treatment responsivity. These findings do not support a nosologic separation of EO and LO depression in geriatric patients.

Cortisol and Alzheimer's disease, II: Dexamethasone suppression, dementia severity, and affective symptoms

The course of Alzheimer's disease can be complicated by depressive illness, often presenting enigmatically. To determine whether the dexamethasone suppression test (DST) can help distinguish patients with coexisting dementia and depression from those with dementia alone, DSTs were conducted with 22 nondepressed Alzheimer's disease patients. Eleven patients were nonsuppressors. The nonsuppressors were older than the suppressors but did not differ in depression or dementia ratings. The 8:00 a.m. postdexamethasone cortisol level correlated with depressive symptoms. A relationship between severity of dementia and depressive symptoms was also demonstrated.

Cortisol and Alzheimer's disease, I: Basal studies

Patients with Alzheimer's disease and nondemented elderly control subjects participated in studies of cortisol secretion during sleep and at 9:00 a.m. and were given dexamethasone suppression tests (DSTs) and lumbar punctures. Nocturnal and 9:00 a.m. cortisol concentrations were significantly higher in the demented patients. CSF MHPG negatively correlated with mean nocturnal cortisol. The most severely demented patients had the highest 9:00 a.m. and mean nocturnal cortisol concentrations. DST results did not distinguish samples with substantially different nocturnal cortisol concentrations. These results suggest that measurements of basal plasma cortisol concentrations and dexamethasone suppression provide different information but support the notion of somewhat higher than normal cortisol concentrations in Alzheimer's disease patients.

Clinical studies of the cholinergic deficit in Alzheimer's disease. II. Psychopharmacologic studies

Two studies investigated the ability of physostigmine, given both intravenously and orally, to reduce symptoms of Alzheimer's disease. Intravenous physostigmine significantly and reliably enhanced memory in 13 of 16 patients tested, but the dose producing the improvement varied among patients. Oral physostigmine decreased overall symptom severity in a reliable way in seven of 12 patients tested. The extent of improvement was correlated with the increase in mean cortisol secretion produced by physostigmine, suggesting that the drug improved behavior and cognition only to the extent that it had a specific central cholinomimetic effect. There was no significant association between response to physostigmine and results of a dexamethasone suppression test and physostigmine had no effect on growth hormone secretion.

Clinical studies of the cholinergic deficit in Alzheimer's disease. I. Neurochemical and neuroendocrine studies

Autopsy studies indicating that cholinergic neurons are selectively lost in patients with Alzheimer's disease (AD) and senile dementia of the Alzheimer type (SDAT) suggest that peripheral markers for central cholinergic activity would be useful in diagnosis. The present studies found that cerebrospinal fluid (CSF) concentrations of acetylcholine (ACh) correlated with the degree of cognitive impairment (r = .70) in a sample of carefully diagnosed patients with AD/SDAT, but metabolites of other neurotransmitters were not related to cognitive state; this suggests that CSF ACh may be a valid measure of cholinergic degeneration. Cortisol and growth hormone were measured in plasma samples drawn from patients and controls every 30 minutes from 2100 to 1100 hours the next day. Mean plasma cortisol concentrations were higher in patients with AD/SDAT than in controls and correlated inversely with CSF methoxy-hydroxyphenylglycol (MHPG) (r = .61) and positively with degree of cognitive impairment (r = +.53); as anticholinergic drugs suppress cortisol this finding indicates that cortisol dysregulation may be a marker for abnormalities in other neurotransmitter systems, particularly the noradrenergic system. Growth hormone secretion was not different in patients and controls but was positively correlated with CSF MHPG (r = +.63).

Red blood cell choline. I: Choline in Alzheimer's disease

Seventeen drug-free patients with Alzheimer's disease (AD) and 15 normal elderly controls, of which 13 age- and sex-matched pairs were included, participated in a study of red blood cell (RBC) and plasma choline. Mean values for RBC choline, plasma choline, and the ratio of RBC/plasma choline did not differ between the AD and control groups. Degree of dementia did not correlate with any blood choline measure. A correlation was found between age and RBC choline (r = 0.57; p less than or equal to 0.01) and the RBC/plasma choline ratio (r = 0.56; p less than or equal to 0.03) in normals, but not in AD patients. RBC choline correlated with plasma choline in AD patients only (r = 0.46, p less than or equal to 0.03). These results do not support the use of RBC and plasma choline concentrations as either a diagnostic tool to identify AD patients or an antemortem index of the cholinergic deficit in brains of patients with Alzheimer's disease.

Red blood cell choline. II: Kinetics in Alzheimer's disease

The kinetic parameters of choline uptake into red blood cells from patients with Alzheimer's disease and normal elderly controls were compared. The Kd and Vmax values for choline uptake into red cells were determined based on a kinetic analysis of choline uptake at six different concentrations of labeled extracellular choline. The theoretical choline uptake, representing the initial rate of choline influx into choline-depleted red cells given the plasma choline concentration and the kinetic parameters of choline uptake, was also calculated. Alzheimer's disease patients and normal controls did not differ in any kinetic parameter of choline uptake. Kd and Vmax values for red cell choline uptake were strongly correlated among normal controls, but not among patients with Alzheimer's disease. In addition, among the patients with Alzheimer's disease, the theoretical choline uptake was strongly correlated with the severity of dementia. The possible significance of these findings in relation to altered choline metabolism in Alzheimer's disease is discussed.

Oral physostigmine treatment of patients with Alzheimer's disease

Twelve patients with Alzheimer's disease received 0.0, 0.5, 1.0, 1.5, and 2.0 mg of oral physostigmine every 2 hours for 3-5 days; symptoms after each dose were assessed with the Alzheimer's Disease Assessment Scale. Placebo and the dose associated with the least severe symptoms were then readministered for 3-5 days each. Of the 10 patients who completed the study, three showed clinically significant improvement on the highest physostigmine dose in both phases, four more were marginally improved in both phases, and three had inconsistent responses to physostigmine. Cortisol measures obtained during a sleep study suggest that patients whose symptoms improved on physostigmine were those in whom oral physostigmine enhanced central cholinergic activity.

Neurotransmitter deficits in Alzheimer's disease: criteria for significance

A series of histopathologic, morphologic, and pharmacologic criteria are proposed to establish the significance of neurochemical deficits in Alzheimer's disease. The underlying pathogenic biochemistry of a better understood neurotransmitter-deficiency syndrome, Parkinson's disease, validates these criteria. The major neurotransmitter systems are evaluated against these guidelines. Only the cholinergic system fulfills all the criteria. Noradrenergic mechanisms are also implicated. Subsequent neurochemical abnormalities found in the brains of patients with Alzheimer's disease can be evaluated against these criteria.