RESUMEN

Introduction: Depressive symptoms are associated with Alzheimer's disease (AD), but their neurobiological and neuropsychological correlates remain poorly understood. We investigate if depressive symptoms are associated with amyloid (Aß) pathology and cognition in predementia AD. Methods: We included subjective cognitive decline (SCD, n = 160) and mild cognitive impairment (MCI, n = 192) from the dementia disease initiation cohort. Depressive symptoms were assessed using the Geriatric Depression Scale (GDS-15). Aß pathology was determined using cerebrospinal fluid (CSF) Aß42/40 ratio. Associations between depressive symptoms and cognition were assessed with logistic regression. Results: Only the Aß negative MCI group (MCI-Aß-) was associated with depressive symptoms (odds ratio [OR] = 2.65, p = 0.005). Depressive symptoms were associated with worse memory in MCI-Aß- (OR = 0.94, p = 0.039), but with better performance in MCI-Aß+ (OR = 1.103, p = 0.001). Conclusion: Our results suggest that depressive symptoms in MCI are neither associated with Aß pathology, nor AD-associated memory impairment. However, memory impairment in non-AD MCI may relate to depressive symptoms.

RESUMEN

Semantic verbal fluency is among the most employed tasks in cognitive aging research and substantial work is devoted to understanding the underlying mechanisms behind age-related differences at the neural and behavioral levels. The present investigation aimed to evaluate the role of moderating variables, such as age, sex, MMSE, and proxies of cognitive reserve (CR) on the hemodynamic response evoked by semantic verbal fluency in healthy young and healthy older adults. So far, no study has been conducted to this end. To elucidate the exclusive effect of the mentioned variables on brain activation during semantic fluency, finger tapping was included as a control task. Results showed that disregarding adjustments for age, older adults displayed important parietal activations during semantic fluency as well as during finger-tapping. Specifically, the anterior intra-parietal sulcus (IPS) and left inferior parietal lobule (IPL) were areas activated in both tasks in the older group. Younger adults, only displayed parietal activations related to age and sex when these demographics were employed as predictors. Concerning proxies of CR in semantic fluency, the only vocabulary was an important moderator in both age groups. Higher vocabulary scores were associated with lesser activation in occipital areas. Education did not show significant correlations with brain activity during semantic fluency in any of the groups. However, both CR proxies were significantly correlated to brain activations of older adults during finger tapping. Specifically, vocabulary was associated with frontal regions, while education correlated with parietal lobe and cingulate gyrus. Finally, the effects of MMSE were mostly observed on brain activation of older adults in both tasks. These findings demonstrate that the effects of moderating variables on shaping brain activation are intricate and not exclusive of complex verbal tasks. Thus, before adjusting for "nuisance variables," their importance needs to be established. This is especially true for samples including older adults for whom a motor task may be a demanding operation due to normal age-related processes of dedifferentiation.

RESUMEN

BACKGROUND: Subjective cognitive decline (SCD) is associated with an increased risk of Alzheimer's disease (AD). However, patients reporting SCD to their general practitioner are not always referred to a memory clinic. OBJECTIVE: To investigate whether prior history of medical help-seeking is associated with AD biomarker abnormality, worse cognitive performance, and/or depressive symptoms in SCD. METHODS: We compared levels of cerebrospinal fluid (CSF) Aß1 - 42, cognitive performance, and depressive symptoms (15-item Geriatric Depression Scale, GDS-15) between healthy controls (n = 88), SCD with a history of medical help seeking (SCD-HS, n = 67), and SCD non help-seekers (SCD-NHS, n = 44). Cases with evidence of amyloid plaques (CSF Aß1 - 42 ≤708 ng/l) and symptoms of depression (GDS-15≥6) were determined in both SCD groups. RESULTS: The SCD-HS group had lower CSF Aß1 - 42 (p < 0.01), lower word list learning and memory recall (p < 0.0001), and an increased level of depressive symptoms (p < 0.0001) compared to controls and SCD-NHS cases. The SCD-HS group had more cases with symptoms of depression (n = 12, 18%) and amyloid plaques (n = 18, 27%) compared to SCD-NHS (n = 1, 2% and n = 7, 16%, respectively). None of the SCD-HS cases and only one SCD-NHS case had concurrent symptoms of depression and amyloid plaques. The SCD-HS cases showed equal word list learning and memory performance regardless of amyloid status or symptoms of depression. CONCLUSION: Medical help-seeking in SCD is associated with an increased risk of AD pathology or symptoms of depression. However, subtle memory deficits are seen in SCD help-seekers, also without amyloid plaques or symptoms of depression.

