Measures are needed that identify persons that will develop Alzheimer's disease in order to target them for preventative interventions. There is evidence from animal, pathological and imaging studies that disruption of white matter occurs in the course of Alzheimer's disease and may be an early event. Prior studies have suggested that late-myelinating regions or white matter connecting limbic structures are particularly susceptible to degradation. Persons destined to develop the disease by virtue of fully penetrant genetic alterations (familial Alzheimer's disease or FAD) provide a model in which early and even presymptomatic changes of the disease may be identified. In this study we performed diffusion tensor imaging (DTI) on 2 demented and 21 subjects at-risk for inheriting an FAD mutation. We compared global and localized fractional anisotropy (FA) measures in white matter between FAD mutation carriers and non-carriers in the preclinical (clinical dementia rating <1, n = 20) and presymptomatic (clinical dementia rating = 0, n = 15) stages of the disease. There were no significant differences between mutation carriers and non-carriers with regard to absolute age, age relative to the typical age of disease diagnosis in their family, gender or Mini-Mental Status Examination Score. Among preclinical FAD mutation carriers (n = 12), mean whole brain white-matter FA (P = 0.045), FA of the columns of the fornix (P = 0.012), area of the perforant pathways bilaterally (right side: P = 0.028, left side: P = 0.027) and left orbitofrontal lobe (P = 0.024) were decreased relative to that of non-carriers (n = 8). We also found that FA in the columns of the fornix (P = 0.008) and left orbitofrontal lobe white matter (P = 0.045) were decreased in the eight presymptomatic mutation carriers compared to seven non-carriers. Logistic regression demonstrated that FA of the columns of the fornix was a better predictor of mutation status than was cross-sectional area of the fornix, global mean white-matter FA and left frontal lobe white-matter FA. In a linear regression analysis, white-matter volume (P = 0.002), hippocampal volume (P = 0.023) and mutation status (P = 0.032) significantly predicted fornix FA. We conclude that FA is decreased in the white matter in preclinical and even presymptomatic FAD mutation carriers, particularly in the late-myelinating tracts connecting limbic structures. Decreased FA in of the columns of the fornix is particularly robust in early FAD and may provide a biomarker for early disease in sporadic Alzheimer's disease.

Background: Persons at risk for familial Alzheimer disease (FAD) provide a model in which biomarkers can be studied in presymptomatic disease. Methods: Twenty-one subjects at risk for presenilin-1 (n = 17) or amyloid precursor protein (n = 4) mutations underwent evaluation with the Clinical Dementia Rating (CDR) scale. We obtained plasma from all subjects and CSF from 11. Plasma (Aβ₄₀, Aβ₄₂, F₂-isoprostanes) and CSF (F₂-isoprostanes, t-tau, p-tau₁₈₁, Aβ₄₀, Aβ₄₂, and Aβ₄₂/Aβ₄₀ ratio) levels were compared between FAD mutation carriers (MCs) and noncarriers (NCs). Results: Plasma Aβ₄₂ levels (25.1 pM vs 15.5 pM, p = 0.031) and the ratio of Aβ₄₂/Aβ₄₀ (0.16 vs 0.11, p = 0.045) were higher in presymptomatic MCs. Among MCs, those with CDR scores of 0.5 had lower plasma Aβ₄₂ levels than those with CDR scores of 0 (14.1 pM vs 25.1, p = 0.02). The ratio of Aβ₄₂ to Aβ₄₀ was also reduced in the CSF (0.08 vs 0.15, p = 0.046) of nondemented MCs compared to NCs. Total CSF tau and p-tau₁₈₁ levels were elevated in presymptomatic FAD MCs. CSF levels of F₂-isoprostanes were also elevated in MCs (n = 7, 48.6 pg/mL) compared to NCs (n = 4, 21.6 pg/mL, p = 0.031). Conclusions: Our data indicate that Aβ₄₂ is elevated in plasma in familial Alzheimer disease (FAD) mutation carriers (MCs) and suggests that this level may decrease with disease progression prior to the development of overt dementia. We also demonstrated that the ratio of Aβ₄₂ to Aβ₄₀ was reduced in the CSF of nondemented MCs and that elevations of t-tau and p-tau₁₈₁ are sensitive indicators of presymptomatic disease. Our finding of elevated F₂-isoprostane levels in the CSF of preclinical FAD MCs suggests that oxidative stress occurs downstream to mismetabolism of amyloid precursor protein.

