The closing-in phenomenon in the drawing performance of Alzheimer's disease patients: A compensation account

Idiopathic normal pressure hydrocephalus diagnosis: Quantitative and qualitative score predicting outcome of extended lumbar drainage

Image 1.

Eye-Tracking Metrics for Figure-Copying Processes in Early- vs. Late-Onset Alzheimer's Disease

Visuospatial dysfunction is a common symptom in patients with Alzheimer's disease (AD). To more focus on copying processes rather than on finally completed figures, we conceptually split the copying processes into three stages: visuoperceptual function, visuoconstructional function, and working memory function. We constructed perceptual and working spaces to investigate the different stages of copying, and then, we compared the number and duration of fixations and saccades and the number of switches across the two spaces. We used eye-tracking glasses to assess eye-tracking metrics in patients with early-onset AD (EOAD), patients with late-onset AD (LOAD), and normal control (NC) participants while they copied the simplified Rey–Osterrieth complex figure test (RCFT). Regarding eye metrics on the perceptual space, the number and duration of fixations were greater in both groups of patients with AD than in the NC participants group (number: EOAD vs. NC: p < 0.001, LOAD vs. NC: p = 0. 003/ duration: EOAD vs. NC: p < 0.001, LOAD vs. NC: p < 0.001). On the working space, the number and duration of fixations were greater in the patients with EOAD than in the patients with LOAD and NC participants (number: EOAD vs. LOAD: p = 0. 007, EOAD vs. NC: p = 0. 001/duration: EOAD vs. LOAD: p = 0. 008, EOAD vs. NC: p = 0. 002). The number of saccades and switching was higher in patients with EOAD than in NC participants (p < 0.001). The eye-tracking metrics from the simplified RCFT correlated with the neuropsychological test scores. Patients with EOAD and LOAD achieved the same level of performance at the simplified and original RCFT scores. However, patients with EOAD than LOAD showed a greater number and duration of fixations on the working space and more frequent switching between the perceptual and working spaces, which may reflect more cognitive efforts to achieve the same level of performance.

Ventral Tegmental Area Disconnection Contributes Two Years Early to Correctly Classify Patients Converted to Alzheimer's Disease: Implications for Treatment

BACKGROUND

Recent cross-sectional studies highlighted the loss of dopaminergic neurons in the ventral tegmental area (VTA) as an early pathophysiological event in Alzheimer's disease (AD).

OBJECTIVE

In this study, we longitudinally investigated by resting-state fMRI (rs-fMRI) a cohort of patients with mild cognitive impairment (MCI) due to AD to evaluate the impact of VTA disconnection in predicting the conversion to AD.

METHODS

A cohort of 35 patients with MCI due to AD were recruited and followed-up for 24 months. They underwent cognitive evaluation and rs-fMRI to assess VTA connectivity at baseline and at follow-up.

RESULTS

At 24-month follow-up, 16 out of 35 patients converted to AD. Although converters and non-converters to AD did not differ in demographic and behavioral characteristics at baseline, the first group showed a significant reduction of VTA-driven connectivity in the posterior cingulate and precentral cortex. This pattern of additional disconnection in MCI-Converters compared to non-converters remained substantially unchanged at 24-month follow-up.

CONCLUSION

This study reinforces the hypothesis of an early contribution of dopaminergic dysfunction to AD evolution by targeting the default-mode network. These results have potential implications for AD staging and prognosis and support new opportunities for therapeutic interventions to slow down disease progression.

A Comprehensive Evaluation of the Process of Copying a Complex Figure in Early- and Late-Onset Alzheimer Disease: A Quantitative Analysis of Digital Pen Data

Background

The Rey-Osterrieth Complex Figure Test (RCFT) is a neuropsychological test that is widely used to assess visual memory and visuoconstructional deficits in patients with cognitive impairment, including Alzheimer disease (AD). Patients with AD have an increased tendency for exhibiting extraordinary behaviors in the RCFT for selecting the drawing area, organizing the figure, and deciding the order of images, among other activities. However, the conventional scoring system based on pen and paper has a limited ability to reflect these detailed behaviors.

Objective

This study aims to establish a scoring system that addresses not only the spatial arrangement of the finished drawing but also the drawing process of patients with AD by using digital pen data.

