Cognitive Performance and Cerebrospinal Fluid Markers in Preclinical Alzheimer's Disease: Results from the Gothenburg H70 Birth Cohort Studies

BACKGROUND: We have previously shown that older adults with preclinical Alzheimer's disease (AD) pathology in cerebrospinal fluid (CSF) had slightly worse performance in Mini-Mental State Examination (MMSE) than participants without preclinical AD pathology. OBJECTIVE: We therefore aimed to compare performance on neurocognitive tests in a population-based sample of 70-year-olds with and without CSF AD pathology. METHODS: The sample was derived from the population-based Gothenburg H70 Birth Cohort Studies in Sweden. Participants (n = 316, 70 years old) underwent comprehensive cognitive examinations, and CSF Aβ-42, Aβ-40, T-tau, and P-tau concentrations were measured. Participants were classified according to the ATN system, and according to their Clinical Dementia Rating (CDR) score. Cognitive performance was examined in the CSF amyloid, tau, and neurodegeneration (ATN) categories. RESULTS: Among participants with CDR 0 (n = 259), those with amyloid (A+) and/or tau pathology (T+, N+) showed similar performance on most cognitive tests compared to participants with A-T-N-. Participants with A-T-N+ performed worse in memory (Supra span (p = 0.003), object Delayed (p = 0.042) and Immediate recall (p = 0.033)). Among participants with CDR 0.5 (n = 57), those with amyloid pathology (A+) scored worse in category fluency (p = 0.003). CONCLUSION: Cognitively normal participants with amyloid and/or tau pathology performed similarly to those without any biomarker evidence of preclinical AD in most cognitive domains, with the exception of slightly poorer memory performance in A-T-N+. Our study suggests that preclinical AD biomarkers are altered before cognitive decline

Cerebrospinal fluid biomarkers of axonal and synaptic degeneration in a population-based sample

Background: Neurofilament light (NfL) and neurogranin (Ng) are promising candidate AD biomarkers, reflecting axonal and synaptic damage, respectively. Since there is a need to understand the synaptic and axonal damage in preclinical Alzheimer’s disease (AD), we aimed to determine the cerebrospinal fluid (CSF) levels of NfL and Ng in cognitively unimpaired elderly from the Gothenburg H70 Birth Cohort Studies classified according to the amyloid/tau/neurodegeneration (A/T/N) system. Methods: The sample consisted of 258 cognitively unimpaired older adults (age 70, 129 women and 129 men) from the Gothenburg Birth Cohort Studies. We compared CSF NfL and Ng concentrations in A/T/N groups using Student’s T-test and ANCOVA. Results: CSF NfL concentration was higher in the A−T−N+ group (p=0.001) and the A−T+N+ group (p=0.006) compared with A−T−N−. CSF Ng concentration was higher in the A−T−N+, A−T+N+, A+T−N+, and A+T+N+ groups (p<0.0001) compared with A−T−N−. We found no difference in NfL or Ng concentration in A+ compared with A− (disregarding T− and N− status), whereas those with N+ had higher concentrations of NfL and Ng compared with N− (p<0.0001) (disregarding A− and T− status). Conclusions: CSF NfL and Ng concentrations are increased in cognitively normal older adults with biomarker evidence of tau pathology and neurodegeneration

Interactions between dietary patterns and genetic factors in relation to incident dementia among 70-year-olds

