Clinical impact of microbleeds in patients with Alzheimer's disease.

INTRODUCTION: Cerebral microbleeds (CMBs) are more frequent in patients with Alzheimer's disease (AD) than in the general population. However, their clinical significance remains poorly understood. We carried out a multimodal approach to evaluate the impact of CMBs at a clinical, neuropsychological, and survival level, as well as on core AD biomarkers in the cerebrospinal fluid (CSF) in AD patients. METHODS: We prospectively recruited 98 patients with mild-moderate AD. At baseline, they underwent brain MRI, and AD CSF biomarkers and APOE genotypes were analysed. An extensive neuropsychological battery was performed at baseline and after 1 year of follow-up. We analysed the stroke incidence and mortality with survival analyses. RESULTS: Forty-eight (48.5%) patients had at least one CMBs. Eight (8.2%) patients had strictly nonlobar CMBs, 39 (40.2%) had any lobar CMB locations. The incidence of stroke was higher in AD patients with lobar CMBs than in those without CMBs (p < 0.05). Mortality did not differ among groups (p > 0.05). At the cognitive level, CMBs patients deteriorated more rapidly at 12 months according to MMSE scores, with no differences observed at 24 months. We did not observe differences in the other tests, except for an increase in caregiver burden in the CMBs group. The presence of cerebral amyloidosis and APOE ε4 were associated with a greater presence of CMBs. CONCLUSION: CMBs are associated with an increased risk of ischemic stroke in AD patients without differences in mortality. Patients with CMBs did not seem to have different consequences associated with cognitive decline except for an increase in caregiver overload.

The circadian rest-activity pattern predicts cognitive decline among mild-moderate Alzheimer's disease patients.

BACKGROUND: Alterations in circadian rhythms are present in the presymptomatic stage of Alzheimer's disease (AD), possibly contributing to its pathogenesis. However, it is unknown whether such alterations are associated with worse outcomes once individuals are diagnosed with symptomatic disease. We aimed to evaluate the association between the circadian rest-activity pattern and AD-related features in patients with mild-moderate AD. METHODS: We assessed the circadian rest-activity pattern of consecutive patients with mild-moderate AD through actigraphy for 14 days. Cerebrospinal fluid was obtained to determine the levels of important pathological markers including amyloid-beta protein (Aß42), phosphorylated tau (P-tau), total tau (T-tau), and neurofilament light (NF-L). Neuropsychological evaluation was conducted at the beginning of the study and after 12 months of follow-up. Linear regression models were performed considering the global population and Aß42+ patients only. RESULTS: The cohort included 100 patients with mild-moderate AD. The median age [p25;p75] was 76.0 [73.0;80.0] years and 63.0% were female. Older age (effect size [SE] of 0.324 [0.096]; p = 0.001) and male sex (0.780 [0.193]; p = 0.001) were associated with increased fragmentation and decreased synchronization of the rhythm, respectively. After adjusting for age, sex, and season of the year, increased levels of T-tau (effect size [95% CI] of 0.343 [0.139 to 0.547]; p = 0.001) and NF-L (0.444 [0.212 to 0.676]; p = 0.001) were associated with a higher amplitude of the rest-activity rhythm. Increased fragmentation of the rhythm at baseline was associated with greater cognitive decline after one year of follow-up independent of age, sex, T-tau/Aß42 ratio, educational level, and season of the year (- 0.715 [- 1.272 to - 0.157]; p = 0.013). Similar findings were obtained considering only the Aß42+ patients. CONCLUSIONS: Our results suggest a potential role of the circadian rest-activity pattern in predicting the cognitive decline of patients with mild-moderate AD. Further studies are warranted to confirm these findings and to elucidate whether there is causality among the observed associations.

Sleep profile predicts the cognitive decline of mild-moderate Alzheimer's disease patients.

