Genetic analysis of cognitive preservation in the midwestern Amish reveals a novel locus on chromosome 2

INTRODUCTION

Alzheimer disease (AD) remains a debilitating condition with limited treatments and additional therapeutic targets needed. Identifying AD protective genetic loci may identify new targets and accelerate identification of therapeutic treatments. We examined a founder population to identify loci associated with cognitive preservation into advanced age.

METHODS

Genome-wide association and linkage analyses were performed on 946 examined and sampled Amish individuals, aged 76-95, who were either cognitively unimpaired (CU) or impaired (CI).

RESULTS

12 SNPs demonstrated suggestive association (P≤5×10-4) with cognitive preservation. Genetic linkage analyses identified >100 significant (LOD≥3.3) SNPs, some which overlapped with the association results. Only one locus on chromosome 2 retained significance across multiple analyses.

DISCUSSION

A novel significant result for cognitive preservation on chromosome 2 includes the genes LRRTM4 and CTNNA2. Additionally, the lead SNP, rs1402906, impacts the POU3F2 transcription factor binding affinity, which regulates LRRTM4 and CTNNA2.

Genetic variants in the SHISA6 gene are associated with delayed cognitive impairment in two family datasets

INTRODUCTION

Studies of cognitive impairment (CI) in Amish communities have identified sibships containing CI and cognitively unimpaired (CU) individuals. We hypothesize that CU individuals may carry protective alleles delaying age at onset (AAO) of CI.

METHODS

A total of 1522 individuals screened for CI were genotyped. The outcome studied was AAO for CI individuals or age at last normal exam for CU individuals. Cox mixed-effects models examined association between age and single nucleotide variants (SNVs).

RESULTS

Three SNVs were significantly associated (P < 5 × 10-8 ) with AAO on chromosomes 6 (rs14538074; hazard ratio [HR] = 3.35), 9 (rs534551495; HR = 2.82), and 17 (rs146729640; HR = 6.38). The chromosome 17 association was replicated in the independent National Institute on Aging Genetics Initiative for Late-Onset Alzheimer's Disease dataset.

DISCUSSION

The replicated genome-wide significant association with AAO on chromosome 17 is located in the SHISA6 gene, which is involved in post-synaptic transmission in the hippocampus and is a biologically plausible candidate gene for Alzheimer's disease.

Effect of intensive blood pressure control on subtypes of mild cognitive impairment and risk of progression from SPRINT study

BACKGROUND

To examine the effect of intensive blood pressure control on the occurrence of subtypes of mild cognitive impairment (MCI) and determine the risk of progression to dementia or death.

METHODS

Secondary analysis of a randomized trial of community-dwelling adults (≥50 years) with hypertension. Participants were randomized to a systolic blood pressure (SBP) goal of <120 mm Hg (intensive treatment; n = 4678) or <140 mm Hg (Standard treatment; n = 4683). Outcomes included adjudicated MCI, MCI subtype (amnestic, non-amnestic, multi-domain, single domain), and probable dementia. Multistate survival models were used to examine transitions in cognitive status accounting for the competing risk of death.

RESULTS

Among 9361 randomized participants (mean age, 67.9 years; 3332 women [35.6%]), 640 participants met the protocol definition for MCI, with intensive treatment reducing the risk of MCI overall (hazard ratio [HR], 0.81 [95% confidence interval {CI}, 0.69-0.94]), as previously reported. This effect was largely reflected in amnestic subtypes (HR, 0.78 [95% CI, 0.66-0.92]) and multi-domain subtypes (HR, 0.78 [95% CI, 0.65-0.93]). An adjudication of MCI, as compared with normal cognitive function, substantially increased the probability of progressing to probable dementia (5.9% [95% CI: 4.5%-7.7%] vs. 0.6% [95% CI: 0.3%-0.9%]) and to death (10.0% [95% CI: 8.3%-11.9%] vs. 2.3% [95% CI: 2.0%-2.7%]) within 2 years.

