Imaging studies and APOE genotype in persons at risk for Alzheimer’s disease

Many studies have investigated APOE-related differences in cerebral structure, blood flow, metabolism, and activation in an attempt to detect early brain changes in subjects at risk for Alzheimer’s disease (AD). Structural magnetic resonance imaging studies have produced conflicting results, with some failing to detect APOE-related differences and others suggesting that ε4 carriers have more pronounced atrophy, particularly at medial temporal structures. All functional imaging studies done during rest in middle-aged and elderly subjects have found decreased cerebral metabolism for ε4 carriers (mostly in areas that usually are affected by AD), and some have reported faster cerebral metabolic reductions over time. Areas with decreased resting cerebral perfusion and metabolism, in addition to other areas with increased perfusion, have been reported in young ε4 carriers. Imaging studies done during the performance of various cognitive tasks in middle-aged and elderly subjects, and a single study in young subjects, have produced mixed results with regionally nonspecific increased, decreased, or nondifferential APOE-related activations depending on the cognitive task used. APOE-related findings in imaging studies of nondemented subjects may be the result of incipient AD pathologic changes or of genetic heterogeneity in brain structure and function.     

Copper in Alzheimer's disease: a meta-analysis of serum,plasma, and cerebrospinal fluid studies

There is an ongoing debate on the involvement of systemic copper (Cu) dysfunctions in Alzheimer's disease (AD), and clinical studies comparing Cu levels in serum, plasma, and cerebrospinal fluid (CSF) of AD patients with those of healthy controls have delivered non-univocal and often conflicting results. In an attempt to evaluate whether Cu should be considered a potential marker of AD, we applied meta-analysis to a selection of 26 studies published in the literature. Meta-analysis is a quantitative method that combines the results of independent reports to distinguish between small effects and no effects, random variations, variations in sample used, or in different analytical approaches. The subjects' sample obtained by merging studies was a pooled total of 761 AD subjects and 664 controls for serum Cu studies, 205 AD subjects and 167 controls for plasma Cu, and of 116 AD subjects and 129 controls for CSF Cu. Our meta-analysis of serum data showed that AD patients have higher levels of serum Cu than healthy controls. Plasma data did not allow conclusions, due to their high heterogeneity, but the meta-analysis of the combined serum and plasma studies confirmed higher Cu levels in AD. The analysis of CSF data, instead, revealed no difference between AD patients and controls.     

Cerebrospinal fluid vasopressin, oxytocin, somatostatin, and beta-endorphin in Alzheimer's disease

As a first step toward assessing the status of brain neuropeptide systems that may be involved in Alzheimer's disease (AD), the cerebrospinal fluid (CSF) concentrations of the neuropeptides arginine vasopressin, somatostatin, oxytocin, and beta-endorphin were measured in patients with AD, normal elderly subjects, and normal young subjects. The plasma arginine vasopressin level was also measured in the three groups. The CSF arginine vasopressin level was significantly lower in patients with AD than in either elderly or young normal subjects, but oxytocin and beta-endorphin levels did not differ between groups. The CSF osmolarity also did not differ between groups. The plasma arginine vasopressin level did not significantly differ between groups, but high plasma arginine vasopressin values were absent in the patients with AD. The CSF somatostatin level was significantly lower in patients with AD than in normal elderly persons, but it did not differ in young normal subjects. These results suggest that central vasopressinergic activity may be decreased in AD and confirm reports of low CSF somatostatin levels in AD.     

A high incidence of apolipoprotein E ε4 allele in middle-aged non-demented subjects with cerebral amyloid β protein deposits

We examined the apolipoprotein E (ApoE) genotypes of 19 middle-aged non-demented subjects with cerebral amyloid β protein (Aβ) deposits, and compared the results with those of 16 patients with sporadic Alzheimer’s disease (AD) and those of 34 age-matched controls. The frequency of the ApoE ɛ4 allele was higher (P = 0.0256) in these 19 subjects (0.211) than in controls (0.059), and was close to that in AD patients (0.281). This result suggests that middle-aged non-demented subjects with cerebral Aβ deposits are at high risk of developing AD, and that the diffuse Aβ deposits in these cases represent an early stage of AD pathology. We speculate that in the majority of late-onset sporadic AD patients, cerebral Aβ deposition commences when these patients are in their forties or fifties, and that the pathological process progresses gradually, taking 20 to 30 years for clinical manifestation of dementia. Received: 16 March 1998 / Revised, accepted: 29 June 1998     