STUDY OBJECTIVES: To investigate the association between sleep and cognitive decline of patients with mild-moderate Alzheimer's disease. METHODS: Observational, prospective study, including consecutive patients diagnosed with mild-moderate Alzheimer's disease. Cerebrospinal fluid was collected for amyloid-beta, total-tau, and phospho-tau levels determination. Also, overnight polysomnography was performed, followed by neuropsychological evaluations at baseline and after 12 months of follow-up. Principal component analysis revealed two profiles of patients in terms of sleep: one with a propensity to deepen the sleep (deep sleepers) and the other with a propensity to spend most of the time in the lighter sleep stage (light sleepers). RESULTS: The cohort included 125 patients with a median [IQR] of 75.0 [72.0;80.0] years. Deep and light sleepers did not present differences in relation to the cerebrospinal fluid pathological markers and to the cognitive function at the baseline. However, there was a significant difference of -1.51 (95% CI: -2.43 to -0.59) in the Mini-mental state examination after 12 months of follow-up. Accordingly, sleep depth and cognitive decline presented a dose-response relationship (p-for-trend = 0.02). Similar outcomes were observed in relation to the processing speed (Stroop words test, p-value = 0.016) and to the executive function (Verbal fluency test, p-value = 0.023). CONCLUSIONS: Considering the increased cognitive decline presented by light sleepers, the sleep profile may have a predictive role in relation to the cognitive function of patients with mild-moderate Alzheimer's disease. The modifiable nature of sleep sets this behavior as a possible useful intervention to prevent a marked cognitive decline. CLINICAL TRIAL INFORMATION: Role of Hypoxia Ans Sleep Fragmentation in Alzheimer's Disease. and Sleep Fragmentation. Completed. NCT02814045.

Decrease in sleep depth is associated with higher cerebrospinal fluid neurofilament light levels in patients with Alzheimer's disease.

STUDY OBJECTIVES: The majority of studies investigating the association between sleep and Alzheimer's disease (AD) biomarkers have been performed in healthy participants. Our objective was to investigate the association between sleep and several biomarkers that reflect distinct aspects of AD physiopathology. METHODS: The cohort included 104 individuals with mild-moderate AD. The participants were submitted to one-night polysomnography, and cerebrospinal fluid was collected in the following morning to measure the selected biomarkers associated with amyloid deposition, tau pathology, neurodegeneration, axonal damage, synaptic integrity, neuroinflammation, and oxidative damage. RESULTS: There was a positive correlation between neurofilament light (NF-L) and the time spent in stage 1 of non-rapid eyes movement (NREM) (N1) sleep and a negative correlation between this marker and the time spent in stage 3 of NREM (N3) sleep. Accordingly, we observed that deep sleep was associated with lower levels of NF-L, whereas light sleep increased the probability of having higher levels of this marker. Furthermore, chitinase-3-like-1 (YKL-40) was negatively correlated with sleep efficiency, the time spent in stage 2 of NREM (N2) sleep, and the time spent in N3 sleep. Conversely, there was a positive correlation between N3 sleep and the oxidative protein damage markers N-ε-(carboxyethyl)lysine and N-ε-(malondialdehyde)lysine. CONCLUSIONS: There were significant correlations between sleep parameters and AD biomarkers related to axonal damage and neuroinflammation, such as NF-L and YKL-40. A lack of deep sleep was associated with higher levels of NF-L. This highlights a potential role for NF-L as a biomarker of sleep disruption in patients with mild-moderate AD in addition to its role in predicting neurodegeneration and cognitive decline.

Obstructive sleep apnoea and cognitive decline in mild-to-moderate Alzheimer's disease.

We evaluated the influence of untreated obstructive sleep apnoea (OSA) on the magnitude of cognitive decline and on several cognitive subdomains in patients with mild-to-moderate Alzheimer's disease.In this single-centre study, 144 patients were recruited prospectively from a cognitive impairment unit and underwent overnight polysomnography.The mean±sd change in the Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-cog) score at 12 months was 3.19±5.61 in the non-OSA group and 0.08±5.62 in the OSA group, with an intergroup difference of -3.36 (95% CI 0.19-0.16; p=0.002). We did not observe a significant difference in any cognitive subdomains at 12 months. Regarding Mini-Mental State Examination scores at 36 months, the mean change was 1.69 (95% CI -1.26-4.64; p=0.445). No significant differences were found among different OSA severity groups.We observed that ADAS-cog scores were better in the OSA group than in the non-OSA group by a statistically but not clinically significant margin. We did not find differences in the different cognitive subdomains after 1 year or in global cognition after 3 years of follow-up.

Prevalence of obstructive sleep apnea in Alzheimer's disease patients.