PURPOSE: To investigate potential interactions between dietary patterns and genetic factors modulating risk for Alzheimer's disease (AD) in relation to incident dementia. METHODS: Data were derived from the population-based Gothenburg H70 Birth Cohort Studies in Sweden, including 602 dementia-free 70-year-olds (examined 1992-93, or 2000-02; 64% women) followed for incident dementia until 2016. Two factors from a reduced rank regression analysis were translated into dietary patterns, one healthy (e.g., vegetables, fruit, and fish) and one western (e.g., red meat, refined cereals, and full-fat dairy products). Genetic risk was determined by APOE ε4 status and non-APOE AD-polygenic risk scores (AD-PRSs). Gene-diet interactions in relation to incident dementia were analysed with Cox regression models. The interaction p value threshold was < 0.1. RESULTS: There were interactions between the dietary patterns and APOE ε4 status in relation to incident dementia (interaction p value threshold of < 0.1), while no evidence of interactions were found between the dietary patterns and the AD-PRSs. Those with higher adherence to a healthy dietary pattern had a reduced risk of dementia among ε4 non-carriers (HR: 0.77; 95% CI: 0.61; 0.98), but not among ε4 carriers (HR: 0.86; CI: 0.63; 1.18). Those with a higher adherence to the western dietary pattern had an increased risk of dementia among ε4 carriers (HR: 1.37; 95% CI: 1.05; 1.78), while no association was observed among ε4 non-carriers (HR: 0.99; CI: 0.81; 1.21). CONCLUSIONS: The results of this study suggest that there is an interplay between dietary patterns and APOE ε4 status in relation to incident dementia

Subtle Differences in Cognition in 70-Year-Olds with Elevated Cerebrospinal Fluid Neurofilament Light and Neurogranin: A H70 Cross-Sectional Study

BACKGROUND: Most research on cerebrospinal fluid (CSF) neurofilament light protein (NfL) as a marker for neurodegeneration and neurogranin (Ng) for synaptic dysfunction has largely focused on clinical cohorts rather than population-based samples. OBJECTIVE: We hypothesized that increased CSF levels of NfL and Ng are associated with subtle cognitive deficits in cognitively unimpaired (CU) older adults. METHODS: The sample was derived from the Gothenburg H70 Birth Cohort Studies and comprised 258 CU 70-year-olds, with a Clinical Dementia Rating score of zero. All participants underwent extensive cognitive testing. CSF levels of NfL and Ng, as well as amyloid β1 - 42, total tau, and phosphorylated tau, were measured. RESULTS: Participants with high CSF NfL performed worse in one memory-based test (Immediate recall, p = 0.013) and a language test (FAS, p = 0.016). Individuals with high CSF Ng performed worse on the memory-based test Supra Span (p = 0.035). When stratified according to CSF tau and Aβ42 concentrations, participants with high NfL and increased tau performed worse on a memory test than participants normal tau concentrations (Delayed recall, p = 0.003). In participants with high NfL, those with pathologic Aβ42 concentrations performed worse on the Delayed recall memory (p = 0.044). In the high Ng group, participants with pathological Aβ42 concentrations had lower MMSE scores (p = 0.027). However, in regression analysis we found no linear correlations between CSF NfL or CSF Ng in relation to cognitive tests when controlled for important co-variates. CONCLUSION: Markers of neurodegeneration and synaptic pathology might be associated with subtle signs of cognitive decline in a population-based sample of 70-year-olds

Polygenic risk scores for Alzheimer's disease are related to dementia risk in APOE ɛ4 negatives

Introduction: Studies examining the effect of polygenic risk scores (PRS) for Alzheimer's disease (AD) and apolipoprotein E (APOE) genotype on incident dementia in very old individuals are lacking. / Methods: A population‐based sample of 2052 individuals ages 70 to 111, from Sweden, was followed in relation to dementia. AD‐PRSs including 39, 57, 1333, and 13,942 single nucleotide polymorphisms (SNPs) were used. / Results: AD‐PRSs (including 39 or 57 SNPs) were associated with dementia (57‐SNPs AD‐PRS: hazard ratio 1.09, confidence interval 1.01–1.19, P = .03), particularly in APOE ɛ4 non‐carriers (57‐SNPs AD‐PRS: 1.15, 1.05–1.27, P = 4 × 10–3, 39‐SNPs AD‐PRS: 1.22, 1.10–1.35, P = 2 × 10–4). No association was found with the other AD‐PRSs. Further, APOE ɛ4 was associated with increased risk of dementia (1.60, 1.35–1.92, P = 1 × 10–7). In those aged ≥95 years, the results were similar for the AD‐PRSs, while APOE ɛ4 only predicted dementia in the low‐risk tertile of AD‐PRSs. / Discussion: These results provide information to identify individuals at increased risk of dementia

Prevalence of preclinical Alzheimer disease: Comparison of current classification systems

