Microstate Changes Associated With Alzheimer's Disease in Persons With Down Syndrome.

Down syndrome (DS) is associated with development of dementia due to Alzheimer's disease (AD). However, due to considerable heterogeneity in intellectual function among persons with DS, it is difficult to assess whether a person with DS has developed dementia due to AD (DS-AD). EEG spectral power has previously shown very promising results with increased slowing in DS-AD compared to DS. However, another technique called microstates may be used to assess whole-brain dynamics and has to our knowledge not previously been investigated in either DS or DS-AD. The aim of the current study was to assess whether microstates could be used to differentiate between adults with DS, and DS-AD. We included EEGs from 10 persons with DS and 15 persons with DS-AD in the analysis. For the microstate analyses, we calculated four global maps, which were then back-fitted to all the EEGs. Lastly, we extracted the duration, occurrence, and coverage for each of the microstates. Here, we found the four archetypical maps as has previously been reported in the literature. We did not find any significant difference between DS and DS-AD but the largest difference in microstate duration between DS and DS-AD was found in microstate A and D. These findings are in line with structural MR studies showing that both the frontal and temporal lobes are affected in persons with DS-AD. Microstates may potentially serve as a diagnostic marker, but larger studies are needed to confirm these findings.

Differences in quantitative methods for measuring subjective cognitive decline - results from a prospective memory clinic study.

BACKGROUND: Cognitive complaints occur frequently in elderly people and may be a risk factor for dementia and cognitive decline. Results from studies on subjective cognitive decline are difficult to compare due to variability in assessment methods, and little is known about how different methods influence reports of cognitive decline. METHODS: The Subjective Memory Complaints Scale (SMC) and The Memory Complaint Questionnaire (MAC-Q) were applied in 121 mixed memory clinic patients with mild cognitive symptoms (mean MMSE = 26.8, SD 2.7). The scales were applied independently and raters were blinded to results from the other scale. Scales were not used for diagnostic classification. Cognitive performances and depressive symptoms were also rated. We studied the association between the two measures and investigated the scales' relation to depressive symptoms, age, and cognitive status. RESULTS: SMC and MAC-Q were significantly associated (r = 0.44, N = 121, p = 0.015) and both scales had a wide range of scores. In this mixed cohort of patients, younger age was associated with higher SMC scores. There were no significant correlations between cognitive test performances and scales measuring subjective decline. Depression scores were significantly correlated to both scales measuring subjective decline. Linear regression models showed that age did not have a significant contribution to the variance in subjective memory beyond that of depressive symptoms. CONCLUSIONS: Measures for subjective cognitive decline are not interchangeable when used in memory clinics and the application of different scales in previous studies is an important factor as to why studies show variability in the association between subjective cognitive decline and background data and/or clinical results. Careful consideration should be taken as to which questions are relevant and have validity when operationalizing subjective cognitive decline.

Quantitative Electroencephalography as a Diagnostic Tool for Alzheimer's Dementia in Adults with Down Syndrome.

BACKGROUND: Assessment of dementia in individuals with intellectual disability is complex due to great inter-individual variability in cognitive function prior to dementia and a lack of standardized instruments. Studies have indicated that quantitative electroencephalography (qEEG) results may be used as a diagnostic marker for dementia. The aim of this study was to examine the value of qEEG in the diagnostic evaluation of dementia in patients with Down syndrome (DS). METHOD: The study included 21 patients with DS and mild-to-moderate dementia due to Alzheimer's disease (DS-AD) and 16 age-matched adults with DS without cognitive deterioration assessed by the informant-based Dementia Screening Questionnaire in Intellectual Disability (DSQIID). Conventional EEG was performed and analysed quantitatively using fast Fourier transformation. Outcomes were centroid frequency, peak frequency, absolute power, and relative power. RESULTS: In several regions of the brain, a significant decrease in the theta-1 band (4-7 Hz) was identified for the centroid frequency. A significant negative correlation was demonstrated between the mean of the centroid frequency of the theta-1 band and the total DSQIID score. CONCLUSION: We found that qEEG can detect a significant decrease in centroid frequency in a sample of patients with DS-AD as compared to a sample of adults with DS and no cognitive deterioration.

[Dementia in people with Down syndrome]. / Demens hos personer med Downs syndrom

In developed countries the population of elderly people with Down syndrome expands resulting in an increasing incidence of age-related diseases, including dementia. The assessment of dementia in individuals with intellectual disability is often complicated due to large intra-individual variability in cognitive functioning prior to dementia and to lack of standardised measures to detect dementia. Structured observations of symptoms of dementia and assessment techniques tailored for people with intellectual disability are increasingly needed.

Inadequate diagnostic evaluation in young patients registered with a diagnosis of dementia: a nationwide register-based study.

BACKGROUND: Establishing a diagnosis of dementia in young patients may be complex and have significant implications for the patient. The aim of this study was to evaluate the quality of the diagnostic work-up in young patients diagnosed with dementia in the clinical routine. METHODS: Two hundred patients were randomly selected from 891 patients aged ≤65 years registered with a diagnosis of dementia for the first time in 2008 in Danish hospitals, and 159 medical records were available for review. Three raters evaluated their medical records for the completeness of the diagnostic work-up on which the diagnosis of dementia had been based, using evidence-based guidelines for the diagnostic evaluation of dementia as reference standards. RESULTS: According to the rater review, only 111 (70%) patients met the clinical criteria for dementia. An acceptable diagnostic work-up including all items of recommended basic diagnostic evaluation was performed in only 24%, although more often (28%) in the subgroup of patients where dementia was confirmed by raters. CONCLUSION: This first nationwide study of unselected young patients registered with a diagnosis of dementia indicated that the concept of dementia may be misinterpreted by clinicians and that a diagnosis of dementia in the young is only rarely based on a complete basic diagnostic work-up, calling for increased competency.