Longitudinal study of quality of life in people with advanced Alzheimer's disease

The authors examined three indicators of health-related quality of life in people with advanced Alzheimer's disease ([AD]; N=150): confinement to home, null activity, and null positive affect, as reported by patient proxies. Dementia severity predicted time-to-onset for all three disease milestones in models that controlled for sociodemographic indicators, nursing home status, and death in the follow-up period. Patients whose dementia worsened over follow-up were more likely to reach each milestone. These outcomes represent key milestones in the care of patients; they are sensitive to disease progression, and they are likely to be useful for studying treatment in advanced AD.

Beta-amyloid activates the mitogen-activated protein kinase cascade via hippocampal alpha7 nicotinic acetylcholine receptors: In vitro and in vivo mechanisms related to Alzheimer's disease

Alzheimer's Disease (AD) is the most common of the senile dementias, the prevalence of which is increasing rapidly, with a projected 14 million affected worldwide by 2025. The signal transduction mechanisms that underlie the learning and memory derangements in AD are poorly understood. beta-Amyloid (Abeta) peptides are elevated in brain tissue of AD patients and are the principal component of amyloid plaques, a major criterion for postmortem diagnosis of the disease. Using acute and organotypic hippocampal slice preparations, we demonstrate that Abeta peptide 1-42 (Abeta42) couples to the mitogen-activated protein kinase (MAPK) cascade via alpha7 nicotinic acetylcholine receptors (nAChRs). In vivo elevation of Abeta, such as that exhibited in an animal model for AD, leads to the upregulation of alpha7 nAChR protein. alpha7 nAChR upregulation occurs concomitantly with the downregulation of the 42 kDa isoform of extracellular signal-regulated kinase (ERK2) MAPK in hippocampi of aged animals. The phosphorylation state of a transcriptional mediator of long-term potentiation and a downstream target of the ERK MAPK cascade, the cAMP-regulatory element binding (CREB) protein, were affected also. These findings support the model that derangement of hippocampus signal transduction cascades in AD arises as a consequence of increased Abeta burden and chronic activation of the ERK MAPK cascade in an alpha7 nAChR-dependent manner that eventually leads to the downregulation of ERK2 MAPK and decreased phosphorylation of CREB protein.

Absence of mitochondrial superoxide dismutase results in a murine hemolytic anemia responsive to therapy with a catalytic antioxidant

Manganese superoxide dismutase 2 (SOD2) is a critical component of the mitochondrial pathway for detoxification of O2(-), and targeted disruption of this locus leads to embryonic or neonatal lethality in mice. To follow the effects of SOD2 deficiency in cells over a longer time course, we created hematopoietic chimeras in which all blood cells are derived from fetal liver stem cells of Sod2 knockout, heterozygous, or wild-type littermates. Stem cells of each genotype efficiently rescued hematopoiesis and allowed long-term survival of lethally irradiated host animals. Peripheral blood analysis of leukocyte populations revealed no differences in reconstitution kinetics of T cells, B cells, or myeloid cells when comparing Sod2(+/+), Sod2(-/-), and Sod2(+/-) fetal liver recipients. However, animals receiving Sod2(-/-) cells were persistently anemic, with findings suggestive of a hemolytic process. Loss of SOD2 in erythroid progenitor cells results in enhanced protein oxidative damage, altered membrane deformation, and reduced survival of red cells. Treatment of anemic animals with Euk-8, a catalytic antioxidant with both SOD and catalase activities, significantly corrected this oxidative stress-induced condition. Such therapy may prove useful in treatment of human disorders such as sideroblastic anemia, which SOD2 deficiency most closely resembles.