CONCLUSIONS

Intensive treatment reduced the risk for amnestic and multi-domain subtypes of MCI. An adjudication of MCI was associated with increased risk of progression to dementia and death, highlighting the relevance of MCI as a primary outcome in clinical and research settings.

Association of Intensive vs Standard Blood Pressure Control With Cerebral White Matter Lesions

Importance

The effect of intensive blood pressure lowering on brain health remains uncertain.

Objective

To evaluate the association of intensive blood pressure treatment with cerebral white matter lesion and brain volumes.

Design, Setting, and Participants

A substudy of a multicenter randomized clinical trial of hypertensive adults 50 years or older without a history of diabetes or stroke at 27 sites in the United States. Randomization began on November 8, 2010. The overall trial was stopped early because of benefit for its primary outcome (a composite of cardiovascular events) and all-cause mortality on August 20, 2015. Brain magnetic resonance imaging (MRI) was performed on a subset of participants at baseline (n = 670) and at 4 years of follow-up (n = 449); final follow-up date was July 1, 2016.

Interventions

Participants were randomized to a systolic blood pressure (SBP) goal of either less than 120 mm Hg (intensive treatment, n = 355) or less than 140 mm Hg (standard treatment, n = 315).

Main Outcomes and Measures

The primary outcome was change in total white matter lesion volume from baseline. Change in total brain volume was a secondary outcome.

Results

Among 670 recruited patients who had baseline MRI (mean age, 67.3 [SD, 8.2] years; 40.4% women), 449 (67.0%) completed the follow-up MRI at a median of 3.97 years after randomization, after a median intervention period of 3.40 years. In the intensive treatment group, based on a robust linear mixed model, mean white matter lesion volume increased from 4.57 to 5.49 cm3 (difference, 0.92 cm3 [95% CI, 0.69 to 1.14]) vs an increase from 4.40 to 5.85 cm3 (difference, 1.45 cm3 [95% CI, 1.21 to 1.70]) in the standard treatment group (between-group difference in change, -0.54 cm3 [95% CI, -0.87 to -0.20]). Mean total brain volume decreased from 1134.5 to 1104.0 cm3 (difference, -30.6 cm3 [95% CI, -32.3 to -28.8]) in the intensive treatment group vs a decrease from 1134.0 to 1107.1 cm3 (difference, -26.9 cm3 [95% CI, 24.8 to 28.8]) in the standard treatment group (between-group difference in change, -3.7 cm3 [95% CI, -6.3 to -1.1]).

Conclusions and Relevance

Among hypertensive adults, targeting an SBP of less than 120 mm Hg, compared with less than 140 mm Hg, was significantly associated with a smaller increase in cerebral white matter lesion volume and a greater decrease in total brain volume, although the differences were small.

Trial Registration

ClinicalTrials.gov Identifier: NCT01206062.

Effect of Intensive vs Standard Blood Pressure Control on Probable Dementia: A Randomized Clinical Trial

IMPORTANCE

There are currently no proven treatments to reduce the risk of mild cognitive impairment and dementia.

OBJECTIVE

To evaluate the effect of intensive blood pressure control on risk of dementia.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial conducted at 102 sites in the United States and Puerto Rico among adults aged 50 years or older with hypertension but without diabetes or history of stroke. Randomization began on November 8, 2010. The trial was stopped early for benefit on its primary outcome (a composite of cardiovascular events) and all-cause mortality on August 20, 2015. The final date for follow-up of cognitive outcomes was July 22, 2018.

INTERVENTIONS

Participants were randomized to a systolic blood pressure goal of either less than 120 mm Hg (intensive treatment group; n = 4678) or less than 140 mm Hg (standard treatment group; n = 4683).

