Impairment in instrumental activities of daily living with high cognitive demand is an early marker of mild cognitive impairment: the Sydney memory and ageing study

BACKGROUND

Criteria for mild cognitive impairment (MCI) consider impairment in instrumental activities of daily living (IADL) as exclusionary, but cross-sectional studies suggest that some high-level functional deficits are present in MCI. This longitudinal study examines informant-rated IADL in MCI, compared with cognitively normal (CN) older individuals, and explores whether functional abilities, particularly those with high cognitive demand, are predictors of MCI and dementia over a 2-year period in individuals who were CN at baseline.

METHOD

A sample of 602 non-demented community dwelling individuals (375 CN and 227 with MCI) aged 70-90 years underwent baseline and 24-month assessments that included cognitive and medical assessments and an interview with a knowledgeable informant on functional abilities with the Bayer Activities of Daily Living Scale.

RESULTS

Significantly more deficits in informant-reported IADL with high cognitive demand were present in MCI compared with CN individuals at baseline and 2-year follow-up. Functional ability in CN individuals at baseline, particularly in activities with high cognitive demand, predicted MCI and dementia at follow-up. Difficulties with highly cognitively demanding activities specifically predicted amnestic MCI but not non-amnestic MCI whereas those with low cognitive demand did not predict MCI or dementia. Age, depressive symptoms, cardiovascular risk factors and the sex of the informant did not contribute to the prediction.

CONCLUSIONS

IADL are affected in individuals with MCI, and IADL with a high cognitive demand show impairment predating the diagnosis of MCI. Subtle cognitive impairment is therefore likely to be a major hidden burden in society.

The relationship of current depressive symptoms and past depression with cognitive impairment and instrumental activities of daily living in an elderly population: the Sydney Memory and Ageing Study

Depressive symptoms are common in the elderly and they have been associated with cognitive and functional impairment. However, relatively less is known about the relationship of a lifetime history of depression to cognitive impairment and functional status. The aim of this cross-sectional study was to assess whether current depressive symptoms and past depression are associated with cognitive or functional impairment in a community-based sample representative of east Sydney, Australia. We also examined whether there was an interaction between current and past depression in their effects on cognitive performance. Eight hundred non-demented aged participants received a neuropsychological assessment, a past psychiatric history interview and the 15-item Geriatric Depression Scale. The Bayer-Activities of Daily Living scale was completed by an informant to determine functional ability. Clinically relevant depressive symptoms were present in 6.1% of the sample and 16.6% reported a history of depression. Participants with current depression had significantly higher levels of psychological distress and anxiety, and lower life satisfaction and performed worse on memory and executive function compared to participants without current depression. After controlling for anxiety the effect on executive function was no longer significant while the effect on memory remained significant. A history of depression was associated with worse executive function, higher levels of psychological distress and anxiety, and lower life satisfaction. After controlling for psychological distress the effect of past depression on executive function was no longer significant. There were no significant interactions between current and past depression in their effects on cognitive performance. There were no differences between participants with or without current depression and with or without past depression on functional abilities. These results support the view that current and past depressive episodes are associated with poorer cognitive performance but not with functional abilities.

Functional alterations in brain activation and deactivation in mild cognitive impairment in response to a graded working memory challenge

AIM

To investigate dynamic changes in functional brain activity in mild cognitive impairment (MCI) in response to a graded working memory (WM) challenge with increasing memory load.

METHODS

In an event-related functional magnetic resonance imaging (fMRI) study, 35 MCI and 22 cognitively normal subjects performed a visuospatial associative WM task with 3 load levels. Potential performance differences were controlled for by individually calibrating the number of items presented at each load.

RESULTS

An interaction between group and WM load was observed during stimulus encoding. At lower loads, greater activity in the right anterior cingulate and right precuneus was observed in MCI subjects. As the load increased to higher levels, reduced activation in these regions and greater deactivation in the posterior cingulate-medial precuneus were observed in MCI compared to control subjects. Stronger expression of load-related patterns of activation and deactivation in MCI subjects was associated with greater clinical severity and a more abnormal pattern of performance variability.

CONCLUSION

Patterns of overactivation, underactivation and deactivation during successful encoding in MCI subjects were dependent on WM load. This type of graded cognitive challenge may operate like a 'memory stress test' in MCI and may be a useful biomarker of disease at the pre-dementia stage.

Hippocampal atrophy confounds template-based functional MR imaging measures of hippocampal activation in patients with mild cognitive impairment

BACKGROUND AND PURPOSE

Functional MR imaging has been used to study patterns of hippocampal activation that distinguish pathologic from normal memory loss in the elderly population. Our objective was to assess whether hippocampal atrophy confounds measurements of hippocampal activation in subjects with mild cognitive impairment (MCI).

