The Mediterranean diet: a historical perspective.

The Mediterranean diet, which was born in the Mediterranean basin, was initially quite poor and simple, essentially based on the products that grew almost spontaneously along the shores of the Mediterranean, i.e., olives, grapes, and wheat, which were long cultivated in the Mediterranean region. The invasions of the Roman Empire by barbarian populations, between 400 and 800 AD, made the diet enriched with products from wild uncultivated areas, meat from game and pigs, and vegetables. With the arrival of the Arabs in southern Italy in the ninth century, the focus of the diet shifted to carbohydrates, particularly to dried pasta and to other new ingredients. The Arabs primarily brought a new imaginative spirit to the kitchen by introducing and using an infinity of condiments and seasonings. The discovery of the Americas and the arrival of new ingredients from the New World brought the final adjustments to the Mediterranean diet: new meat (turkey), new vegetables (potatoes, broad beans, corn, tomatoes,) new fruits (strawberries, pineapples, coconuts, peanuts), chocolate, coffee and sugar completed the list of components of the Mediterranean diet as we know it today.

Vascular effects of the Mediterranean diet-part II: role of omega-3 fatty acids and olive oil polyphenols.

The lower occurrence of cardiovascular disease and cancer in populations around the Mediterranean basin as detected in the 1950s was correctly attributed to the peculiar dietary habits of those populations. Essentially, until the mid-20th century, typical Mediterranean diets were rich in fruits, vegetables, legumes, whole-wheat bread, nuts, fish, and, as a common culinary trait, the routine use of extra-virgin olive oil. Nowadays, the regular adoption of such dietary patterns is still thought to result in healthful benefits. Such patterns ensure the assumption of molecules with antioxidant and anti-inflammatory actions, among which ω-3 polyunsaturated fatty acids (PUFAs), ω-9 monounsaturated fatty acids (oleic acid), and phenolic compounds. The aim of this review is to provide an update of the vasculo-protective pathways mediated by ω-3 PUFAs and polyphenols in the context of the modern Mediterranean dietary habits, including the possible cross-talk and synergy between these typical components. This review complements a parallel one focusing on the role of dietary nitrates and alimentary fats.

Vascular factors predict polyneuropathy in a non-diabetic elderly population.

We prospectively examined whether vascular factors are related to an increased incidence of Chronic Idiopathic Distal Symmetric Neuropathy (CI-DSN) in a non-diabetic elderly population. In 8 Italian municipalities, 2,512 men and women without both diabetes and CI-DSN at baseline are examined. Potential effect of vascular factors was estimated by regressing new onset CI-DSN on the occurrence of several vascular diseases and risk factors. Multivariate relative risks of CI-DSN were estimated by Cox proportional hazards models. After 3.8 (±2.4) years of follow-up, we documented 51 incident CI-DSN cases. At univariate analysis, age, comorbidity, waist circumference, leg length, peripheral artery disease, and coronary heart disease proved to increase the risk of developing CI-DSN. By multivariate analyses, only age (RR = 1.08; 95 % CI, 1.02-1.14), leg length (RR = 1.05; 95 % CI, 1.01-1.1) and peripheral artery disease (RR = 2.75; 95 % CI, 1.15-6.56) proved significant predictors of CI-DSN. Separate analyses by gender show that age is an independent predictor of CI-DSN both in men and in women, while PAD predicts the disease only in men, together with body height. Incidence of CI-DSN is higher in individuals carrying vascular conditions. In men, the presence at baseline of peripheral artery disease is associated with a threefold increase in the risk of developing CI-DSN. The incidence of neuropathy in non-diabetic individuals is associated with potentially modifiable vascular factors.

From excess adiposity to insulin resistance: the role of free fatty acids.