OBJECTIVE: To assess the prevalence of obstructive sleep apnea (OSA) in patients with mild-moderate Alzheimer's Disease (AD) and to evaluate cognitive characteristics according to the severity of OSA. METHODS: Patients with mild-moderate AD, recruited prospectively from a cognitive impairment unit, underwent overnight polysomnography. OSA was defined as an apnea-hypopnea index > 5/h. AD severity was assessed using the Mini-Mental State Examination and extensive neuropsychological battery. Epworth Sleepiness Scale and APOE status were analyzed. RESULTS: The cohort included 128 patients with a median [IQR] age of 75.0 [72.0;79.2] years and 57.8% were women. OSA was diagnosed in 116 subjects (90.6%). The distribution of mild, moderate and severe severity of OSA was 29 (22.7%), 37 (28.9%) and 50 (39.1%), respectively. Regarding sleep symptoms, the cohort showed normal values of daytime sleepiness (median EES score 5 [3, 8]), while nycturia (89.1%) and snoring (71.1%) were the most common symptoms. Participants with severe OSA included a higher proportion of older men, were associated with snoring and sedentariness. No significant differences in cognitive assessment were found between patients with and without severe OSA in any of the domains. The prevalence of APOE ε4 was not significantly different between patients with and without severe OSA. CONCLUSION: There was a high prevalence of OSA in patients with mild-moderate AD. OSA was not associated with sleepiness or worse cognitive function. APOE ε4 was not related to the presence or severity of OSA. Further longitudinal studies will be required to evaluate whether OSA impairs cognitive evolution in AD patients.

The STOP-Bang and Berlin questionnaires to identify obstructive sleep apnoea in Alzheimer's disease patients.

BACKGROUND: A close relationship between obstructive sleep apnoea (OSA) and Alzheimer's disease (AD) has been described in recent years. OSA is a risk factor for AD, but the diagnosis and clinical characteristics of OSA in patients with AD is not well understood. This study evaluated the clinical utility of two screening questionnaires, the STOP-Bang questionnaire (SBQ) and the Berlin questionnaire (BQ), to identify which patients with mild AD are at higher risk of having OSA and to determine the clinical predictors of OSA in this population. METHODS: In this study, 91 consecutive outpatients with mild AD were prospectively evaluated with the SBQ and the BQ. All patients underwent level 1 in-laboratory polysomnography. The predictive performance of the questionnaires were calculated for different apnoea-hypopnoea index (AHI) cut-offs. RESULTS: The median age of the patients was 76.0 (73.0; 80.0) years, and 58 (63.7%) were female. Of those, 81 patients (89.02%) were found to have OSA defined by an AHI > 5 events/h. Comparing the predictive performances of the SBQ and the BQ, the SBQ was found to have a higher diagnostic sensitivity (85% vs 4%), a lower specificity (35% vs. 96%), a higher positive predictive value (PPV) (44% vs 33%) and negative predictive value (NPV) (80% vs 65%) for detecting severe OSA at an AHI cut-off of 30 events/h. None of the items alone in the two questionnaires predicted the risk of OSA. A modified version of the SBQ, with new cut-off points for several variables according to the characteristics of AD patients, showed a slightly greater AUC than the standard SBQ (AUC 0.61 vs 0.72). CONCLUSION: There is a high prevalence of OSA among patients with mild AD. The SBQ and the BQ are not good screening tools for detecting OSA in patients with AD. A modified version of SBQ could increase the detection of these patients.

Minor Hallucinations in Alzheimer's Disease.

BACKGROUND: Hallucinations may have a broad spectrum and include so-called minor hallucinations (MHs). MHs include passage hallucinations (PHs), visual illusions, and presence hallucinations (PrHs). OBJECTIVE: To determine the prevalence and characteristics of MHs in Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) patients, and to describe their potential relationship with cognition, behavioral symptoms, and use of psychoactive drugs. METHODS: We have recruited prospectively and consecutively 268 subjects (90 AD mild-moderate drug-naïve patients, 78 aMCI, and 100 controls). All patients responded to a semi-structured questionnaire in order to rate psychotic phenomena. Clinical, neuropsychological, and demographic data of patients with and without MH were compared with those of age, sex, and education-matched controls. RESULTS: The prevalence of MHs was 21.1% (19) in AD, 12.8% (10) in aMCI, and 3% (3) in controls (p < 0.01). The most frequent MH was PrH (9.3%), followed by PH (4.9%) and illusion (0.7%). Eight (27.8%) patients had more than one MH. After adjusting for age and gender, there was a negative correlation between the presence of MHs and MMSE score (r = -0.261; p < 0.01) and a positive correlation between MHs and Neuropsychiatric Inventory score (r = 0.237; p < 0.01). We did not observe a significant relationship between presence of MHs and the consumption of psychoactive drugs (p > 0.05). CONCLUSION: We have shown that the presence of MHs in patients with newly diagnosed, untreated AD and aMCI is more than controls. MHs were correlated with other behavioral symptoms and a worse cognitive performance. We suggest the specific interrogation for MHs as a clinical feature for this population.