Elevated plasma homocysteine concentration in elderly patients with mental illness is mainly related to the presence of vascular disease and not the diagnosis

BACKGROUND: Plasma total homocysteine (tHcy) is often elevated in patients with mental illness. Since patients with mental illness and vascular disease exhibit a higher plasma tHcy concentration than patients without vascular disease, it is possible that elevated plasma tHcy in mental illness is mainly due to concomitant vascular disease. METHODS: We have investigated plasma tHcy, cobalamin/folate status, renal function and the presence of vascular disease in patients with vascular dementia (VaD, n = 501), Alzheimer's disease (AD, n = 300), depression (n = 259) and in healthy subjects (n = 144) stratified according to age (below and above 75 years). RESULTS: Plasma tHcy concentration showed the highest increase in patients with VaD compared to patients with AD or depression. After the exclusion of patients with cobalamin/folate deficiencies and increased serum creatinine, patients with AD or depression above 75 years with vascular disease showed a similar elevation of plasma tHcy concentration as patients with VaD. Furthermore, patients with AD and depression without vascular disease showed a similar plasma tHcy concentration to healthy subjects. CONCLUSION: The findings imply that elevated plasma tHcy concentration in elderly patients with mental illness is mainly associated with the presence of vascular disease and is not related to the specific psychogeriatric diagnosis.     

Oxidative damage, protein synthesis, and protein degradation in Alzheimer's disease

A large number of studies has firmly established that increases in oxidative damage occurs in Alzheimer's disease (AD). Such studies have demonstrated that increased in oxidative damage selectively occurs within the brain regions involved in regulating cognitive performance. Studies from our laboratory and others have provided experimental evidence that increased levels of oxidative damage occur in subjects with Mild Cognitive Impairment (MCI), which is believed to be one of the earliest stages of AD, and is a condition which is devoid of dementia or the extensive neurofibrillary pathology and neuritic plaque deposition observed in AD. Together, these data support a role for the accrual of oxidative damage potentially serving as an early event that then initiates the development of cognitive disturbances and pathological features observed in AD. Recent studies from our laboratory have demonstrated that a decline in protein synthesis capabilities occurs in the same brain regions which exhibit increased levels of oxidative damage in MCI and AD subjects. The focus of this review is to describe the large number of studies which suggest protein synthesis may be one of the earliest cellular processes disrupted by oxidative damage in AD. Taken together, these findings have important implications for understanding the molecular and cellular basis of AD, understanding the basis for oxidative stress in AD, and may have important implications for studies involving proteomics and proteolysis in AD.     

Manganese and Copper-Zinc Superoxide Dismutases in the Human Olfactory Mucosa: Increased Immunoreactivity in Alzheimer's Disease

Superoxide dismutases are the cell's major enzymatic defenses against cytotoxic reactive oxygen species and oxidative stress. Reactive oxygen species, which induce the expression of these enzymes, have been implicated in the neurodegeneration associated with Alzheimer's disease (AD), and individuals with AD exhibit early, severe deficits in olfactory ability. We used immunohistochemistry to examine the cellular localization of manganese and copper-zinc superoxide dismutases in the olfactory mucosae of nondemented young/middle-aged and old subjects as well as age- and postmortem-interval matched nondemented elderly individuals and those with AD. Tissues were obtained at autopsy from individuals ranging in age from 19 to 98 years old. Immunoreactivity for both enzymes was localized in olfactory receptor neurons, sustentacular and basal cells in the olfactory epithelium, and in olfactory and extrinsic nerves, Bowman's glands, and vascular endothelium in the lamina propria. Computer-assisted quantitative analysis demonstrated that very intense immunoreactivity for both manganese and copper-zinc superoxide dismutases occupied significantly more area, particularly near the surface and in the basal region, of the olfactory epithelium from subjects with AD than from the age- and postmortem interval-matched nondemented elderly subjects. The pronounced increase in superoxide dismutase immunoreactivity in the olfactory epithelium of AD subjects suggests that oxidative stress may be responsible, at least in part, for the olfactory deficits in subjects with AD.     