MAIN OUTCOMES AND MEASURES

The primary cognitive outcome was occurrence of adjudicated probable dementia. Secondary cognitive outcomes included adjudicated mild cognitive impairment and a composite outcome of mild cognitive impairment or probable dementia.

RESULTS

Among 9361 randomized participants (mean age, 67.9 years; 3332 women [35.6%]), 8563 (91.5%) completed at least 1 follow-up cognitive assessment. The median intervention period was 3.34 years. During a total median follow-up of 5.11 years, adjudicated probable dementia occurred in 149 participants in the intensive treatment group vs 176 in the standard treatment group (7.2 vs 8.6 cases per 1000 person-years; hazard ratio [HR], 0.83; 95% CI, 0.67-1.04). Intensive BP control significantly reduced the risk of mild cognitive impairment (14.6 vs 18.3 cases per 1000 person-years; HR, 0.81; 95% CI, 0.69-0.95) and the combined rate of mild cognitive impairment or probable dementia (20.2 vs 24.1 cases per 1000 person-years; HR, 0.85; 95% CI, 0.74-0.97).

CONCLUSIONS AND RELEVANCE

Among ambulatory adults with hypertension, treating to a systolic blood pressure goal of less than 120 mm Hg compared with a goal of less than 140 mm Hg did not result in a significant reduction in the risk of probable dementia. Because of early study termination and fewer than expected cases of dementia, the study may have been underpowered for this end point.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01206062.

Quality of Life and Deficit Identification in Dementia

Numerous studies have examined self-identification of deficits in persons with dementia. Few of these studies consider the influence of interpersonal and social factors on deficit identification, and most focus on whether or why deficits are ‘underreported’ by persons with dementia. In our studies, we found considerable variation in deficit identification within and among persons with dementia, and some ‘overreporting’ of deficits in comparison with caregiver reports across all of the domains studied. Thus, focusing on ‘underreporting’ and aggregate level data neglects information that could be important to measuring and understanding quality of life in dementia. Current approaches to measuring and understanding quality of life in dementia make divergent assumptions about the impact of deficit identification. Emerging phenomenological perspectives suggest that proactive interventions that treat deficit identification as an interpersonal and social challenge inherent in the experience of dementia would enhance the quality of life of caregiving dyads.

Five-months-postoperative neuropsychological outcome from a pilot prospective randomized clinical trial of thalamic deep brain stimulation for Tourette syndrome

OBJECTIVE

Tourette syndrome (TS) is a neuropsychiatric disorder presenting with motor and/or sonic tics associated with frontostriatal dysfunction. This study provided pilot data of the neuropsychological safety of bilateral thalamic deep brain stimulation (DBS) to treat medication-refractory TS in adults.

METHOD

This study used a repeated-measures design with pretest and 3-month follow-up from start of continuous bilateral DBS. Five male patients underwent DBS surgery for medically refractory TS. Repeated-measures ANOVA was used to evaluate for any change in neuropsychological test scores, employing a false discovery rate. Outcome measures included 14 neuropsychological tests assessing psychomotor speed, attention, memory, language, visuoconstructional, and executive functions, as well as subjective mood ratings of depression and anxiety.

RESULTS

Average age was 28.2 years (SD = 7.5) with 12-17 years of education. Participants were disabled by tics, with a tic frequency of 50-80 per minute before surgery. At baseline, subjects' cognitive function was generally average, although mild deficits in sequencing and verbal fluency were present, as were clinically mild obsessive-compulsive symptoms. At 3 months of continuous DBS (5 months after implantation), 3 of 5 participants had clinical reductions in motor and sonic tics. Cognitive scores generally remained stable, but declines of moderate to large effect size (Cohen's d > 0.6) in verbal fluency, visual immediate memory, and reaction time were observed. Fewer symptoms of depression and anxiety, as well as fewer obsessions and compulsions, were reported after 3 months of continuous high-frequency DBS.