Asunto(s)

RESUMEN

Background/Objective: In recent years, several slightly younger cohorts have been established in order to study the preclinical and prodromal phases of dementia. The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) wordlist memory test (WLT) is widely used in dementia research. However, culturally adapted and demographically adjusted test norms for younger ages are lacking.Method: This paper investigates effects of age, gender and years of education on test performance and offers demographically adjusted norms for the CERAD WLT using a regression-based norming procedure for the age span 40-80 years based on healthy controls (n = 227) from the Norwegian "Dementia Disease Initiation" (DDI) (n = 168) and "Trønderbrain" (n = 59) cohorts. In order to evaluate normative performance, we apply the norms to an independent sample of persons diagnosed with mild cognitive impairment (MCI = 168) and perform multiple regression analyses to evaluate adjustment of pertinent demographics.Results: CERAD WLT norms adjusted for effects of age, gender and educational level are proposed. The norms successfully adjusted for effects of age, gender and education in an independent sample of Norwegians with MCI.Conclusion: Demographically adjusted norms for the CERAD WLT for ages 40-80 years based on a Norwegian sample are proposed. To our knowledge, this is the first normative study of this test to offer demographically adjusted norms for this age span.

Asunto(s)

RESUMEN

BACKGROUND: Cognitive assessment is essential in tracking disease progression in AD. Presently, cohorts including preclinical at-risk participants are recruited by different means, which may bias cognitive and clinical features. We compared recruitment strategies to levels of cognitive functioning. OBJECTIVE: We investigate recruitment source biases in self-referred and memory clinic-referred patient cohorts to reveal potential differences in cognitive performance and demographics among at-risk participants. METHODS: We included 431 participants 40-80 years old. Participants were classified as controls (n = 132) or symptom group (n = 299). The symptom group comprised of subjective cognitive decline (SCD, n = 163) and mild cognitive impairment (MCI, n = 136). We compared cognitive performance and demographics in memory clinic-referrals (n = 86) to self-referred participants responding to advertisements and news bulletins (n = 179). Participants recruited by other means were excluded from analysis (n = 34). RESULTS: At symptom group level, we found significant reductions in cognitive performance in memory clinic-referrals compared to self-referrals. However, here reductions were only found within the MCI group. We found no differences in cognitive performance due to recruitment within the SCD group. The MCI group was significantly impaired compared to controls on all measures. Significant reductions in learning, and executive functions were also found for the SCD group. CONCLUSION: Regardless of recruitment method, both the SCD and MCI groups showed reductions in cognitive performance compared to controls. We found differences in cognitive impairment for memory clinic-referrals compared to self-referrals only within the MCI group, SCD-cases being equally affected irrespective of referral type.

Asunto(s)

RESUMEN

While APOEɛ4 is the major genetic risk factor for Alzheimer's disease (AD), amyloid dysmetabolism is an initial or early event predicting clinical disease and is an important focus for secondary intervention trials. To improve identification of cases with increased AD risk, we evaluated recruitment procedures using pathological CSF concentrations of Aß42 (pAß) and APOEɛ4 as risk markers in a multi-center study in Norway. In total, 490 subjects aged 40-80 y were included after response to advertisements and media coverage or memory clinics referrals. Controls (n = 164) were classified as normal controls without first-degree relatives with dementia (NC), normal controls with first-degree relatives with dementia (NCFD), or controls scoring below norms on cognitive screening. Patients (n = 301) were classified as subjective cognitive decline or mild cognitive impairment. Subjects underwent a clinical and cognitive examination and MRI according to standardized protocols. Core biomarkers in CSF from 411 and APOE genotype from 445 subjects were obtained. Cases (both self-referrals (n = 180) and memory clinics referrals (n = 87)) had increased fractions of pAß and APOEɛ4 frequency compared to NC. Also, NCFD had higher APOEɛ4 frequencies without increased fraction of pAß compared to NC, and cases recruited from memory clinics had higher fractions of pAß and APOEɛ4 frequency than self-referred. This study shows that memory clinic referrals are pAß enriched, whereas self-referred and NCFD cases more frequently are pAß negative but at risk (APOEɛ4 positive), suitable for primary intervention.

Asunto(s)