Simon L. Collinson

The Montreal Cognitive Assessment is superior to the Mini-Mental State Examination in detecting patients at higher risk of dementia.

BACKGROUND To examine the discriminant validity of the Montreal Cognitive Assessment (MoCA) and the Mini-Mental State Examination (MMSE) in detecting patients with cognitive impairment at higher risk for dementia at a memory clinic setting. METHODS Memory clinic patients were administered the MoCA, MMSE, and a comprehensive formal neuropsychological battery. Mild cognitive impairment (MCI) subtypes were dichotomized into two groups: single domain-MCI (sd-MCI) and multiple domain-MCI (md-MCI). Area under the receiver operating characteristic curve (ROC) analysis was used to compare the discriminatory ability of the MoCA and the MMSE. RESULTS Two hundred thirty patients were recruited, of which 136 (59.1%) were diagnosed with dementia, 61 (26.5%) with MCI, and 33 (14.3%) with no cognitive impairment (NCI). The majority of MCI patients had md-MCI (n = 36, 59%). The MoCA had significantly larger AUCs than the MMSE in discriminating md-MCI from the lower risk group for incident dementia (NCI and sd-MCI) [MoCA 0.92 (95% CI, 0.86-0.98) vs. MMSE 0.84 (95% CI, 0.75-0.92), p = 0.02). At their optimal cut-off points, the MoCA (19/20) remained superior to the MMSE (23/24) in detecting md-MCI [sensitivity: 0.83 vs. 0.72; specificity: 0.86 vs. 0.83; PPV: 0.79 vs. 0.72; NPV: 0.89 vs. 0.83; correctly classified: 85.1% vs. 78.7%]. CONCLUSION The MoCA is superior to the MMSE in the detection of patients with cognitive impairment at higher risk for incident dementia at a memory clinic setting.

Brief screening tests during acute admission in patients with mild stroke are predictive of vascular cognitive impairment 3–6 months after stroke

Objectives To determine the prognostic value of brief cognitive screening tests administered in the subacute stroke phase (initial 2 weeks) for the detection of significant cognitive impairment 3–6 months after stroke, the authors compared the Montreal Cognitive Assessment (MoCA) and the Mini-Mental State Examination (MMSE). Methods Patients with ischaemic stroke and transient ischaemic attack were assessed with both MoCA and MMSE within 14 days after index stroke, followed by a formal neuropsychological evaluation of seven cognitive domains 3–6 months later. Cognitive outcomes were dichotomised as either no–mild (impairment in ≤2 cognitive domains) or moderate–severe (impairment in ≥3 cognitive domains) vascular cognitive impairment. Area under the receiver operating characteristic (ROC) curve analysis was used to compare discriminatory ability. Results 300 patients were recruited, of whom 239 received formal neuropsychological assessment 3–6 months after the stroke. 60 (25%) patients had moderate–severe VCI. The overall discriminant validity for detection of moderate–severe cognitive impairment was similar for MoCA (ROC 0.85 (95% CI 0.79 to 0.90) and MMSE (ROC 0.83 (95% CI 0.77 to 0.89)), p=0.96). Both MoCA (21/22) and MMSE (25/26) had similar discriminant indices at their optimal cutoff points; sensitivity 0.88 versus 0.88; specificity 0.64 versus 0.67; 70% versus 72% correctly classified. Moreover, both tests had similar discriminant indices in detecting impaired cognitive domains. Conclusions Brief screening tests during acute admission in patients with mild stroke are predictive of significant vascular cognitive impairment 3–6 months after stroke.

Chronic Impairment of Prospective Memory after Mild Traumatic Brain Injury

Prospective memory (PM), the ability to recall future intentions, is crucial for independent living. Impairment of PM is a common complaint following head injury and is a significant impediment to good recovery, yet no studies have explored PM in mild traumatic brain injury (mTBI). In this study, prospective memory was examined in 31 mTBI patients and matched controls within a month of injury and 3 months after. mTBI patients performed more poorly than controls on the MIST task (Raskin, 2004) within the first month following injury, indicating that PM impairment is part of the acute cognitive sequelae of mTBI. These problems persisted beyond 3 months post-injury, suggesting that PM may be a sensitive indicator of cerebral compromise in mild brain injuries.