With a positive caloric balance, adipocytes undergo excessive hypertrophy, which causes adipocyte dysfunction, as well as adipose tissue endocrine and immune responses. A preferential site of fat accumulation is the abdominal-perivisceral region, due to peculiar factors of the adipose tissue in such sites, namely an excess of glucocorticoid activity, which promotes the accumulation of fat; and the greater metabolic activity and sensitivity to lipolysis, due to increased number and activity of ß3-adrenoceptors and, partly, to reduced activity of α2-adrenoceptors. As a consequence, more free fatty acids (FFA) are released into the portal system. Hypertrophic adipocytes begin to secrete low levels of TNF-α, which stimulate preadipocytes and endothelial cells to produce MCP-1, in turn responsible for attracting macrophages to the adipose tissue, thus developing a state of chronic low-grade inflammation which is causally linked to insulin resistance. Excess of circulating FFA, TNF-α and other factors induces insulin resistance. FFA cause insulin resistance by inhibiting insulin signaling through the activation of serin-kinases, i.e. protein kinase C-Θ, and the kinases JNK and IKK, which promote a mechanism of serine phosphorylation of Insulin Receptor Substrates (IRS), leading to interruption of the downstream insulin receptor (IR) signaling. TNF-α, secreted by hypertrophic adipocytes and adipose tissue macrophages, also inhibits IR signaling by a double mechanism of serine-phosphorylation and tyrosine-dephosphorylation of IRS-1, causing inactivation and degradation of IRS-1 and a consequent stop of IR signaling. Such mechanisms explain the transition from excess adiposity to insulin resistance, key to the further development of type 2 diabetes.

Metabolic syndrome, mild cognitive impairment, and progression to dementia. The Italian Longitudinal Study on Aging.

We investigated the relationship of metabolic syndrome (MetS) and its individual components with incidence of mild cognitive impairment (MCI) and its progression to dementia in a large longitudinal Italian population-based sample with a 3.5-year follow-up. A total of 2097 participants from a sample of 5632 65-84-year-old subjects from the Italian Longitudinal Study on Aging were evaluated. MetS was defined according to the Third Adults Treatment Panel of the National Cholesterol Education Program criteria. MCI, dementia, Alzheimer's disease (AD), and vascular dementia (VaD) were classified using current published criteria. Among MCI patients those with MetS (N=49) had a higher risk of progression to dementia (HR, 4.40; 95% CI, 1.30-14.82) compared with those without MetS (N=72). After a multivariate adjustment, the risk in MCI patients with MetS approximately doubled (multivariate adjusted HR, 7.80, 95% CI 1.29-47.20) compared with those MCI without MetS. Finally, among non-cognitively impaired individuals there were no significant differences in risks of developing MCI in those who were affected by MetS (N=608) in comparison with those without MetS (N=837), as well as excluding those individuals with undernutrition or low inflammatory status with or without undernutrition. In our population, among MCI patients the presence of MetS independently predicted an increased risk of progression to dementia over 3.5 years of follow-up.

Prevalence of aging-associated cognitive decline in an Italian elderly population: results from cross-sectional phase of Italian PRoject on Epidemiology of Alzheimer's disease (IPREA).

BACKGROUND AND AIMS: The prevalence of the preclinical phase of dementia varies greatly, according to the diagnostic criteria and assessment procedures applied. The purpose of this study was to estimate the prevalence of cognitive impairment according to the Aging-Associated Cognitive Decline (AACD) diagnostic criteria in an Italian elderly population. METHODS: In a multicenter community-based prospective study, 4785 Italian subjects aged 65-84 years, randomly selected from the registries of 12 Italian municipalities, were assessed by personal and informant interviews, physical and neurological examinations and an extensive neuropsychological battery. RESULTS: Of these older subjects, 274 (9.2%) fulfilled all the AACD criteria, whereas 561 (18.8%) fulfilled only 3 of them (AACD-3). When the two groups diagnosed according to AACD criteria (AACD and AACD- 3) were merged, the prevalence was 28.0% (28.3% for men, 27.6% for women). Two other groups of subjects were also identified: a) Subjects with Objective evidence of Cognitive Decline without cognitive complaints (OCD), 508 (17.0%), i.e., subjects with documented neuropsychological deficits, although neither subjects nor informants reported cognitive complaints; and b) Subjects with Cognitive Complaints without objective demonstrable cognitive deficits (CC), 44 (1.5%), i.e., subjects and/or informants reported cognitive complaints without evidence of neuropsychological deficits. Thus, taking into account the additional OCD group, a total of 1343 persons with cognitive impairment without dementia (45.0%) was identified. CONCLUSIONS: On the basis of our results, we estimate that 45% of our population-based Italian sample aged 65-84 years had some kind of cognitive deficits without dementia.