Prognostic importance of the axillary lymph node ratio in autologous transplantation for high-risk stage II/III breast cancer

The role of autologous peripheral blood progenitor cell (PBPC) transplantation for high-risk stage II/III breast cancer remains controversial. New prognostic indicators defining subsets of patients who may benefit from autologous PBPC transplantation would be clinically useful. The axillary lymph node ratio, defined by the total number of axillary nodes involved with cancer divided by the number of axillary nodes surgically sampled, has been reported to be of potential prognostic importance in transplantation for high-risk, stage II/III breast cancer. We therefore retrospectively reviewed 111 women with high-risk, stage II/III breast cancer with at least four positive axillary lymph nodes undergoing autologous PBPC transplantation from 1991 to June 1999. None of the patients had received prior radiotherapy and all had completed one, and only one, course of at least three cycles of adjuvant chemotherapy. The median number of axillary nodes sampled was 20 (range 6-40) and the median number of positive axillary nodes was 12 (range 4-35). The median node ratio, dividing the number of positive nodes by the number of sampled nodes, was 0.68. Event-free survival was strongly influenced by node ratio. Patients having a node ratio of < 0.7 had a 5-year event-free survival of 68%, vs those with a node ratio of > or = 0.7 with a 5-year event-free survival of 46% (P = 0.03). Forty percent of patients with a high node ratio have relapsed vs 20% with a low node ratio (P = 0.02). Multivariate analysis revealed that positive estrogen receptor status and a node ratio of < 0.7 were independent factors related to better event-free survival (P = 0.0001 and P = 0.004, respectively). We conclude that patients having a node ratio of < 0.7 have a significantly better prognosis following autologous PBPC transplantation than do patients with a ratio > or = 0.7.

Characterization of baboon (Papio hamadryas) milk proteins

The major proteins of baboon milk were identified as beta-lactoglobulin (beta LG), alpha-lactalbumin (alpha LA), lysozyme, lactoferrin, casein, and albumin by immobiline isoelectric focusing, SDS-PAGE, immunoblotting of gels with rabbit antisera to human alpha LA, lysozyme, and albumin and bovine beta LG and casein, and N-terminal sequencing of proteins blotted from gels. The first 30 N-terminal residues of baboon beta LG are identical to those of macaque (Macaca fasicularis) beta LG except for a (D/N) polymorphism at residue 2. The complete cDNA sequence and derived amino acid composition of beta LG were elucidated using RT-PCR amplification of poly(A)+ mRNA purified from lactating mammary gland. Baboon beta LG consists of 168 amino acid residues (M(r) 20,750) and is the longest beta LG identified to date. beta LG and alpha LA polymorphisms with three (A, B, and C) and two (A and B) variants, respectively, were detected by immobiline IEF, pH 4-6, of individual baboon milk samples at varying stages of lactation.

Incidence of AD in African-Americans, Caribbean Hispanics, and Caucasians in northern Manhattan

OBJECTIVE

To compare the incidence rates for AD among elderly African-American, Caribbean Hispanic, and white individuals and to determine whether coincident cerebrovascular disease contributes to the inconsistency in reported differences among ethnic groups.

METHODS

This was a population-based, longitudinal study over a 7-year period in the Washington Heights and Inwood communities of New York City. Annual incidence rates for AD were calculated and compared by ethnic group, and cumulative incidence adjusted for differences in education, diabetes, cardiovascular risk factors, and stroke was calculated.

RESULTS

The age-specific incidence rate for probable and possible AD was 1.3% (95% CI, 0.8 to 1.7) per person-year between the ages of 65 and 74 years, 4.0% (95% CI, 3.2 to 4.8) per person-year between ages 75 and 84 years, and 7.9% (95% CI, 5.5 to 10.5) per person-year for ages 85 and older. Compared to white individuals, the cumulative incidence of AD to age 90 years was increased twofold among African-American and Caribbean Hispanic individuals. Adjustment for differences in number of years of education, illiteracy, or a history of stroke, hypertension, heart disease, or diabetes did not change the disproportionate risks among the three ethnic groups.

CONCLUSION

The incidence rate for AD was significantly higher among African-American and Caribbean Hispanic elderly individuals compared white individuals. The presence of clinically apparent cardiovascular or cerebrovascular disease did not contribute to the increased risk of disease. Because the proportion of African-American and Caribbean Hispanic individuals reaching ages 65 and older in the United States is increasing more rapidly than the proportion of white individuals, it is imperative that this disparity in health among the elderly be understood.