Metabolic Syndrome and the Risk of Mild Cognitive Impairment and Progression to Dementia: Follow-up of the Singapore Longitudinal Ageing Study Cohort

IMPORTANCE The association of the metabolic syndrome (MetS) and component cardiovascular risk factors with the risk of developing mild cognitive impairment (MCI) and MCI progression to dementia is not well established. OBJECTIVE To investigate the association of the MetS and its component cardiovascular risk factors with the incidence of MCI and its progression to dementia. DESIGN, SETTING, AND PARTICIPANTS Prospective longitudinal study from September 1, 2003, through December 31, 2009, in communities in 5 districts in the South East region of Singapore. Study participants were a population-based sample of 1519 cognitively normal adults 55 years and older. MAIN OUTCOMES AND MEASURES Prespecified outcomes were incident MCI and MCI progression to dementia. RESULTS The study cohort comprised 1519 participants. Their mean (SD) age was 64.9 (6.8) years, and 64.8% (n = 984) were female. Baseline characteristics associated with an increased risk of incident MCI were MetS (hazard ratio [HR], 1.46; 95% CI, 1.02-2.09), central obesity (HR, 1.41; 95% CI, 1.01-1.98), diabetes mellitus (HR, 2.84; 95% CI, 1.92-4.19), dyslipidemia (HR, 1.48; 95% CI, 1.01-2.15), and 3 or more component cardiovascular risk factors (HR, 1.58; 95% CI, 1.13-2.33). Baseline characteristics associated with an increased risk of MCI progression to dementia were MetS (HR, 4.25; 95% CI, 1.29-14.00), diabetes mellitus (HR, 2.47; 95% CI, 1.92-4.19), and 3 or more component cardiovascular risk factors (HR, 4.92; 95% CI, 1.39-17.4). CONCLUSIONS AND RELEVANCE The MetS was associated with an increased incidence of MCI and progression to dementia. Identifying individuals with diabetes mellitus or the MetS with or without MCI is a promising approach in early interventions to prevent or slow progression to dementia.

Metabolic Syndrome and Amnestic Mild Cognitive Impairment: Singapore Longitudinal Ageing Study-2 Findings

Metabolic syndrome (MetS) is reported to be associated with cognitive decline and dementia, in particular vascular dementia. However, the evidence linking MetS to Alzheimers disease (AD) and amnestic mild cognitive impairment (aMCI), a precursor of AD, is inconsistent and limited. This study examined the association of MetS and its components with aMCI and how APOE-εe4 and younger age influenced this association. Participants with aMCI (n = 98) and cognitively normal controls (n = 802) were identified from baseline data in a second wave cohort of older subjects aged 55 and over in the Singapore Longitudinal Ageing Study-2 (SLAS-2) in 2009/2010. The associations of MetS and its individual components with aMCI were analyzed using logistic regression controlling for age, gender, education, current smoking, alcohol drink, leisure time activities score, Geriatric Depression Scale score, APOE-ε4, and heart disease or stroke. The analysis was repeated for associations stratified by age and APOE-ε4 status. In multivariate analysis, MetS was associated with an elevated risk of aMCI (OR = 1.79; 95% CI 1.15-2.77). Among MetS components, central obesity showed a significant association with aMCI (OR = 1.77; 95% CI 1.11-2.82). The association between MetS and aMCI remained significant on repeated analysis among subjects free of heart disease and stroke. This association was particularly stronger among participants with APOE-ε4 allele (OR = 3.35; 95% CI, 1.03-10.85) and younger (<65 years) participants with APOE-ε4 (OR = 6.57; 95% CI, 1.03-41.74). MetS was found to be associated with aMCI, especially in individuals with APOE-ε4 at younger age in this middle-aged and older cohort.

Dichotic listening impairments in early onset schizophrenia are associated with reduced left temporal lobe volume

Dichotic listening (DL) impairments, in particular the loss or reduction of right ear advantage (REA) in people with schizophrenia have been variously interpreted as both a state and trait marker for schizophrenia. To date, there has been no comprehensive investigation of dichotic language impairments in relation to the structural integrity of the temporal cortex--the likely neural substrate for such impairments. In this study of 39 early onset patients and matched controls we used a dichotic listening procedure and examined the findings in relation to MRI measurements of gross and regional cerebral volumes. No overall group difference in ear advantage was found between patients and controls but patients who showed absence of REA also demonstrated an accompanying reduction of left temporal lobe volume compared with patients who showed normal ear advantage and controls. The findings suggest that impaired DL performance is a correlate of structural change in the temporal lobe and that this is apparent in early onset cases.

