amyloid-beta-peptides and Brain-Diseases

The diagnosis of idiopathic normal pressure hydrocephalus (iNPH) is sometimes complicated by concomitant Alzheimer's disease (AD) pathology. The purpose of the present study is to identify an iNPH-specific cerebrospinal fluid (CSF) biomarker dynamics and to assess its ability to differentiate iNPH from AD. Total tau (t-tau), tau phosphorylated at threonine 181 (p-tau), amyloid-β (Aβ) 42 and 40, and leucine-rich α-2-glycoprotein (LRG) were measured in 93 consecutive CSF samples consisting of 55 iNPH (46 tap test responders), 20 AD, 11 corticobasal syndrome, and 7 spinocerebeller disease. Levels of t-tau and p-tau were significantly decreased in iNPH patients especially in tap test responders compared to AD. Correlation was observed between Mini-Mental State Examination scores and Aβ42 in AD (R = 0.44) and mildly in iNPH (R = 0.28). Although Aβ42/40 ratio showed no significant difference between iNPH and AD (p = 0.08), the levels of Aβ40 and Aβ42 correlated positively with each other in iNPH (R = 0.73) but much less in AD (R = 0.26), suggesting that they have discrete amyloid clearance and pathology. LRG levels did not differ between the two. Thus, our study shows that although CSF biomarkers of iNPH patients can be affected by concomitant tau and/or amyloid pathology, CSF t-tau and p-tau are highly useful for differentiation of iNPH and AD.

Topics: Aged; Aged, 80 and over; alpha-Macroglobulins; Alzheimer Disease; Amyloid beta-Peptides; Analysis of Variance; Area Under Curve; Biomarkers; Brain Diseases; Chi-Square Distribution; Female; Humans; Hydrocephalus, Normal Pressure; Male; Middle Aged; Peptide Fragments; Retrospective Studies; tau Proteins

Transgenic mice expressing mutant forms of both amyloid-beta (Abeta) precursor protein (APP) and presenilin (PS) 2 develop severe brain amyloidosis and cognitive deficits, two pathological hallmarks of Alzheimer's disease (AD). One-year-old APP/PS2 mice with high brain levels of Abeta and abundant Abeta plaques show disturbances in spatial learning and memory. Treatment of these deteriorated mice with a systemic slow-release formulation of insulin-like growth factor I (IGF-I) significantly ameliorated AD-like disturbances. Thus, IGF-I enhanced cognitive performance, decreased brain Abeta load, increased the levels of synaptic proteins, and reduced astrogliosis associated to Abeta plaques. The beneficial effects of IGF-I were associated to a significant increase in brain Abeta complexed to protein carriers such as albumin, apolipoprotein J or transthyretin. Since levels of APP were not modified after IGF-I therapy, and in vitro data showed that IGF-I increases the transport of Abeta/carrier protein complexes through the choroid plexus barrier, it seems that IGF-I favors elimination of Abeta from the brain, supporting a therapeutic use of this growth factor in AD.

Topics: Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Amyloidosis; Analysis of Variance; Animals; Behavior, Animal; Blood-Brain Barrier; Brain Chemistry; Brain Diseases; Cognition Disorders; Disease Models, Animal; Immunohistochemistry; Insulin-Like Growth Factor I; Maze Learning; Mice; Mice, Inbred C57BL; Mice, Transgenic; Peptide Fragments; Spatial Behavior

Severe cognitive impairment is common in elderly patients with schizophrenia. Alzheimer's disease is the main cause of dementia among the elderly. Biochemical and genetic studies suggest that amyloid beta-peptide is central in Alzheimer's disease. The authors examined the possible involvement of amyloid beta-peptide in cognitive impairment in schizophrenia.. Specific antibodies against two major forms of amyloid beta-peptide, Abetax-40 and Abetax-42, were used in sandwich enzyme-linked immunosorbent assays to determine the levels of amyloid beta-peptide in postmortem brain samples from Alzheimer's disease patients (N=10), normal elderly comparison subjects (N=11), and schizophrenia patients with (N=7) or without (N=26) Alzheimer's disease.. The levels of amyloid beta-peptide were highest in the Alzheimer's disease patients, followed by the patients with schizophrenia and comparison subjects. The mean Abetax-42 level in the schizophrenia patients without Alzheimer's disease was similar to that in the comparison subjects, but the level in the schizophrenia patients with Alzheimer's disease was significantly higher than in those without Alzheimer's disease or the comparison subjects. The Abetax-42 level in the schizophrenia patients with Alzheimer's disease was significantly lower than the level in the Alzheimer's disease cohort.. In contrast to elderly schizophrenia patients with Alzheimer's disease pathology, those without Alzheimer's disease had amyloid beta-peptide levels that were not significantly different from those of normal subjects; hence amyloid beta-peptide does not account for the cognitive deficits in this group. These results suggest that the causes of cognitive impairment in "pure" schizophrenia are different from those in Alzheimer's disease.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Amyloidosis; Brain Chemistry; Brain Diseases; Cognition Disorders; Comorbidity; Enzyme-Linked Immunosorbent Assay; Female; Geriatric Assessment; Humans; Male; Peptide Fragments; Plaque, Amyloid; Prefrontal Cortex; Schizophrenia

The incidence, distribution and chemical composition of amyloid-beta (A beta) peptide-positive deposits were investigated in the lower primate species common marmoset (Callithrix jacchus). No A beta deposits were observed in the brains of 7 marmosets below 7 years of age. In 15 marmosets above 7 years, 60% displayed cortical A beta-immunoreactive plaques, 80% had A beta deposited in intracortical vessels and 87% displayed A beta deposits in meningeal vessels. The cerebral cortex of the oldest animal (15 years) contained a substantial density of deposits. A beta-immunoreactive plaques were found predominantly in association cortical zones followed by a lower density in paralimbic cortical areas. Deposits within vessels were most frequent in occipital cortex. A beta40 was found primarily in vascular deposits, while A beta42 was present in plaques. Approximately 20% of plaques and most vascular deposits displayed thioflavin S staining, indicative of the presence of fibrillar A beta. Varying proportions of A beta deposits contained acetylcholinesterase or butyrylcholinesterase activities and apolipoprotein E and alpha1-antichymotrypsin immunoreactivity. A few plaques contained immunoreactivity for amyloid precursor protein in swollen neurites. However, no abnormally phosphorylated tau immunoreactivity was present in these neurites. Survival analysis in a colony of marmosets indicated that only 6% of animals can be expected to survive beyond 7 years of age. These results indicate that the aged marmoset brain displays A beta deposits with a distribution and chemical composition similar to those found in the human. These similarities suggest that the aged marmoset may be a useful lower primate model for the study of the pathological effects of A beta. However, the relatively small number of animals which can be expected to reach old age severely limits the utility of this species as a model of A beta deposition.

Topics: Aging; alpha 1-Antichymotrypsin; Amyloid beta-Peptides; Animals; Apolipoproteins E; Benzothiazoles; Brain Diseases; Callithrix; Cerebral Cortex; Cholinesterases; Disease Models, Animal; Female; Incidence; Male; Neurites; Peptide Fragments; Plaque, Amyloid; Survival Analysis; Thiazoles