CONCLUSIONS

Bilateral centromedian-parafascicular thalamic DBS for medically refractory TS shows promise for treatment of medically refractory TS without marked neuropsychological morbidity. Symptoms of depression and anxiety improved.

Influence of mild cognitive impairment on visual word recognition

The present study examined the effects of normal aging and mild cognitive impairment (MCI) on visual word recognition. Madden et al. (1999) reported evidence of general slowing of cognitive processes in Alzheimer's disease (AD) patients relative to younger adults and healthy older adults using a lexical decision task. It was of interest to determine whether similar effects would be observed in MCI patients relative to healthy younger and older adults. We extended the lexical decision task paradigm developed by Allen et al. (2004b) on younger adults to an examination of the effect(s) of MCI on visual word recognition. Results from the present study showed that healthy older adults and MCI patients performed similarly. That is, both groups took longer than younger adults to process words presented in mixed-case than in consistent-case letters. Mild cognitive impairment patients, however, responded significantly more slowly than healthy older adults across all lexical decision task conditions and showed a trend toward larger case-mixing effects than healthy older adults, which suggests that MCI may result in poorer analytic processing ability. Based on the current findings, evidence of a generalized slowing of cognitive processes using a standard lexical decision task can be expanded to include not only AD patients, but also the preclinical stages of the disease as well.

Associations Between Dementia/Mild Cognitive Impairment and Cognitive Performance and Activity Levels in Youth

OBJECTIVES

To study the associations between dementia/mild cognitive impairment (MCI) and cognitive performance and activity levels in youth.

DESIGN

Retrospective cohort study.

SETTING

Research volunteers living throughout the United States.

PARTICIPANTS

A total of 396 persons (mean age 75) who were graduates of the same high school in the mid-1940s.

MEASUREMENTS

Adolescent intelligence quotient (IQ) scores were gathered from archived student records, and activity levels were determined from yearbooks. A two-stage telephone screening procedure (Modified Telephone Interview for Cognitive Status or Informant Questionnaire on Cognitive Decline in the Elderly followed by Dementia Questionnaire) was used to determine adult cognitive status. Data were analyzed using logistic regression to model the risk of cognitive impairment (dementia/MCI) versus no cognitive impairment as a function of IQ and activity level, adjusting for sex and education.

RESULTS

High adolescent IQ and greater activity level were each independently associated with a lower risk for dementia/MCI (odds ratio (OR) for a 1-standard deviation increase in IQ=0.51, 95% confidence interval (CI)=0.32-0.79; OR for a unit increase in activity=0.32, 95% CI=0.12-0.84). No association was found between sex or education and adult cognitive status in this model.

CONCLUSION

High IQ and greater activity levels in youth reduce the risk for cognitive impairments in aging. The mechanism(s) underlying these associations are unknown, but intelligence may be a marker for cognitive/neurological "reserve," and involvement in activities may contribute to "reserve." Early neuropathology and ascertainment bias are also possible explanations for the observed associations.

Effects of educational attainment and occupational status on cognitive and functional decline in persons with Alzheimer-type dementia

Researchers have suggested that educational attainment and occupational status--indicators of cognitive and/or neurologic "reserve"--can help persons compensate for clinical manifestations of Alzheimer's disease (AD), such as the rates of cognitive and functional decline. The effects of educational attainment on rates of decline could be "direct" independent of occupational status), "indirect" (working through occupational status), or both. We used multilevel analysis for repeated measures to study the effects of educational attainment and occupational status on rates of decline in cognition (Mini-Mental State Examination, MMSE) and function (Cleveland Scale for Activities of Daily Living). Subjects included persons with "probable" or "possible" AD, drawn from our Alzheimer's Disease Research Center registry (N = 482 in the analysis of cognitive decline, and N = 450 in the analysis of functional decline). When controlling for year of birth, gender, ethnicity, and duration of illness, we found that there was an inverse relationship between number of years of education and rate of decline in MMSE, but effects of occupational status were not significant. This implies a "direct" effect of education on decline in MMSE, but no "indirect" effect through occupational status. Neither educational attainment nor occupational status affected rate of decline in functional ability. We conclude that education slows the rate of cognitive decline in persons with AD, but not through its impact on occupational status. Thus, the protective effects of reserve may be established early in life, before people enter the workforce.