Physical Frailty, Cognitive Impairment, and the Risk of Neurocognitive Disorder in the Singapore Longitudinal Ageing Studies

Background The independent and combined effects of physical and cognitive domains of frailty in predicting the development of mild cognitive impairment (MCI) or dementia are not firmly established. Methods This study included cross-sectional and longitudinal analyses of physical frailty (Cardiovascular Health Study criteria), cognitive impairment (Mini-Mental State Examination [MMSE]), and neurocognitive disorder (DSM-5 criteria) among 1,575 community-living Chinese older adults from the Singapore Longitudinal Ageing Studies. Results At baseline, 2% were frail, 32% were prefrail, and 9% had cognitive impairment (MMSE score < 23). Frailty at baseline was significantly associated with prevalent cognitive impairment. Physical frailty categories were not significantly associated with incident NCD, but continuous physical frailty score and MMSE score showed significant individual and joint associations with incident mild NCD and dementia. Compared with those who were robust and cognitively normal, prefrail or frail old adults without cognitive impairment had no increased risk of incident NCD, but elevated odds of association with incident NCD were observed for robust with cognitive impairment (odds ratio [OR] = 4.04, p < .001), prefrail with cognitive impairment (OR = 2.22, p = .044), and especially for frail with cognitive impairment (OR = 6.37, p = .005). The prevalence of co-existing frailty and cognitive impairment (cognitive frailty) was 1% (95% confidence interval [CI]: 0.5-1.4), but was higher among participants aged 75 and older at 5.0% (95% CI: 1.8-8.1). Conclusions Physical frailty is associated with increased prevalence and incidence of cognitive impairment, and co-existing physical frailty and cognitive impairment confers additionally greater risk of incident NCD.

Corpus callosum morphology in first-episode and chronic schizophrenia: combined magnetic resonance and diffusion tensor imaging study of Chinese Singaporean patients

BACKGROUND Abnormalities in the corpus callosum have been reported in patients with schizophrenia for over 30 years but the influence of inter-individual differences and illness characteristics remains to be fully elucidated. AIMS To examine the influence of individual and illness characteristics on the corpus callosum in Chinese Singaporean patients with schizophrenia. METHOD Using magnetic resonance and diffusion tensor imaging, mean corpus callosum area, volume and fractional anisotropy were investigated in 120 Chinese Singaporean patients (52 with chronic and 68 with first-episode schizophrenia) and compared with data from 75 matched healthy controls. RESULTS Both area and volume were significantly reduced in patients relative to controls but no significant differences in corpus callosum existed between genders in either patients or controls. Differences in area and volume of the corpus callosum were greatest in patients whose condition was chronic relative to patients with a first episode and controls. Anterior callosum in patients, regardless of chronicity, was no different to that of controls. CONCLUSIONS Morphological abnormalities in the corpus callosum may increase with illness progression.

Cross-Cultural Application of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS): Performances of Elderly Chinese Singaporeans

There is a paucity of normative studies outside of North America and on elderly populations with very low education level. In the present study we examined the performance of poorly educated elderly on the Repeatable Battery Assessment of Neuropsychological Status (RBANS) with 352 cognitively normal elderly Chinese persons living in the community in Singapore who were enrolled in the Singapore Longitudinal Ageing Study (SLAS). Those with no formal education performed significantly less well than those with some years of formal education across four of five RBANS indices as well as the Total Scale score. Age- and education-adjusted normative data for the RBANS were established for the sample. The means and standard deviations of each of 12 subtests raw scores, five Index scores and the Total Scale score were calculated and stratified by age and education. Data from the present study should considerably advance the clinical utility of the RBANS in Chinese geriatric evaluations in Singapore, and can serve as a reference source for poorly educated elderly Chinese from around the region and beyond.

Arcuate Fasciculus Abnormalities and Their Relationship with Psychotic Symptoms in Schizophrenia

Disruption of fronto-temporal connections involving the arcuate fasciculus (AF) may underlie language processing anomalies and psychotic features such as auditory hallucinations in schizophrenia. No study to date has specifically investigated abnormalities of white matter integrity at particular loci along the AF as well as its regional lateralization in schizophrenia. We examined white matter changes (fractional anisotropy (FA), axial diffusivity (AD), asymmetry indices) along the whole extent of the AF and their relationship with psychotic symptoms in 32 males with schizophrenia and 44 healthy males. Large deformation diffeomorphic metric mapping and Fiber Assignment Continuous Tracking were employed to characterize FA and AD along the geometric curve of the AF. Our results showed that patients with schizophrenia had lower FA in the frontal aspects of the left AF compared with healthy controls. Greater left FA and AD lateralization in the temporal segment of AF were associated with more severe positive psychotic symptoms such as delusions and hallucinations in patients with schizophrenia. Disruption of white matter integrity of the left frontal AF and accentuation of normal left greater than right asymmetry of FA/AD in the temporal AF further support the notion of aberrant fronto-temporal connectivity in schizophrenia. AF pathology can affect corollary discharge of neural signals from frontal speech/motor initiation areas to suppress activity of auditory cortex that may influence psychotic phenomena such as auditory hallucinations and facilitate elaboration of delusional content.