Methods

A digital pen and tablet were used to copy complex figures. The stroke patterns and kinetics of normal controls (NCs) and patients with early-onset AD (EOAD) and late-onset AD (LOAD) were analyzed by comparing the pen tip trajectory, spatial arrangement, and similarity of the finished drawings.

Results

Patients with AD copied the figure in a more fragmented way with a longer pause than NCs (EOAD: P=.045; LOAD: P=.01). Patients with AD showed an increased tendency to draw the figures closer toward the target image in comparison with the NCs (EOAD: P=.005; LOAD: P=.01) Patients with AD showed the lower accuracy than NCs (EOAD: P=.004; LOAD: P=.002). Patients with EOAD and LOAD showed similar but slightly different drawing behaviors, especially in space use and in the initial stage of drawing.

Conclusions

The digitalized complex figure test evaluated copying performance quantitatively and further elucidated the patients’ ongoing process during copying. We believe that this novel approach can be used as a digital biomarker of AD. In addition, the repeatability of the test will delineate the process of executive functions and constructional organization abilities with disease progression.

Closing-In Behavior and Motor Distractibility in Persons with Brain Injury

OBJECTIVE

This study investigates closing-in behavior (CIB), a phenomenon observed in graphic copying tasks when responses encroach upon or overlap the model. The behavior is most common amongst individuals with dementia and amongst pre-school children. We explored the relationship between CIB and the 'distractor effect' in reaching, whereby salient visual stimuli can influence the spatial trajectory of the reach.

METHOD

A group of individuals with overlap-CIB (n = 9), without CIB (n = 9) and healthy controls (HC; n = 6) underwent a task-irrelevant and a task-relevant distractors and the deviation of the movement trajectory towards the distractor location was measured in both tasks.

RESULTS

Individuals with graphic CIB showed more distractor-directed veering during reaching than did individuals without CIB or HC, provided that the distractor was relevant for the reaching task.

CONCLUSIONS

These results strengthen the relationship between CIB and the distractor effect and reinforce the hypothesis that CIB represents a disinhibited tendency to act towards the focus of attention.

Closing-in Phenomenon in Huntington's Disease: A Neuropsychological Marker of Frontal/Executive Dysfunction

Objective

In visuo-constructional tasks, patients may reproduce drawings near-to or superimposed on a model, showing the so-called "Closing-in" (CI), often ascribed to a defect in inhibitory control. CI has been described in neurological conditions, but no studies have explored CI in Huntington's disease (HD), a neurodegenerative disorder often involving the frontal cortical-subcortical circuits. We searched for the occurrence of CI in HD patients and systematically investigated its correlates to find a clinical marker of the frontal/executive dysfunctions in the early examination of HD patients.

Method

We assessed 130 HD participants, who performed a graphic coping task and a neuropsychological, psychiatric, motor, and functional assessment.

Results

CI occurred in 52/130 (40%) HD patients, with 43/52 (82.7%) superimposing their copy directly on the model. MANOVA showed that HD patients with CI scored significantly poorer on Symbol digit modality test, Stroop-color word - reading test, Stroop-color word - interference test, Trail making test - part B, and Phonological verbal fluency test. However, a logistic regression analysis revealed that the significant predictor of the occurrence of CI was the score on Stroop-color word - interference test.

Conclusions

HD patients may show CI in graphic tasks, and it could be related to a defect in inhibitory control impeding the switch of attention from the model to the copying space, and releasing a default tendency which causes an attraction of hand movement towards the focus of visual attention. CI might be a useful clinical marker for the early detection of frontal/executive defects in HD patients.

Closing-in Behavior and Parietal Lobe Deficits: Three Single Cases Exhibiting Different Manifestations of the Same Behavior