Pigment Epithelium-Derived Factor Plays a Role in Alzheimer’s Disease by Negatively Regulating Aβ42

Alzheimer’s disease (AD) is the most common cause of dementia. Pigment epithelium-derived factor (PEDF), a unique neurotrophic protein, decreases with aging. Previous reports have conflicted regarding whether the PEDF concentration is altered in AD patients. In addition, the effect of PEDF on AD has not been documented. Here, we tested serum samples of 31 AD patients and 271 normal controls. We found that compared to PEDF levels in young and middle-aged control subjects, PEDF levels were reduced in old-aged controls and even more so in AD patients. Furthermore, we verified that PEDF expression was much lower and amyloid β-protein (Aβ)42 expression was much higher in senescence-accelerated mouse prone 8 (SAMP8) strain mice than in senescence-accelerated mouse resistant 1 (SAMR1) control strain mice. Accordingly, high levels of Aβ42 were also observed in PEDF knockout (KO) mice. PEDF notably reduced cognitive impairment in the Morris water maze (MWM) and significantly downregulated Aβ42 in SAMP8 mice. Mechanistically, PEDF downregulated presenilin-1 (PS1) expression by inhibiting the c-Jun N-terminal kinase (JNK) pathway. Taken together, our findings demonstrate for the first time that PEDF negatively regulates Aβ42 and that PEDF deficiency with aging might play a crucial role in the development of AD.     

The 5-HTTPR polymorphism confers liability to a combined phenotype of psychotic and aggressive behavior in Alzheimer disease

BACKGROUND: Psychotic symptoms in subjects with Alzheimer disease (AD+psychosis, AD+P) are a marker for a distinct phenotype characterized by more rapid cognitive and functional decline and a liability to aggressive behaviors. We recently found that AD subjects homozygous for long alleles (l) of an insertion/deletion polymorphism in the promoter region of the serotonin transporter (5-HTTPR) had elevated rates of aggressive behavior. OBJECTIVE: To examine whether the 5-HTTPR ll genotype confers an increased risk of AD+P, and of the combined AD+P/aggressive phenotype. METHODS: The 5-HTTPR genotype was determined in 332 subjects diagnosed with possible or probable AD. All subjects received structured psychiatric assessments and were categorized with regard to their history of aggressive behaviors and psychotic symptoms. RESULTS: Consistent with other reports, AD+P was associated with a significant increased risk for aggressive behavior. AD+P and aggression were both significantly associated with 5-HTTPR ll genotype and with an increased l allele frequency. Subjects with the combined behavioral phenotype (AD+P and aggressive behavior) had the highest rate of ll genotype and highest l allele frequency. CONCLUSION: The 5-HTTPR l allele appears to confer risk for the combined AD+P/aggressive phenotype. Confirmation of this association in a similar behaviorally well-characterized independent sample is needed.     

Effects of Alzheimer's disease and gender on the hypothalamic-pituitary-adrenal axis response to lumbar puncture stress.

Differences in hypothalamic-pituitary-adrenal (HPA) axis responsiveness to lumbar puncture (LP) stress were studied in normal elderly subjects and Alzheimer's disease (AD) patients of both genders. Elderly normal subjects had larger peak cortisol and ACTH responses than AD patients. These results contrast with some previous reports of increased HPA-axis responsivity associated with AD and suggest that AD-related changes in HPA responsiveness depend on the type of stressor involved and are mediated 'upstream' to the final common pathway to ACTH secretion. HPA-axis responsiveness also differed by gender, with higher peaks and prolonged elevations in elderly female subjects than in elderly males.     

