Lipid Metabolism in Late-Onset Alzheimer's Disease Differs from Patients Presenting with Other Dementia Phenotypes.

Abnormal cerebrospinal fluid (CSF) levels of ß-amyloid peptides (Aß42) and Tau and cognitive decline are typical characteristics of Alzheimer's disease (AD). Since dysregulation in lipid metabolism accompanies abnormal amyloid formation, we quantified glycerophospholipids (GP) and sphingolipids (SP) in CSF fractions from participants with late-onset AD (LOAD, n = 29) or with Other Dementia (OD, n = 10) to determine if alterations in lipid metabolism account for pathological differences. Aß42 and total Tau levels were determined using a sandwich ELISA. Liposomal-based fluorescent assays were used to measure phospholipase A2 (PLA2) and acid or neutral sphingomyelinase (aSMase, nSMase) activities. Supernatant fluid (SF) and nanoparticle (NP) lipids were quantified using LC-MS/MS. Although CSF Aß42 and Tau levels are similar, phosphatidylserine (PS) in SF and ceramide (CM) levels in NP are significantly higher in OD compared with LOAD. The aSMase but not the nSMase activity is higher in OD. PLA2 activity in CSF from OD subjects positively correlates with several GP classes in SF and NP fractions but not in LOAD fractions. Our data indicate differences in CSF lipid metabolism between dementia variants. Higher levels of inflammatory and apoptotic lipids may induce faster neuronal death, resulting in the earlier cognitive decline in patients with OD phenotypes.

Alzheimer's disease and late-onset epilepsy of unknown origin: two faces of beta amyloid pathology.

Although amyloid pathology plays a role in epilepsy, little is known about the relationship between beta amyloid and progression to Alzheimer's disease (AD) among patients with late-onset epilepsy of unknown origin (LOEU). This multicenter, observational, prospective study enrolled 40 consecutive nondemented adults diagnosed with LOEU, together with 43 age- and sex-matched healthy controls. All patients completed neuropsychological tests, core CSF AD biomarkers assessment (Aß1-42, total tau, and phosphorylated tau), and follow-up for a mean of 3 years to verify cognitive decline. Despite age and baseline cognitive performance were similar to healthy controls, patients with LOEU had significant prevalence of CSF pathological Aß1-42 (<500 pg/mL; 37.5%), 7.5% displaying an AD-like CSF pattern. Moreover, 17.5% of patients with LOEU converted to AD dementia, versus none among healthy controls (p < 0.005). Patients with LOEU with pathological Aß1-42 had a hazard ratio 3.4 (CI 0.665-17.73) for progression to AD dementia at follow-up. Patients with LOEU have a high prevalence of abnormal CSF Aß1-42 and progression to AD dementia compared with healthy controls, and therefore should be monitored for cognitive decline.

Nonlesional late-onset epilepsy: Semiology, EEG, cerebrospinal fluid, and seizure outcome characteristics.

INTRODUCTION: Incidence and prevalence of epilepsy increase with advancing age. Although the majority of late-onset epilepsies are of lesional origin, a considerable proportion of patients present with unknown etiology. The aim of this study was to evaluate the semiological, electroencephalographic (EEG), and cerebrospinal fluid (CSF) characteristics as well as the 12-month seizure outcome in a cohort of patients with nonlesional late-onset epilepsy (≥55 years). METHOD: A total of 54 patients with newly diagnosed nonlesional late-onset epilepsy (NLLOE) were retrospectively evaluated for seizure type using the most recent International League Against Epilepsy (ILAE) classification of seizure types, EEG characteristics, and CSF profile and followed-up for at least 12 months after epilepsy onset. Results were compared with a gender-matched control group of 58 patients with nonlesional early-onset epilepsy (NLEOE). RESULTS: The predominant seizure types in NLLOE were focal to bilateral tonic-clonic seizures (30%) as well as focal onset impaired awareness motor seizures (IAMS) (22%) and focal onset impaired awareness nonmotor seizures (IANMS) (22%). The predominant seizure types in NLEOE were focal to bilateral tonic-clonic seizures (43%) as well as focal onset aware nonmotor seizures (ANMS) (31%) and IAMS (31%). Focal onset impaired awareness nonmotor seizures were found to be more characteristic in patients with NLLOE (p = 0.019; α < 0.05; NLLOE: 22.2% vs. NLEOE: 8.6%). Electroencephalography revealed no significant differences between groups. Of interest, three patients with NLLOE (8%) presented with oligoclonal bands (OCB) in CSF albeit absence of antineuronal antibodies. Seizure-free rate was 70%. Adverse effects from medication leading to antiepileptic drug (AED) change were reported in 12 patients (22%), valproate was the best tolerated AED in patients with NLLOE [adverse effects in 9%, compared with 12% (gabapentin) and 26% (levetiracetam)]. CONCLUSIONS: Using the most recent classification system, different patterns of semiological characteristics were identified: NLLOE more frequently present with IANMS, whereas patients with NLEOE rather have ANMS. Oligoclonal bands were only detected in patients with NLLOE, indicating that careful exclusion of autoimmune encephalitis in this patient group is warranted. Our findings may help to more accurately identify and characterize patients with NLLOE to improve targeted diagnostics and adequate treatment in this challenging group of patients.