Aluminum in the diet and Alzheimer's disease: from current epidemiology to possible disease-modifying treatment.

In recent years, interest in the potential role of metals in the pathogenesis of Alzheimer's disease (AD) has grown considerably. In particular, aluminum (Al) neurotoxicity was suggested after its discovery in the senile plaques and neurofibrillary tangles that represent the principal neuropathological hallmarks of AD. Al is omnipresent in everyday life and can enter the human body from several sources, most notably from drinking water and food consumption. The evidence supporting association from ingestion of Al from drinking water is somewhat stronger than for its ingestion from food. However, other elements present in drinking water, such as fluoride, copper, zinc, or iron could also have an effect on cognitive impairment or modify any Al neurotoxicity. Some epidemiological studies, but not all, suggested that silica could be protective against Al damage, because it reduces oral absorption of Al and/or enhances Al excretion. Some epidemiological investigations suggested an association between chronic exposure to Al and risk of AD, although this relationship falls short of all the criteria generally attributed to causation. Future studies need to be more rigorous to truly test the validity of previous findings and in doing so attempt to identify dose-response relationships between Al and AD risk which may provide new routes to disease-modifying treatment of AD or possibly some lifestyle modification, to supplement existing symptomatic approaches.

Late-life depression, mild cognitive impairment, and dementia: possible continuum?

Clinical and epidemiologic research has focused on the identification of risk factors that may be modified in predementia syndromes, at a preclinical and early clinical stage of dementing disorders, with specific attention to the role of depression. Our goal was to provide an overview of these studies and more specifically to describe the prevalence and incidence of depression in individuals with mild cognitive impairment (MCI), the possible impact of depressive symptoms on incident MCI, or its progression to dementia and the possible mechanisms behind the observed associations. Prevalence and incidence of depressive symptoms or syndromes in MCI vary as a result of different diagnostic criteria and different sampling and assessment procedures. The prevalence of depression in individuals with MCI was higher in hospital-based studies (median: 44.3%, range: 9%-83%) than in population-based studies (median: 15.7%, range: 3%-63%), reflecting different referral patterns and selection criteria. Incidence of depressive symptoms varied from 11.7 to 26.6/100 person-years in hospital-based and population-based studies. For depressed normal subjects and depressed patients with MCI, the findings on increased risk of incident MCI or its progression to dementia were conflicting. These contrasting findings suggested that the length of the follow-up period, the study design, the sample population, and methodological differences may be central for detecting an association between baseline depression and subsequent development of MCI or its progression to dementia. Assuming that MCI may be the earliest identifiable clinical stage of dementia, depressive symptoms may be an early manifestation rather than a risk factor for dementia and Alzheimer disease, arguing that the underlying neuropathological condition that causes MCI or dementia also causes depressive symptoms. In this scenario, at least in certain subsets of elderly patients, late-life depression, MCI, and dementia could represent a possible clinical continuum.

Metabolic syndrome and the risk of vascular dementia: the Italian Longitudinal Study on Ageing.

OBJECTIVE: The authors investigated the relationship of metabolic syndrome (MetS) and its individual components with incident dementia in a prospective population-based study with a 3.5-year follow-up. METHODS: A total of 2097 participants from a sample of 5632 subjects (65-84 years old) from the Italian Longitudinal Study on Ageing were evaluated. MetS was defined according to the Third Adults Treatment Panel of the National Cholesterol Education Program criteria. Dementia, Alzheimer disease (AD) and vascular dementia (VaD) were classified using current published criteria. RESULTS: MetS subjects (N=918) compared with those without MetS (N=1179) had an increased risk for VaD (1.63% vs 0.85%, adjusted hazard ratio (HR) 3.71, 95% CI 1.40 to 9.83). After excluding 338 subjects with baseline undernutrition, MetS subjects compared with those without MetS had an elevated risk of VaD (adjusted HR, 3.82; 95% CI 1.32 to 11.06). Moreover, those with MetS and high inflammation had a still further higher risk of VaD (multivariate adjusted HR, 9.55; 95% CI 1.17 to 78.17) compared with those without MetS and high inflammation. On the other hand, those with MetS and low inflammation compared with those without MetS and low inflammation did not exhibit a significant increased risk of VaD (adjusted HR, 3.31, 95% CI 0.91 to 12.14). Finally, a synergistic MetS effect versus its individual component effects was verified on the risk of VaD. CONCLUSION: In our population, MetS subjects had an elevated risk of VaD that increased after excluding patients with baseline undernutrition and selecting MetS subjects with high inflammation.