Contributions of soil and crop factors to plant available soil water capacity of annual crops on Black and Grey Vertosols

Improved methods for field measurements of plant available soil water capacity (PAWC) of Black and Grey Vertosols in Australia’s north-eastern grain region were employed to characterise 83 soil–crop combinations over 7 depth intervals to 180 cm. Soil sub-order was shown to influence all components of PAWC (means of 224 and 182 mm in Black and Grey Vertosols, respectively) with drained upper limit (DUL), bulk density (BD), and crop lower limits (CLL) showing clear separation between soil sub-orders and a trend with soil depth. In addition to soil sub-order and soil depth effects, CLL showed crop effects such that expected PAWC of various crops when adjusted for soil sub-orders were: cotton 240 mm; wheat 233 mm; sorghum 225 mm; fababean 209 mm; chickpea 197 mm; barley 191 mm; and mungbean 130 mm. A total of 549 measured CLL values were used to develop a predictive model for estimating CLL from the soil sub-order, depth, DUL, and crop by predicting a CLL as a function of DUL and a depth-dependent variable for each crop–soil sub-order. The model CLL = DUL * (a + b * DUL) explained 85% of observed variation in the measured data with no significant bias between observed and predicted data. While properly measured data would be more reliable than estimated data, where specific site accuracy is less critical, this model may be used to estimate PAWC with an acceptable degree of accuracy.

Different brain networks mediate task performance in normal aging and AD: defining compensation

OBJECTIVE

To determine whether the pathologic mechanisms of AD alter the brain networks subserving performance of a verbal recognition task.

BACKGROUND

Functional imaging studies comparing task-related activation in AD patients and controls generally have not used network analysis and have not controlled for task difficulty.

METHODS

H2 15O PET was used to measure regional cerebral blood flow in 14 patients and 11 healthy elders during the performance of a serial verbal recognition task under two conditions: low demand, with study list size (SLS) equal to one; and titrated demand, with SLS adjusted so that each subject recognized words at 75% accuracy. The Scaled Subprofile Model was used to identify networks of regionally covarying activity across these task conditions.

RESULTS

In the elders, higher SLS was associated with the recruitment of a network of brain areas involving left anterior cingulate and anterior insula (R2 = 0.94; p < 0.0001). Three patients also expressed this network. In the remaining patients, higher SLS was associated with the recruitment of an alternate network consisting of left posterior temporal cortex, calcarine cortex, posterior cingulate, and the vermis (R2 = 0.81, p < 0.001). Expression of this network was unrelated to SLS in the elders and more intact AD patients.

CONCLUSIONS

The patients' use of the alternate network may indicate compensation for processing deficits. The transition from the normal to the alternate network may indicate a point where brain disease has irreversibly altered brain function and thus may have important implications for therapeutic intervention.

The role of routine laboratory studies and neuroimaging in the diagnosis of dementia: a clinicopathological study

OBJECTIVE

To determine the neuropathological diagnoses of longitudinally followed patients with potentially reversible causes of dementia and to examine the results of the "dementia work-up," especially neuroimaging, by comparison with the pathological diagnosis.

DESIGN

A neuropathologic series of 61 consecutive patients, with review of clinical, laboratory, neuroimaging, and pathological results.

RESULTS

Of the 61 patients, forty-eight (79%) had a clinical diagnosis of probable or possible Alzheimer's disease (AD). Compared with the pathological diagnosis, the sensitivity and specificity of the clinical diagnosis of AD were 96% and 79%, respectively. Of the 61 patients, 9 had abnormal laboratory tests, the correction of which did not improve the subsequent course. These patients were found to have AD8 and frontotemporal dementia on pathology. In two patients, neuroimaging was helpful in the clinical diagnoses of frontotemporal dementia and progressive supranuclear palsy (PSP). Neuroimaging revealed cerebrovascular disease in 18 patients, only two of whom were suspected clinically. Pathology confirmed AD in 17 and PSP in 1 of these patients. Sensitivity and specificity for the clinical diagnosis of cerebrovascular disease in comparison with pathology were 6% and 98%, respectively. With the added information from neuroimaging, that sensitivity increased to 59% and specificity decreased to 81%.

CONCLUSIONS

All cases with abnormal laboratory or neuroimaging results had AD or some other neurodegenerative disease on pathology. The "dementia work-up" did not reveal any reversible causes for dementia in this group of patients. Neuroimaging may have a role, especially in the diagnosis of possible AD with concomitant cerebrovascular disease.