METHODS

Twenty subjects with MCI and 20 elderly control subjects with objectively normal memory were studied at 4T during a face-name paradigm designed to activate the hippocampus. Hippocampal activation was measured using 2 separate approaches: applying a preset region of interest (ROI) in standardized template space and applying a manually drawn ROI in native subject space. Pearson correlation coefficients were calculated to compare group-dependent relationships between hippocampal volume and activation. Analysis of covariance (ANCOVA) was performed to assess group differences in hippocampal activation during encoding and retrieval. Age and hippocampal volume were included as covariates, as was a term for the interaction between hippocampal volume and group.

RESULTS

When hippocampal activation was measured by the template-based method, the correlation coefficient in the right hippocampus of subjects with MCI but not control subjects during retrieval differed significantly from zero. There was a significant (P < .05) group-by-volume interaction in the ANCOVA model. No significant correlations or interactions were demonstrated when activation was measured in native subject space with manually drawn ROIs.

CONCLUSION

Our findings suggest a potential confounding relationship between hippocampal volume and activation for subjects with MCI in template-based analyses. Template-based measures of hippocampal activation that do not adequately account for hippocampal atrophy should be used with caution in patients with MCI.

Consistency of handwriting movements in dementia of the Alzheimer's type: a comparison with Huntington's and Parkinson's diseases

Patients with dementia of the Alzheimer's type (DAT) and their matched controls wrote, on a computer graphics tablet, 4 consecutive, cursive letter 'l's, with varying levels of visual feedback: noninking pen and blank paper so that only the hand movements could be seen, noninking pen and lined paper to constrain their writing, goggles to occlude the lower visual field and eliminate all relevant visual feedback, and inking pen with full vision. The kinematic measures of stroke length, duration, and peak velocity were expressed in terms of consistency via a signal-to-noise ratio (M value of each parameter divided by its SD). Irrespective of medication or severity, DAT patients had writing strokes of significantly less consistent lengths than controls', and were disproportionately impaired by reduced visual feedback. Again irrespective of medication or severity, patients' strokes were of significantly less consistent duration, and significantly less consistent peak velocity than controls', independent of feedback conditions. Patients, unlike controls, frequently perseverated, producing more than 4 'l's, or multiple sets of responses, which was not differentially affected by level of visual feedback. The more variable performance of patients supports a degradation of the base motor program, and resembles that of Huntington's rather than Parkinson's disease patients. It may indeed reflect frontal rather than basal ganglia dysfunction.

Visual cues and the handwriting of older adults: a kinematic analysis

Kinematic techniques determined the nature of any age-related changes in the fluency of handwriting movements and also the extent to which any changes can be related to a differential utilization of visual feedback. To quantitatively document the kinematics of handwriting movements, 24 young and 24 older adults were compared by having them write simple cursive letter ls 4 times on a graphics tablet, under 4 different visual conditions (no vision, non inking pen, inking pen, and lined paper). Pen tip position was sampled at 200 Hz, from which kinematic indexes of movement efficiency and consistency were derived. Quantitative differences in movement trajectories were found in the older adults, who produced less efficient movements with a concomitant increased utilization of external visual cues. Older adults made a differential use of visual feedback to modify movement trajectories, rather than to control the effects of neural noise. Handwriting movements of older adults resembled only to a limited extent those of patients with Parkinson's disease.

Quality improvement in an era of managed care

As health care costs have escalated, government and business have become bold in their willingness to interfere in the clinical decision-making process in order to save money. Their tendency is to cut services, and physicians fear that the potential medical consequences of such cutbacks are only secondary considerations. These efforts threaten physician autonomy and authority. Doctors find themselves in an environment of uncertainty and vulnerability.

Visual cues and the handwriting of older adults: a kinematic analysis

Kinematic techniques determined the nature of any age-related changes in the fluency of handwriting movements and also the extent to which any changes can be related to a differential utilization of visual feedback. To quantitatively document the kinematics of handwriting movements, 24 young and 24 older adults were compared by having them write simple cursive letter ls 4 times on a graphics tablet, under 4 different visual conditions (no vision, non inking pen, inking pen, and lined paper). Pen tip position was sampled at 200 Hz, from which kinematic indexes of movement efficiency and consistency were derived. Quantitative differences in movement trajectories were found in the older adults, who produced less efficient movements with a concomitant increased utilization of external visual cues. Older adults made a differential use of visual feedback to modify movement trajectories, rather than to control the effects of neural noise. Handwriting movements of older adults resembled only to a limited extent those of patients with Parkinson's disease.