"Preclinical" AD revisited: neuropathology of cognitively normal older adults

OBJECTIVE: To classify neuropathologic alterations in the brains of nondemented older adults using current sets of criteria for AD. BACKGROUND: AD neuropathologic alterations are found in the brains of some nondemented elderly subjects and suggest the possibility of presymptomatic AD. Three sets of guidelines have been developed to classify AD using senile plaques, neuritic plaques, and neurofibrillary tangles (NFT). METHODS: Neuropathologic changes in 59 older adults followed longitudinally with a standard battery of mental status measures were investigated using Khachaturian, Consortium to Establish a Registry for Alzheimer's Disease (CERAD), and National Institute on Aging-Reagan Institute (NIA-RI) guidelines. AD neuropathologic markers were evaluated in neocortical and allocortical regions. Cases were categorized as neuropathologically "normal" or "AD-like" and compared for possible mental status differences. RESULTS: Between 11 and 49% of cases met one or more of the three classifications of AD. With adjustments for multiple comparisons, only NFT in hippocampal CA1 region were associated with autopsy age, suggesting that this may represent a pathologic process associated with normal brain aging. Using the NIA-RI guidelines, subjects in the AD-like group performed less well on the immediate paragraph recall and word-list delayed recall than their counterparts who did not meet these guidelines. CONCLUSIONS: These data indicate that the prevalence of "preclinical" AD in our population is relatively low based on the NIA-RI classification. Although many subjects had AD-like changes based on CERAD and Khachaturian guidelines, they exhibited no differences in mental performance, suggesting that the aging brain may be able to withstand such structural changes without meaningful impact on mental functioning.     

Blood levels of histamine,IL-1β, and TNF-α in patients with mild to moderate alzheimer disease

In this study, we have evaluated the levels of blood histamine, serum interleukin-1 beta (IL-1β), and plasma tumor necrosis factor-alpha (TNF-α) in 20 patients with mild to moderate Alzheimer disease (AD; 13 early onset and 7 late-onset AD subjects) and in 20 agematched control subjects (C). AD patients showed higher concentrations of histamine (AD=452.9±237.9 pmol/mL; C=275.3±151.5 pmol/mL;p<0.05) and IL-1β (AD=211.2±31.1 pg/mL; C=183.4±24.4 pg/mL;p<0.01), and lower values of TNF-α (AD=3.59±2.02 pg/mL; C=9.47±2.64 pg/mL;p<0.001) than elderly controls. Increased levels of histamine and decreased levels of TNF-α were observed in both early onset AD (EOAD) and late-onset AD (LOAD) patients, but only EOAD subjects had elevated serum IL-1β values compared with age-matched controls. Age negatively correlated with histamine (r=?0.57;p<0.05) and positively with IL-1β levels (r=0.48;p<0.05) in healthy subjects, but not in AD, whereas a positive correlation between TNF-α scores and age was only found in AD patients (r=0.46;p<0.05). Furthermore, histamine and TNF-α values correlated negatively in AD (r=?0.50,p<0.05). In addition, cognitive impairment increased in patients with lower TNF-α and higher histamine and IL-1β levels, as indicated by the correlations between mental performance scores and histamine (r=?0.37, ns), IL-1β (r=?0.33, ns) and TNF-α levels (r=0.42,p<0.05). Finally, histamine concentrations decreased as depression scores increased in AD (r=?0.63,p<0.01). These data suggest a dysfunction in cytokine and histamine regulation in AD, probably indicating changes associated with inflammatory processes.     

Evidence for an interaction between apolipoprotein E genotype, gender, and Alzheimer disease

Carriers of the apolipoprotein E (APOE) epsilon4 allele show significantly higher risk of Alzheimer disease (AD). The aim of this present study was to test the hypothesis that a significant interaction exists between APOE genotype and gender on AD. Interactions of epsilon4 by gender, although indicated in the literature, require further verification. A total of 195 past or current control or AD participants in an ongoing longitudinal study of aging and dementia were genotyped. All subjects were at least 60 years old; demented subjects met clinical or pathologic criteria for late-onset AD. Logistic regression analysis and proportional hazard models were used to evaluate joint effects of APOE and gender. A significant statistical interaction between APOE and gender was shown (p = 0.04) in logistic regression analysis. Women carrying one or more APOE-epsilon4 allele were more likely to develop AD [odds ratio (OR) = 7.8, 95% confidence interval (CI) = 3.2-19. 1]. For men, the presence of the APOE-epsilon4 allele was not associated with a statistically significant increased risk (OR = 1.6, 95% CI = 0.5-5.3). The interaction term in the proportional hazards model neared (p = 0.07) statistical significance, and a similar but reduced gender effect was shown. The analysis suggests that the presence of one or more APOE-epsilon4 allele confers a substantially greater risk of AD to women than to men. These findings in part may account for reports of increased risk of AD faced by women.     