Interleukin 6-174 G/C promoter and variable number of tandem repeats (VNTR) gene polymorphisms in sporadic Alzheimer's disease.

BACKGROUND: Previous studies examining the association between the interleukin 6 (IL-6)-174 C/G polymorphism and Alzheimer's disease (AD) have yielded conflicting results. Furthermore, the C allele of the IL-6 variable number of tandem repeats (VNTR) polymorphism was associated with a delayed onset and a decreased risk of AD. METHODS: A total sample of 149 AD patients, and 298 age- and sex-matched unrelated caregivers from Apulia, southern Italy, were genotyped for the apolipoprotein E (APOE) polymorphism, the VNTR polymorphism in the 3' flanking region, and the -174G/C single-nucleotide polymorphism (SNP) in the promoter region of IL-6 gene on chromosome 7. Furthermore, we performed a haplotype analysis on these two polymorphisms on IL-6 locus. RESULTS: IL-6 VNTR and -174G/C allele and genotype frequencies were similar between AD patients and controls, also after stratification for late-onset (> or =65 years) and early-onset (<65 years) or APOE epsilon4 status. Furthermore, there was no evidence of linkage disequilibrium between the VNTR and -174G/C polymorphisms, not supporting a previous reported additive effect of both IL-6 polymorphisms on AD risk. CONCLUSIONS: Our findings did not support a role of IL-6-174 G/C and IL-6 VNTR polymorphisms in the risk of sporadic AD in southern Italy, suggesting that these polymorphisms of IL-6 gene were at most weak genetic determinants of AD.

Dietary fatty acids in dementia and predementia syndromes: epidemiological evidence and possible underlying mechanisms.

Drugs currently used in the treatment of cognitive impairment and dementia have a very limited therapeutic value, suggesting the necessity to potentially individualize new strategies able to prevent and to slow down the progression of predementia and dementia syndromes. An increasing body of epidemiological evidence suggested that elevated saturated fatty acids (SFA) could have negative effects on age-related cognitive decline (ARCD) and mild cognitive impairment (MCI). Furthermore, a clear reduction of risk for cognitive decline has been found in population samples with elevated fish consumption, high intake of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), particularly n-3 PUFA. Epidemiological findings demonstrated that high PUFA intake appeared to have borderline non-significant trend for a protective effect against the development of MCI. Several hypotheses could explain the association between dietary unsaturated fatty acids and cognitive functioning, including mechanisms through the co-presence of antioxidant compounds in food groups rich in fatty acids, via atherosclerosis and thrombosis, inflammation, accumulation of b-amyloid, or via an effect in maintaining the structural integrity of neuronal membranes, determining the fluidity of synaptosomal membranes that thereby regulate neuronal transmission. However, recent findings from clinical trials with n-3 PUFA supplementation showed efficacy on depressive symptoms only in non-apolipoprotein E (APOE) epsilon4 carriers, and on cognitive symptoms only in very mild Alzheimer's disease (AD) subgroups, MCI patients, and cognitively unimpaired subjects non-APOE epsilon4 carriers. These data together with epidemiological evidence support a possible role of fatty acid intake in maintaining adequate cognitive functioning and possibly for the prevention and management of cognitive decline and dementia, but not when the AD process has already taken over.

All-cause mortality and competing risks of fatal and nonfatal vascular events in the Italian longitudinal study on aging: impact of lipoprotein(a).