OBJECTIVE: To determine the prevalence of preclinical Alzheimer disease (AD) according to current classification systems by examining CSF from a representative general population sample of 70-year-olds from Gothenburg, Sweden. METHOD: The sample was derived from the population-based H70 Gothenburg Birth Cohort Studies in Gothenburg, Sweden. The participants (n = 322, age 70 years) underwent comprehensive neuropsychiatric, cognitive, and somatic examinations. CSF levels of β-amyloid (Aβ)42, Aβ40, total tau, and phosphorylated tau were measured. Preclinical AD was classified according to criteria of the A/T/N system, Dubois 2016, National Institute on Aging-Alzheimer's Association (NIA-AA) criteria, and International Working Group-2 (IWG-2) criteria. Individuals with Clinical Dementia Rating score >0 were excluded, leaving 259 cognitively unimpaired individuals. RESULTS: The prevalence of amyloid pathology was 22.8%, of total tau pathology was 33.2%, and of phosphorylated tau pathology was 6.9%. With the A/T/N system, the prevalence of A+/T-/N- was 13.1%, A+/T-/N+ was 7.3%, A+/T+/N+ was 2.3%, A-/T-/N+ was 18.9%, and A-/T+/N+ was 4.6%. When the Dubois criteria were applied, the prevalence of asymptomatic at risk for AD was 36.7% and of preclinical AD was 9.7%. With the NIA-AA criteria, the prevalence of stage 1 was 13.1% and stage 2 was 9.7%. With the IWG-2 criteria, the prevalence of asymptomatic at risk for AD was 9.7%. The APOE ε4 allele was associated with several of the categories. Men more often had total tau pathology, A+/T-/N+, preclinical AD according to Dubois 2016, asymptomatic at risk for AD according to the IWG-2 criteria, and NIA-AA stage 2. CONCLUSION: The prevalence of pathologic AD markers was very common (46%) in a representative population sample of 70-year-olds. The clinical implications of these findings need to be scrutinized further in longitudinal studies

Personality Traits in Miners with Past Occupational Elemental Mercury Exposure

In this study, we evaluated the impact of long-term occupational exposure to elemental mercury vapor (Hg(0)) on the personality traits of ex-mercury miners. Study groups included 53 ex-miners previously exposed to Hg(0) and 53 age-matched controls. Miners and controls completed the self-reporting Eysenck Personality Questionnaire and the Emotional States Questionnaire. The relationship between the indices of past occupational exposure and the observed personality traits was evaluated using Pearson’s correlation coefficient and on a subgroup level by machine learning methods (regression trees). The ex-mercury miners were intermittently exposed to Hg(0) for a period of 7–31 years. The means of exposure-cycle urine mercury (U-Hg) concentrations ranged from 20 to 120 μg/L. The results obtained indicate that ex-miners tend to be more introverted and sincere, more depressive, more rigid in expressing their emotions and are likely to have more negative self-concepts than controls, but no correlations were found with the indices of past occupational exposure. Despite certain limitations, results obtained by the regression tree suggest that higher alcohol consumption per se and long-term intermittent, moderate exposure to Hg(0) (exposure cycle mean U-Hg concentrations > 38.7 < 53.5 μg/L) in interaction with alcohol remain a plausible explanation for the depression associated with negative self-concept found in subgroups of ex-mercury miners. This could be one of the reason for the higher risk of suicide among miners of the Idrija Mercury Mine in the last 45 years

Twin study shows association between monocyte chemoattractant protein-1 and kynurenic acid in cerebrospinal fluid

Preclinical studies indicate a link between the kynurenine pathway and monocyte chemoattractant protein-1 (MCP-1), but there is a lack of clinical studies examining this further. We here perform a secondary analysis of kynurenine metabolites and MCP-1 in cerebrospinal fuid of 23 twins afected from schizophrenia, bipolar disorder or unafected. We show an association between MCP-1 and kynurenic acid (KYNA), driven by unique environmental infuences and a less pronounced association between MCP-1 and tryptophan. No association was detected between MCP-1 and quinolinic acid. Further studies on the mechanism behind the putative relationship between KYNA and MCP-1 are needed