Context-specific enhancement of glutamate transmission by cocaine

The repeated injection of cocaine causes an increase in the capacity of a subsequent acute injection to elevate extracellular glutamate levels in the nucleus accumbens, and the present study sought to determine if the elevation in extracellular glutamate is regulated by the pairing of environmental stimuli with drug administration. Three treatment groups were injected daily for seven days with saline or cocaine (15 mg/kg, ip); 1) injection of saline in the home cage, 2) injection of cocaine in the home cage (cocaine-unpaired), and 3) injection of cocaine in the test apparatus (cocaine-paired). Three weeks following the last daily injection dialysis probes were placed into the nucleus accumbens and all rats were injected with saline followed by cocaine. Basal levels of extracellular glutamate were significantly reduced in the cocaine-paired treatment group. Moreover, only in the cocaine-paired group did the cocaine injection elevate extracellular glutamate. Repeated administration of cocaine also produces an enduring increase in the motor stimulant response to an acute cocaine injection and it was previously found that administration of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid and kainic acid glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2, 3-dione inhibited the sensitized, but not the acute motor, response to cocaine. In this study it was found that the motor stimulant response elicited by cocaine was blunted by pretreatment of the nucleus accumbens with 6-cyano-7-nitroquinoxaline-2,3-dione only in animals receiving daily cocaine injections in the paired environment. In contrast, the N-methyl-D-aspartate glutamate receptor antagonist R-(-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid did not significantly affect cocaine-induced motor activity in any treatment group. These data support a hypothesis that environmental stimuli previously associated with daily cocaine administration can modulate glutamate transmission in the nucleus accumbens in a manner affecting cocaine-induced behavior.

Olfactory deficits in patients with mild cognitive impairment predict Alzheimer's disease at follow-up

OBJECTIVE

This study evaluated the predictive utility of olfactory identification deficits in patients with mild cognitive impairment for follow-up diagnosis of probable Alzheimer's disease.

METHOD

Ninety outpatients with mild cognitive impairment were examined at 6-month intervals. Matched healthy comparison subjects (N=45) were examined annually. The University of Pennsylvania Smell Identification Test was given at baseline.

RESULTS

Olfaction scores were lower in patients with mild cognitive impairment than in healthy comparison subjects. Seventy-seven patients were followed up; 19 were diagnosed with Alzheimer's disease by 2 years. Patients with low olfaction scores (< or =34 of 40), and patients with low olfaction scores who reported no subjective problems smelling, were more likely to develop Alzheimer's disease than other patients. In a Cox proportional hazards model adjusted for age, sex, modified Mini-Mental State score, and education, low olfaction scores did not predict time until development of Alzheimer's disease, but low olfaction scores accompanied by lack of awareness of olfactory deficits predicted time to development of Alzheimer's disease. This effect remained when attention or memory measures replaced modified Mini-Mental State score in the model. In patients with high Mini-Mental State scores (> or =27 of 30), low olfaction with lack of awareness remained a significant predictor of Alzheimer's disease. Olfaction scores of 30-35 showed moderate to strong sensitivity and specificity for diagnosis of Alzheimer's disease at follow-up.

CONCLUSIONS

In patients with mild cognitive impairment, olfactory identification deficits, particularly with lack of awareness of olfactory deficits, may have clinical utility as an early diagnostic marker for Alzheimer's disease.

The identification of a potent imidazoline-based vascular K(ATP) channel antagonist