Cerebrospinal fluid cortisol concentrations in healthy elderly are affected by both APOE and TOMM40 variants

Abnormalities of the hypothalamic-pituitary-adrenal (HPA) axis have been reported in subjects with Alzheimer's disease (AD) and may include increased cerebrospinal fluid (CSF) cortisol concentrations. Moreover, presence of the APOE ?4 allele, which is an established risk factor for the development of AD, has been shown to associate with higher CSF cortisol levels, especially in AD sufferers. In this study, we examined whether TOMM40 variants, which have been reported to influence age of onset of AD, also had an effect on CSF cortisol levels, in healthy, cognitively intact individuals with or without APOE ?4. In our results, the increase in CSF cortisol associated with the presence of the APOE ?4 allele was only detected when a short TOMM40 poly-T variant, shown to associate with later age of onset of AD in ?4 carriers, was not present. These results are consistent with previous reports (e.g., Roses et al., 2009) suggesting that TOMM40 poly-T variants influence the effects of APOE alleles.     

The perceived coerciveness of involuntary outpatient commitment: findings from an experimental study

This study examines self-reported coercion in subjects with severe mental illness who were randomly assigned in an experimental study to continue under, or be released from, involuntary outpatient commitment (OPC) subsequent to hospital discharge. After review of bivariate relationships, multivariable analyses demonstrated significantly higher levels of reported coercion among subjects who experienced longer periods of OPC; who were African American; who were single and not cohabiting; and who had ongoing substance abuse problems, poor insight into illness, and severe symptoms. Case managers' verbal reminders to subjects about the consequences of nonadherence to treatment partially account for higher reports of coercion. Previous reports from this study have found that OPC, if sustained and combined with frequent outpatient mental health services, can improve some outcomes. The current analyses demonstrate that a consequence of OPC is increased perceptions of coercion in the treatment process, which is partially explained by the increased attention by case managers to noncompliance with treatment.     

Decrease in brain soluble amyloid precursor protein β (sAPPβ) in Alzheimer's disease cortex

Amyloid-β peptide (Aβ) is generated by sequential cleavage of the amyloid precursor protein (APP) by β-site amyloid precursor protein cleaving enzyme 1 (β-secretase, or BACE1) and γ-secretase. Several reports demonstrate increased BACE1 enzymatic activity in brain and cerebrospinal fluid (CSF) from Alzheimer's disease (AD) subjects, suggesting that an increase in BACE1-mediated cleavage of APP drives amyloid pathophysiology in AD. BACE1 cleavage of APP leads to the generation of a secreted N-terminal fragment of APP (sAPPβ). To relate BACE1 activity better to endogenous APP processing in AD and control brains, we have directly measured brain sAPPβ levels using a novel APP β-site specific enzyme-linked immunosorbent assay. We demonstrate a significant reduction in brain cortical sAPPβ levels in AD compared with control subjects. In the same brain samples, BACE1 activity was unchanged, full-length APP and sAPPα levels were significantly reduced, and Aβ peptides were significantly elevated. In conclusion, a reduction in cortical brain sAPPβ together with unchanged BACE1 activity suggests that this is due to reduced full-length APP substrate in late-stage AD subjects. These results highlight the need for multiparameter analysis of the amyloidogenic process to understand better AD pathophysiology in early vs. late-stage AD.     