To define changes in cortical function in persons inheriting familial Alzheimer disease (FAD) mutations before the onset of cognitive decline. Twenty-six subjects with a family history of FAD were divided into 2 subgroups according to genotype (FAD mutation carriers, n = 15; FAD noncarriers, n = 11). Subjects were given standardized tests of cognitive function and the Clinical Dementia Rating scale (CDR). Sensory (P50, N100, P200) and cognitive (N200, P300) event-related potentials were recorded during an auditory discrimination task. Amplitudes and latencies of cortical potentials were compared among FAD mutation carriers and noncarriers. FAD mutation carriers and noncarriers did not significantly differ in age or on measures of cognitive function, but FAD carriers had a greater incidence of 0.5 CDR scores (1/10 noncarriers, 5/15 carriers). Relative to noncarriers, FAD mutation carriers had significantly longer latencies of the N100, P200, N200, and P300 components, and smaller slow wave amplitudes. Subanalyses of subjects having CDR scores of 0.0 also showed latency increases in FAD mutation carriers. Auditory sensory and cognitive cortical potentials in persons with familial Alzheimer disease (FAD) mutations are abnormal approximately 10 years before dementia will be manifest. Longer event-related potential latencies suggest slowing of cortical information processing in FAD mutation carriers.

Nine families with autosomal dominant Alzheimer’s disease (AD), all of whom had the Ala431Glu substitution in the PSEN1 gene and came from Jalisco State in Mexico, have been previously reported. As they shared highly polymorphic flanking dinucleotide marker alleles, this strongly suggests that this mutation arose from a common founder. In the current letter, we expand this observation by describing an additional 15 independent families with the Ala431Glu substitution in the PSEN1 gene and conclude that this mutation is not an uncommon cause of early-onset autosomal dominant AD in persons of Mexican origin.

Background Mutations in the presenilin (PSEN1, PSEN2) and amyloid precursor protein (APP) genes cause familial Alzheimer's disease (FAD) in a nearly fully penetrant, autosomal dominant manner, providing a unique opportunity to study presymptomatic individuals who can be predicted to develop Alzheimer's disease (AD) with essentially 100% certainty. Using tensor-based morphometry (TBM), we examined brain volume differences between presymptomatic and symptomatic FAD mutation carriers and non-carrier (NC) relatives. Methods Twenty-five mutation carriers and 10 NC relatives underwent brain MRI and clinical assessment. Four mutation carriers had dementia (MUT-Dem), 12 had amnestic mild cognitive impairment (MUT-aMCI) and nine were cognitively normal (MUT-Norm). TBM brain volume maps of MUT-Norm, MUT-aMCI and MUT-Dem subjects were compared to NC subjects. Results MUT-Norm subjects exhibited significantly smaller volumes in the thalamus, caudate and putamen. MUT-aMCI subjects had smaller volumes in the thalamus, splenium and pons, but not in the caudate or putamen. MUT-Dem subjects demonstrated smaller volumes in temporal, parietal and left frontal regions. As non-demented carriers approached the expected age of dementia diagnosis, this was associated with larger ventricular and caudate volumes and a trend towards smaller temporal lobe volume. Conclusions Cognitively intact FAD mutation carriers had lower thalamic, caudate and putamen volumes, and we found preliminary evidence for increasing caudate size during the predementia stage. These regions may be affected earliest during prodromal stages of FAD, while cortical atrophy may occur in later stages, when carriers show cognitive deficits. Further studies of this population will help us understand the progression of neurobiological changes in AD.

The Houston Conference Guidelines (Hannay et al., 1998) provided an initial framework for North American neuropsychology training that served the specialty well for several decades. Subsequent advances in technology, increased diversity of the U.S. and Canadian populations, and the adoption of competency-based training models within Health Service Psychology have created a need to update neuropsychology training guidelines. Therefore, in 2022, the Minnesota Conference to Update Education and Training Guidelines in Clinical Neuropsychology began a two-year drafting process leading to the currently proposed update. A Steering Committee worked with content experts, consultants, and delegates representing North American neuropsychological organizations and specialists. The final version of the guidelines was developed after reviewing neuropsychological training literature, gathering feedback from specialists, and making iterative revisions of earlier drafts to reach consensus. The resulting "Minnesota Guidelines" include five foundational (Neuroscience and Brain Behavior Relationships; Integration of Science and Practice; Ethics, Standards, Laws, and Policies; Diversity; and Professional Relationships) and eight functional (Assessment; Intervention; Interdisciplinary Systems and Consultation; Research and Scholarship; Technology and Innovation; Teaching, Supervision, and Mentoring; Health and Professional Advocacy; and Administration, Management, and Business) areas of competency required for entry level specialty practice. While consensus was not achieved, a majority of voting delegates recommended the Guidelines for adoption and the Guidelines have been endorsed by six neuropsychology education and board certification organizations. The American Academy of Clinical Neuropsychology has not endorsed the Minnesota Guidelines and will not make an endorsement decision until three months after online publication.