In this study the activity of a number of novel imidazoline-based compounds (IMID series) was assessed by functional and binding studies to determine their actions at K(ATP) channels. The novel compounds, which we synthesised, were methoxy-, methyl-, butyl- and fluorophenyl derivatives of clonidine. In functional studies we determined the potency (by calculating a pK(B) value) of the IMID compounds to antagonise levcromakalim responses in segments of isolated pig coronary artery. The most potent compounds identified (laboratory codes: IMID-1M, IMID-26F and IMID-4F) had apparent pK(B) values of approximately 7 which is similar to that for the sulphonylurea, glibenclamide and the lipophilic quaternary ion, tetraphenylphosphonium. This inhibitory action was specific for levcromakalim since the imidazoline antagonist IMID-1M failed to effect vasorelaxation response-curves to the non-KATP channel opener, sodium nitroprusside. In the spontaneously beating rat right atrium preparation the majority of the compounds were able to cause slowing of heart rate, but with low EC50 values (approximately 10-30 microM). In binding studies, the compounds were unable to displace binding of [3H]P1075 to bovine aortic smooth muscle preparations nor [3H]glibenclamide binding to rat cerebral cortex membranes. These studies show that some imidazoline-based compounds are potent antagonists of levcromakalim-mediated vasorelaxation responses in the pig coronary artery. The compounds displayed only minimal bradycardic activity. The site of action of the imidazoline compounds does not appear to be the same as that used by K(ATP) channel openers or sulphonylurea-based antagonists. It is likely that these compounds interact with the K(ATP) channel pore itself.

The effect of pre-operative topical flurbiprofen or diclofenac on pupil dilatation

PURPOSE

To assess the clinical benefit and relative efficacy of pre-operative diclofenac and flurbiprofen drops in routine cataract surgery.

METHODS

Fifty-two patients undergoing extracapsular cataract extraction with lens implantation were randomised in a double-masked study to compare the efficacy of diclofenac, flurbiprofen and placebo drops in maintaining per-operative mydriasis and reducing post-operative inflammation. Balanced salt solution containing adrenaline was used in all patients. Pupil size was measured prior to the corneal section and after the completion of the operation. The degree of pain, redness, flare and cells in the anterior chamber and intraocular pressure were recorded on the day after surgery. The three groups were analysed with respect to change in pupil size, intraocular pressure and degree of inflammation.

RESULTS

The change in pupil size was significantly different among the three groups (p = 0.01), there being a smaller decrease in the treatment groups compared with the placebo group and in the diclofenac treatment group compared with the flurbiprofen treatment group. Significantly less post-operative redness was recorded in the diclofenac treatment group compared with the other groups (p = 0.001). No significant difference was found between the groups as regards anterior chamber cells, flare or intraocular pressure change.

CONCLUSIONS

Pre-operative diclofenac and flurbiprofen drops are effective in maintaining intraoperative mydriasis. Diclofenac reduces post-operative redness on day 1. These effects are of debatable clinical benefit.

Regulation of angiogenesis in vivo by ligation of integrin alpha5beta1 with the central cell-binding domain of fibronectin

Angiogenesis depends on the cooperation of growth factors and cell adhesion events. Although alphav integrins have been shown to play critical roles in angiogenesis, recent studies in alphav-null mice suggest that other adhesion receptors and their ligands also regulate this process. Evidence is now provided that the integrin alpha5beta1 and its ligand fibronectin are coordinately up-regulated on blood vessels in human tumor biopsies and play critical roles in angiogenesis, resulting in tumor growth in vivo. Angiogenesis induced by multiple growth factors in chick embryos was blocked by monoclonal antibodies to the cell-binding domain of fibronectin. Furthermore, application of fibronectin or a proteolytic fragment of fibronectin containing the central cell-binding domain to the chick chorioallantoic membrane enhanced angiogenesis in an integrin alpha5beta1-dependent manner. Importantly, antibody, peptide, and novel nonpeptide antagonists of integrin alpha5beta1 blocked angiogenesis induced by several growth factors but had little effect on angiogenesis induced by vascular endothelial growth factor (VEGF) in both chick embryo and murine models. In fact, these alpha5beta1 antagonists inhibited tumor angiogenesis, thereby causing regression of human tumors in animal models. Thus, fibronectin and integrin alpha5beta1, like integrin alphavbeta3, contribute to an angiogenesis pathway that is distinct from VEGF-mediated angiogenesis, yet important for the growth of tumors.

Endogenous estrogen levels and Alzheimer's disease among postmenopausal women

BACKGROUND

Although several studies have suggested that hormone replacement therapy lowers the risk of AD among postmenopausal women, few studies have evaluated the relationship of endogenous estrogen levels and AD. The current study investigated whether serum estrone and estradiol levels were related to the presence of AD among postmenopausal women not currently taking hormone replacement therapy.