Visual exploration of facial emotion by healthy older adults and patients with Alzheimer disease

OBJECTIVE

The purpose of this study was to investigate eye movement patterns of patients with Alzheimer disease (AD) and healthy older adults while viewing photographs of facial expression.

BACKGROUND

Individuals with Alzheimer disease appear to have deficits in emotion perception, but the underlying mechanisms are not understood well. It is not known whether individuals with AD visually explore facial stimuli and extract information needed to make emotion identification from faces in the same way as do healthy older adults.

METHOD

Seventeen AD patients and 15 older adult control patients were shown faces that depicted different emotions and were asked to identify the emotion displayed from two alternatives. The eye movements of participants were recorded during the emotion identification task.

RESULTS

No differences were seen between AD patients and older adult controls regarding their accuracy of emotion identification. However, AD patients differed from older adult controls on eye movement patterns during the emotion identification task. Alzheimer disease patients fixated less on the face and, in particular, on the eyes. Alzheimer disease patients also spent more time viewing areas off the face. There was no relationship between the severity of cognitive impairment and emotion identification or eye movement patterns.

CONCLUSIONS

Although the AD patients and older adult controls showed similar accuracy for the emotion identification task, their visual processing strategies differed. Relative to older adult controls, AD patients fixated less on discriminating regions and attended more to irrelevant aspects of stimuli. The eye movement differences were particularly evident in AD patients who did more poorly for the emotion identification task. These differences were not attributable to the global cognitive deterioration accompanying AD, but suggested a specific deficit in visual processing abilities.

Confirmation of an association between family history of affective disorder and the depressive syndrome in Alzheimer's disease

OBJECTIVE

The authors' goal was to replicate an earlier finding of a familial liability for depression in Alzheimer's disease.

METHOD

The family histories of depression and dementia were compared in 28 patients experiencing a first episode of major depression after onset of Alzheimer's disease and 74 nondepressed patients with Alzheimer's disease.

RESULTS

Significantly more families of depressed dementia patients included depressed first-degree relatives. There was no difference between Alzheimer's disease patients with and without depression in the proportion of families with a history of dementia.

CONCLUSIONS

Major depression in Alzheimer's disease is associated with a familial liability for depression that is independent of any familial liability for dementia.

Sources of stress for family caregivers of institutionalized dementia patients

Although many caregivers place their relative in a nursing home in an attempt to reduce their own burden, caregiving stress often continues after institutionalization. This research examined sources of stress for 66 caregivers who cared for their impaired relative at home and later placed that individual in a nursing home. We hypothesized that although these caregivers no longer had primary responsibility for direct care, they would continue to experience distress because of the stressors associated with the nursing home. Results ran counter to our expectations. Although many caregivers reported stressors related to nursing home care, stressors stemming from the patient's Alzheimer's disease (AD) symptoms accounted for more variance in caregivers' levels of anxiety and depression, and in the quality of their interpersonal relations. Even though caregivers were assisted in their caregiving responsibilities by the nursing home staff, their relative's AD symptoms continued to prompt distress.

Stressors and well-being among caregivers to older adults with dementia: the in-home versus nursing home experience

We examined differences in stressors and well-being for caregivers who care for a relative with dementia at home and those who had placed their relative in a nursing home. The groups did not differ in depression or somatic complaints, but nursing home caregivers had fewer social and interpersonal disruptions. Controlling for caregiving problems, nursing home caregivers reported more stressors due to ADL (activities of daily living) assistance, their relatives' behavioral and cognitive functioning, and lack of caregiving support from family and friends.