Closing-in behavior (CIB) is observed in copying tasks (graphic or gestural) when the copy is performed near or on the top of the model. This symptom has been classically considered to be a manifestation of constructional apraxia and is often associated with a visuospatial impairment. More recent work emphasizes the attentional and/or executive nature of the behavior and its association with frontal lobe dysfunction. We describe three patients in whom CIB was associated with posterior parietal deficits of different etiologies (stroke in Patient 1 and dementia in Patients 2 and 3). In copying figures, Patient 1 produced the shape with high accuracy but the rendering overlapped the model, while for Patients 2 and 3 the copies were distorted but overlapping or in close proximity to the target. In gesture imitation, Patient 2 performed the gestures toward the examiner's space, while Patient 1 showed a peculiar form of CIB: when he was asked to place the ipsilesional arm in a position that mirrored the contralesional hand, Patient 1 moved his hand toward his contralesional hand. Patient 3 did not present gestural CIB. While CIB in Patient 1 was associated with selective deficits in executive functions and attention, additional visuospatial deficits were observed in Patients 2 and 3. The latter two patients showed a general visuoconstructional deficit. These case studies support a primary attentional account of CIB but also suggest that visuoconstructional impairments may contribute to the emergence of CIB, in some subjects. This evidence argues for different types of CIB with different cognitive and neural underpinnings. Furthermore, the data support the hypothesis of a differential involvement of fronto-parietal network in CIB.

Damage to the Frontal Aslant Tract Accounts for Visuo-Constructive Deficits in Alzheimer's Disease

The frontal aslant tract (FAT) has been described as a bundle connecting the Broca's area to the supplementary motor area (SMA) and the pre-SMA in both hemispheres. The functional properties of this tract and its role in degenerative dementia, such as Alzheimer's disease (AD), still need to be fully clarified. The aim of this study was to explore the microstructural integrity of the FAT in patients with AD and its potential relationship with cognitive functioning. Twenty-three patients with AD and 25 healthy subjects (HS) were enrolled. All subjects underwent cognitive and MRI examination. MRI, including diffusion sequences, was used for probabilistic tractography analysis. We reconstructed individual FATs bilaterally and assessed their microstructural integrity using fractional anisotropy (FA), computed as both mean tract value and voxel-wise using SPM-8. Mean FA values were then used to test for correlations with cognitive measures. Mean tract FA and voxel-wise analyses revealed that patients with AD, compared to HS, had decreased FA in the FAT bilaterally. In addition, positive associations were found between FA in the FATs and patients' performance at tests for constructional praxis and visuospatial logical reasoning. The present results reveal a bilateral damage of FAT in AD patients. The association between FATs' microscopic abnormalities and constructive abilities fits well with the knowledge of a functional involvement of SMA and pre-SMA in movement sequences when executing constructive praxis tasks. The FAT is an associative bundle critically involved in the network sub-serving constructional praxis in patients with AD.

Thinking inside the box: Spatial frames of reference for drawing in Williams syndrome and typical development

BACKGROUND

Successfully completing a drawing relies on the ability to accurately impose and manipulate spatial frames of reference for the object that is being drawn and for the drawing space. Typically developing (TD) children use cues such as the page boundary as a frame of reference to guide the orientation of drawn lines. Individuals with Williams syndrome (WS) typically produce incohesive drawings; this is proposed to reflect a local processing bias.

AIMS

Across two studies, we provide the first investigation of the effect of using a frame of reference when drawing simple lines and shapes in WS and TD groups (matched for non-verbal ability).

METHODS AND PROCEDURES

Individuals with WS (N=17 Experiment 1; N=18 Experiment 2) and TD children matched by non-verbal ability drew single lines (Experiment One) and whole shapes (Experiment Two) within a neutral, incongruent or congruent frame. The angular deviation of the drawn line/shape, relative to the model line/shape, was measured.

OUTCOMES AND RESULTS

Both groups were sensitive to spatial frames of reference when drawing single lines and whole shapes, imposed by a frame around the drawing space.

CONCLUSIONS AND IMPLICATIONS

A local processing bias in WS cannot explain poor drawing performance in WS.

Bimanual Gesture Imitation in Alzheimer's Disease

BACKGROUND/OBJECTIVE

Unimanual gesture production or imitation has often been studied in Alzheimer's disease (AD) during apraxia testing. In the present study, it was hypothesized that bimanual motor tasks may be a sensitive method to detect impairments of motor cognition in AD due to increased demands on the cognitive system.

METHODS

We investigated bimanual, meaningless gesture imitation in 45 AD outpatients, 38 subjects with mild cognitive impairment (MCI), and 50 normal controls (NC) attending a memory clinic. Participants performed neuropsychological background testing and three tasks: the Interlocking Finger Test (ILF), Imitation of Alternating Hand Movements (AHM), and Bimanual Rhythm Tapping (BRT).