METHODS

Using a case-control design, we examined an ethnically diverse sample of postmenopausal women who met National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for AD (n = 50) and nondemented controls (n = 93). All women were participants in a study of aging and dementia and were seen consecutively between August 1997 and October 1998.

RESULTS

Patients with AD had lower estradiol (F[1,141] = 8.3, p = 0.005) levels than did normal controls. Patients also had lower estrone levels; however, this comparison did not quite meet significance criteria (F[1,141] = 3.6, p = 0.06). Compared to estradiol levels >20 pg/mL, women with AD were four to six times more likely to have levels <20 pg/mL after adjusting for age, years of education, presence of an APOE-epsilon4 allele, ethnicity, and body mass index. There were no significant differences in frequency of AD among women within different quartiles of estrone after adjusting for potential confounds.

CONCLUSIONS

The results of this preliminary case-control study suggest that estradiol levels may decline significantly in women in whom AD develops.

Single nucleotide polymorphisms in the equine transferrin gene

Single nucleotide polymorphisms (SNPs) in exons 13, 15 and 16 of equine transferrin for common, rare and mutant variants were investigated. Compared with previous work a further 13 SNPs have been identified, allowing for the two previously identified clades to be subdivided into 11 groups. A combination of one or more of eight SNPs can be used to classify the equine variants into these 11 groups, since most are co-inherited. Putative sites of glycosylation in exons 13 and 16 showed no polymorphism, suggesting that presence or absence of sugar moieties does not lead to electrophoretic variation between the variants. Using the 26 SNPs currently identified in transferrin it is still not possible to differentiate variants F1 from F2, or D from H2, which represent 75% of the variants occurring in Thoroughbred equine population. This suggests that further SNPs exist in equine transferrin. The significance of the high level of variation in exon 15 is discussed.

Report of the International Equine Gene Mapping Workshop: male linkage map

The goal of the First International Equine Gene Mapping Workshop, held in 1995, was the construction of a low density, male linkage map for the horse. For this purpose, the International Horse Reference Family Panel (IHRFP) was established, consisting of 12 paternal half-sib families with 448 half-sib offspring provided by 10 laboratories. Blood samples were collected and DNA extracted in each laboratory and sent to the Lexington laboratory (KY, USA) for dispatch in aliquots to 14 typing laboratories. In total, 161 markers (144 microsatellites, seven blood groups and 10 proteins) were tested for all families for which the sire was heterozygous. Genealogies and typing data were sent for analysis to the INRA laboratory (Jouy-en-Josas, France) according to a specific format and entered into a database with input verification and output processes. Linkage analysis was performed with the CRIMAP program. Significant linkage was detected for 124 loci, of which 95 were unambiguously ordered using a multipoint analysis with an average spacing of 14.2 CM. These loci were distributed among 29 linkage groups. A more comprehensive analysis including synteny group data and FISH data suggested that 26 autosomes out of 31 are covered. The complete map spans 936 CM.

Plasma amyloid beta-peptide 1-42 and incipient Alzheimer's disease

Mutations in the amyloid precursor protein and presenilin 1 and 2 genes result in elevated plasma levels of the amyloid beta-peptide species terminating at amino acid residue 42 (A beta1-42). In a longitudinal study of unrelated elderly individuals, those who subsequently developed Alzheimer's disease had higher plasma levels of A beta1-42 at entry than did those who remained free of dementia. The results indicate that elevated plasma levels of the released A beta peptide A beta1-42 may be detected several years before the onset of symptoms, supporting that extracellular A beta1-42 plays an important role in the pathogenesis of late-onset Alzheimer's disease.

Functional significance of mild cognitive impairment in elderly patients without a dementia diagnosis

The authors investigated differences in functional ability among three groups of subjects who were not diagnosed with dementia: normal control (NC) subjects (n=35); Clinical Dementia Rating Scale (CDRS) score of 0 (minimal impairment; n=26); and CDRS 0. 5 (questionable dementia; n=42). CDRS 0 and 0. 5 patients reported significantly poorer functioning than NCs in household and other activities, but CDRS 0 and CDRS 0. 5 groups did not differ in self-reported functioning. It is likely that CDRS 0. 5 patients overestimated their functional abilities. Correlations between self- and informant reports of functional status were significantly lower in the CDRS 0. 5 group than in the CDRS 0 group, an important finding for clinical management because patients with questionable dementia may actually be more impaired than they admit. Informants' reports or standardized performance-based assessment should be considered in the clinical evaluation of such patients.