Among possible determinants of vascular events, the role of high lipoprotein(a) (Lp[a]) serum levels represents a still uncertain independent risk factor in elderly populations. Moreover, the cumulative incidence of nonfatal vascular events due to high Lp(a) serum levels is conditioned by the competing risk of death from any causes that are a function of age. After a 6.3-year median follow up, we tested the competing risks of all-cause mortality, cumulative fatal-nonfatal stroke events, cumulative fatal-nonfatal coronary artery disease (CAD) events, and nonfatal stroke or CAD events due to high Lp(a) serum levels in a population-based, prospective study conducted in one of the eight centers of the Italian Longitudinal Study on Aging (ILSA), Casamassima, Bari, Italy. Of 704 elderly individuals (65-84 years), 372 (169 women and 203 men) agreed to participate in the study. As compared with those in the lowest Lp(a) tertile serum levels, subjects in the highest tertile (>20 mg/dL) had a higher partially adjusted risk of nonfatal CAD (hazard ratio, 4.19; 95% confidence interval [CI], 1.36-12.94) and nonfatal stroke (hazard ratio, 3.38; 95% CI, 1.00-11.56). Compared with those in the lowest tertile, subjects in the highest tertile had a higher fully adjusted risk of nonfatal CAD (hazard ratio, 3.41; 95% CI, 1.08-10.78). Finally, overall no statistically significant association was found between Lp(a) and the risk of all-cause mortality, cumulative fatal-nonfatal stroke, and cumulative fatal-nonfatal CAD events. In our population, Lp(a) was not a significant independent predictor of stroke and death from all causes, but it was an independent predictor of nonfatal CAD. Finally competing risk, conditioning the timing and occurrence of vascular events in our study population, could be a correct approach for evaluating the role of Lp(a) lipoprotein in vascular disease among elderly people.

Disease-modifying approach to the treatment of Alzheimer's disease: from alpha-secretase activators to gamma-secretase inhibitors and modulators.

In the last decade, advances in understanding the neurobiology of Alzheimer's disease (AD) have translated into an increase in clinical trials assessing various potential AD treatments. At present, drugs used for the treatment of AD only slightly delay the inevitable symptomatic progression of the disease and do not affect the main neuropathological hallmarks of the disease, i.e. senile plaques and neurofibrillary tangles. Brain accumulation of oligomeric species of beta-amyloid (A beta) peptides, the principal components of senile plaques, is believed to play a crucial role in the development of AD. Based on this hypothesis, huge efforts are being made to identify drugs able to interfere with proteases regulating A beta formation from amyloid precursor protein (APP). Compounds that stimulate alpha-secretase, the enzyme responsible for non-amyloidogenic metabolism of APP, are being developed and one of these, EHT-0202, has recently commenced evaluation in a phase II study. The discovery of inhibitors of beta-secretase (memapsin-2, beta-amyloid cleaving enzyme-1 [BACE-1]), the enzyme that regulates the first step of amyloidogenic APP metabolism, has proved to be particularly difficult because of inherent medicinal chemistry issues and only one compound (CTS-21166) has proceeded to clinical testing. Conversely, several compounds that inhibit gamma-secretase, the pivotal enzyme that generates A beta, have been identified, the most advanced being LY-450139 (semagacestat), presently in phase III clinical development. There has been considerable disappointment over the failure of a phase III study of tarenflurbil, a compound believed to modulate the activity of gamma-secretase, after encouraging phase II findings. Nevertheless, other promising gamma-secretase modulators are being developed and are approaching clinical testing. All these therapeutic approaches increase the hope of slowing the rate of decline in patients with AD and modifying the natural history of this devastating disease within the next 5 years.

Dietary fatty acids and predementia syndromes.

An increasing body of epidemiological evidence suggests that elevated saturated fatty acids (SFA) could have negative effects on age-related cognitive decline (ARCD). Furthermore, a reduction of risk for cognitive decline and mild cognitive impairment (MCI) has been found in population samples with elevated fish consumption, and high intake of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), particularly n-3 PUFA. However, recent findings from clinical trials with n-3 PUFA supplementation showed efficacy on depressive symptoms in non-apolipoprotein E (APOE) epsilon4 carriers, and on cognitive symptoms only in very mild Alzheimer's disease (AD) subgroups, MCI patients, and cognitively unimpaired non-APOE epsilon4 carriers. These data, together with epidemiological evidence, support the idea that n-3 PUFA may play a role in maintaining adequate cognitive functioning in predementia syndromes, but not when the AD process has already taken over. Therefore, at present, no definitive dietary recommendations on fish and unsaturated fatty acids consumption, or lower intake of saturated fat, in relation to the risk for dementia and cognitive decline are possible.