Amyloid Hypothesis: Is There a Role for Antiamyloid Treatment in Late-Life Depression?

Antidepressants have modest efficacy in late-life depression (LLD), perhaps because various neurobiologic processes compromise frontolimbic networks required for antidepressant response. We propose that amyloid accumulation is an etiologic factor for frontolimbic compromise that predisposes to depression and increases treatment resistance in a subgroup of older adults. In patients without history of depression, amyloid accumulation during the preclinical phase of Alzheimer disease (AD) may result in the prodromal depression syndrome that precedes cognitive impairment. In patients with early-onset depression, pathophysiologic changes during recurrent episodes may promote amyloid accumulation, further compromise neurocircuitry required for antidepressant response, and increase treatment resistance during successive depressive episodes. The findings that support the amyloid hypothesis of LLD are (1) Depression is a risk factor, a prodrome, and a common behavioral manifestation of AD; (2) amyloid deposition occurs during a long predementia period when depression is prevalent; (3) patients with lifetime history of depression have significant amyloid accumulation in brain regions related to mood regulation; and (4) amyloid deposition leads to neurobiologic processes, including vascular damage, neurodegeneration, neuroinflammation, and disrupted functional connectivity, that impair networks implicated in depression. The amyloid hypothesis of LLD is timely because availability of ligands allows in vivo assessment of amyloid in the human brain, a number of antiamyloid agents are relatively safe, and there is evidence that some antidepressants may reduce amyloid production. A model of LLD introducing the role of amyloid may guide the design of studies aiming to identify novel antidepressant approaches and prevention strategies of AD.

Cerebrospinal fluid biomarkers for neuropsychological symptoms in early stage of late-onset Alzheimer's disease.

PURPOSE: In addition to testing blood, cerebrospinal fluid (CSF) has been analyzed in the search for biomarkers. The aim of this study was to identify biomarkers in CSF for neuropsychological symptoms in early-stage late-onset Alzheimer's disease (LOAD). METHODS: CSF levels of beta-amyloid 1-42 (Aß42), F2-isoprostanes (F2-IsoPs) and F4-neuroprostanes (F4-NPs) were assayed in nine patients with mild Alzheimer's disease (AD), nine patients with amnestic mild cognitive impairment (a-MCI) and nine individuals with normal mental function. The three groups underwent neuropsychological testing. RESULTS: CSF levels of F2-IsoPs and F4-NPs did not significantly differ among the three groups. Aß42 in CSF was significantly higher in the control group compared with the mild AD group (p < 0.001) and a-MCI group (p = 0.03). There was a significant positive correlation between the level of F2-IsoPs and Aß42 in the a-MCI group and between the level of F2-IsoPs and F4-NPs in the mild AD group. In comparisons between the mild AD group and a-MCI group combined, the cognitive impairment (CI) group, with the control group, the median levels of F2-IsoPs and F4-NPs were significantly higher in the CI group and median level of Aß42 was significantly lower in the CI group. Both the levels of F2-IsoPs and Aß42 were significantly negatively correlated with paranoid and delusional ideation and total score for the Behavioral Pathology in Alzheimer's Disease Scale (BEHAVE-AD). CONCLUSIONS: The findings suggest CSF levels of Aß42 and F2-IsoPs are associated with the severity of neuropsychological symptoms.