Low-density lipoprotein cholesterol and the risk of dementia with stroke

CONTEXT

Next to Alzheimer disease, vascular dementia is the second most common form of dementia in the elderly, yet few specific risk factors have been identified.

OBJECTIVE

To investigate the relationship of plasma lipids and lipoproteins to dementia with stroke.

DESIGN AND SETTING

Prospective longitudinal community-based study over a 7-year period (1991-1998).

PARTICIPANTS

A total of 1111 nondemented participants (mean [SD] age, 75.0 [5.9] years) were followed up for an average of 2.1 years (range, 1-7.8 years).

MAIN OUTCOME MEASURE

Incident dementia with stroke according to standardized criteria, by baseline levels of total plasma cholesterol and triglycerides, low-density lipoprotein (LDL) cholesterol, LDL levels corrected for lipoprotein(a), high-density lipoprotein cholesterol, lipoprotein(a), and apolipoprotein E genotype.

RESULTS

Two hundred eighty-six (25.7%) of the 1111 subjects developed dementia during follow-up; 61 (21.3%) were classified as having dementia with stroke and 225 (78.7%) as having probable Alzheimer disease. Levels of LDL cholesterol were significantly associated with an increased risk of dementia with stroke. Compared with the lowest quartile, the highest quartile of LDL cholesterol was associated with an approximately 3-fold increase in risk of dementia with stroke, adjusting for vascular risk factors and demographic variables (relative risk [RR], 3.1; 95% confidence interval [CI], 1.5-6.1). Levels of LDL corrected for lipoprotein(a) were an even stronger predictor of dementia with stroke in the adjusted multivariate analysis. Compared with the lowest quartile, the RR of dementia with stroke for the highest quartile of lipoprotein(a)-corrected LDL cholesterol was 4.1 (95% CI, 1.8-9.6) after adjusting for vascular factors and demographic variables. Lipid or lipoprotein levels were not associated with the development of Alzheimer disease in our cohort.

CONCLUSIONS

Elevated levels of LDL cholesterol were associated with the risk of dementia with stroke in elderly patients. Further study is needed to determine whether treatment of elevated LDL cholesterol levels will reduce the risk of dementia with stroke.

Free fatty acid-induced insulin resistance is associated with activation of protein kinase C theta and alterations in the insulin signaling cascade

To examine the mechanism by which free fatty acids (FFAs) induce insulin resistance in vivo, awake chronically catheterized rats underwent a hyperinsulinemic-euglycemic clamp with or without a 5-h preinfusion of lipid/heparin to raise plasma FFA concentrations. Increased plasma FFAs resulted in insulin resistance as reflected by a approximately 35% reduction in the glucose infusion rate (P < 0.05 vs. control). The insulin resistance was associated with a 40-50% reduction in 13C nuclear magnetic resonance (NMR)-determined rates of muscle glycogen synthesis (P < 0.01 vs. control) and muscle glucose oxidation (P < 0.01 vs. control), which in turn could be attributed to a approximately 25% reduction in glucose transport activity as assessed by 2-[1,2-3H]deoxyglucose uptake in vivo (P < 0.05 vs. control). This lipid-induced decrease in insulin-stimulated muscle glucose metabolism was associated with 1) a approximately 50% reduction in insulin-stimulated insulin receptor substrate (IRS)-1-associated phosphatidylinositol (PI) 3-kinase activity (P < 0.05 vs. control), 2) a blunting in insulin-stimulated IRS-1 tyrosine phosphorylation (P < 0.05, lipid-infused versus glycerol-infused), and 3) a four-fold increase in membrane-bound, or active, protein kinase C (PKC) theta (P < 0.05 vs. control). We conclude that acute elevations of plasma FFA levels for 5 h induce skeletal muscle insulin resistance in vivo via a reduction in insulin-stimulated muscle glycogen synthesis and glucose oxidation that can be attributed to reduced glucose transport activity. These changes are associated with abnormalities in the insulin signaling cascade and may be mediated by FFA activation of PKC theta.