Cortical cathepsin D activity and immunolocalization in Alzheimer disease, critical coronary artery disease, and aging

The activity and immunocytochemical localization of cathepsin D in the frontal cortex were investigated in patients with Alzheimer disease (AD) and two groups of nondemented subjects; individuals with critical coronary artery disease (cCAD; >75% stenosis) and nonheart disease controls (non-HD). The cathepsin D activity significantly increased with age in the non-HD population. No such age-related increase was observed in either AD or cCAD. Enzymatic activity was significantly increased in only the midaged, but not the older AD and cCAD subjects compared to controls. Immunocytochemical reactivity paralleled cathepsin D enzymatic activity. Frontal cortex neurons displayed an increased accumulation of cathepsin D immunoreactivity in aging (non-HD controls) with a further increase in cCAD, especially in the midaged group. Such immunoreactivity was markedly increased in AD. There was also an apparent age-related increase in the number of cathepsin D immunoreactive neurons in the non-HD population and a disease-related increase in only the mid-aged AD and cCAD subjects compared to controls. Senile plaques (SP) occured in all AD patients, many cCAD, and a few of the oldest non-HD subjects, and they were immunoreactive to cathepsin D in each group. The data suggest a possible relationship between activation of cathepsin D and SP formation in AD, cCAD, and aging.     

Abstinence, occasional drinking and binge drinking in middle-aged women. The Women's Health in Lund Area (WHILA) Study

Although drinking patterns in women have received increased attention, few studies have focused on middle-aged women. Drinking patterns were investigated in a population sample of 513 Swedish women aged 50-59, and analysed in relation to social situation, and mental and physical health. The chi-square test was used to analyse differences in proportions. Variables showing significant differences were entered into a multivariate or multinomial logistic regression model. Abstainers and occasional drinkers had lower levels of education and more often regular medical control compared with weekly drinkers. Furthermore, abstainers more often had disability pension. Among women drinking alcohol, 56.6% affirmed binge drinking within the last year and 39.4% within the last month. Binge drinkers did not differ in terms of social situation, mental or physical health, compared with other drinkers. Drinking to relieve tension was affirmed by 7.2%. These women had more mental symptoms and less contact with friends compared with other drinkers; furthermore, they were more often binge drinkers. Binge drinking was common and health and social consequences of this drinking pattern in middle-aged women need to be further explored. Women drinking to relieve tension may need intervention for both drinking habits and mental health.     

Effects of periodic leg movements during sleep in middle-aged subjects without sleep complaints.

Recent reports have called into question the relevance of periodic leg movements during sleep disorder (PLMSD) as a specific clinical entity. Because periodic leg movement in sleep index (PLMSI) increases with age, it has become an important exclusion criterion in research on aging. However, it is unknown if PLMSI is related to sleep quality in middle-aged subjects without sleep complaints. The sleep of 70 healthy, middle-aged subjects (age 40 to 60 years) without sleep complaints was evaluated. Subjects were divided into two groups according to their PLMSI severity: (1) 43 subjects (28 women, 15 men) were in the low PLMSI group (<5) and (2) 22 subjects (9 women, 13 men) were in the high PLMSI group (>10). A significantly higher proportion of men than women showed PLMSI greater than 5. There was no significant effect of PLMSI severity group for polysomnographic sleep parameters. PLMSI exerted a small but significant effect on subjective sleep quality, especially in middle-aged men. These results raise questions about the relevance of PLMSI as a pathological index for middle-aged subjects without sleep complaints and support the notion that an increase in PLMSI may be part of the normal process of aging associated with the loss of dopaminergic function.     

阿尔茨海默病患者尿中AD7c-NTP含量的研究

目的探讨尿中阿尔茨海默病相关神经丝蛋白(AD7c-NTP)含量在阿尔茨海默病(AD)诊断中的意义。方法采用直接竞争性酶联免疫吸附测定法(ELISA),检测218例老年人,其中AD组46例、血管性痴呆组(VD组)50例、智能正常老年对照组122例尿液中AD7c-NTP含量,所有数据均经过SPSS软件进行统计学处理。结果AD组、VD组及智能正常老年对照组尿液中AD7c-NTP含量分别为33.35±1.61、18.19±1.41、18.30±1.45μg/ml,AD组明显高于其他两组,而VD组与智能正常老年对照组差异无统计学意义(P>0.05);91.4%的AD病例AD7c-NTP含量升高((22μg/ml),非AD病例中90.7%均为正常(?22μg/ml)。结论尿液中AD7c-NTP含量检测作为无创性检查,在AD诊断中具有重要的临床参考价值。