RESULTS

The tasks were short and easy to administer. Inter-rater reliability was high across all three tests. AD patients performed significantly poorer than NC and MCI participants; a deficit to imitate bimanual gestures was rarely found in MCI and NC participants. Sensitivity to detect AD ranged from 0.5 and 0.7, specificity beyond 0.9. ROC analyses revealed good diagnostic accuracy (0.77 to 0.92). Impairment to imitate bimanual gestures was mainly predicted by diagnosis and disease severity.

CONCLUSION

Our findings suggest that an impairment to imitate bimanual, meaningless gestures is a valid disease marker of mild to moderate AD and can easily be assessed in memory clinic settings. Based on our preliminary findings, it appears to be a separate impairment which can be distinguished from other cognitive deficits.

Drawing Disorders in Alzheimer's Disease and Other Forms of Dementia

Drawing is a multicomponential process that can be impaired by many kinds of brain lesions. Drawing disorders are very common in Alzheimer's disease and other forms of dementia, and can provide clinical information for the distinction of the different dementing diseases. In our review we started from an overview of the neural and cognitive bases of drawing, and from a recollection of the drawing tasks more frequently used for assessing individuals with dementia. Then, we analyzed drawing disorders in dementia, paying special attention to those observed in Alzheimer's disease, from the prodromal stages of the amnesic mild cognitive impairment to the stages of full-blown dementia, both in the sporadic forms with late onset in the entorhino-hippocampal structures and in those with early onset in the posterior neocortical structures. We reviewed the drawing features that could differentiate Alzheimer's disease from vascular dementia and from the most frequent forms of degenerative dementia, namely frontotemporal dementia and Lewy body disease. Finally, we examined some peculiar aspects of drawing disorders in dementia, such as perseverations, rotations, and closing-in. We argue that a careful analysis of drawing errors helps to differentiate the different forms of dementia more than overall accuracy in drawing.

Relationships between Environmental Dependency and Closing-in in Patients with Fronto-temporal Dementia

Environmental dependency (ED) phenomena, including utilization behavior and imitation behavior, are clinical manifestations typically observed in patients with the behavioral variant of fronto-temporal dementia (bvFTD), who may also show the closing-in (CI) phenomenon. Here, we explored the neuropsychological correlates of ED and CI in bvFTD, and the association of ED with CI to clarify the mechanisms underlying these clinical manifestations. Thirty-one bvFTD patients underwent a wide cognitive assessment in addition to special tasks to detect occurrence of CI and ED phenomena. Both ED and CI phenomena were present in more than half of the sample. Logistic regression analyses revealed that both ED and CI phenomena were significantly associated with poor scores on frontal neuropsychological tests. Although ED and CI often co-occurred, 3/12 patients with CI did not show ED, and 5/18 patients with ED did not show CI. A logistic regression model showed that the presence of ED was not significantly associated to CI. CI and ED are associated to progressive derangement of frontal functions in bvFTD. However, specific frontal dysfunctions might explain the occurrence of either phenomenon in isolation.

Frontal-executive constructional apraxia: when delayed recall is better than copying

In assessments of visuospatial function and memory, patients are often required to copy a figure and later to reproduce that figure from memory. Whereas most people perform better on a copying task than when drawing from memory, in this study we describe an unusual pattern of performance in which patients are better at drawing from memory than copying. Consecutive patients in a neurocognitive disorders clinic were given a battery of clinical cognitive tests that included copying a figure of intersecting pentagons and then drawing the figure from memory. Patterns of drawing performance at the two time points were compared to the profile of other cognitive deficits.

RESULTS

A subgroup of four patients with frontal dysfunction showed marked improvement in drawings at a delay compared to copying. Prior studies have indicated that most patients have declines in drawing performance at a delay. The unusual pattern of better performance at a delay compared to an initial copy occurred in patients with frontal dysfunction. These patients' visuoconstructive deficit and subsequent improvement could be related to either a failure to disengage when a model is present, to memory consolidation with increased reliance on top-down processing in the delay condition, or to relative preservation of global versus local aspects of a stimulus in memory. The addition of a task to assess drawing after a delay to a standard clinical screening battery such as the Mini-Mental Status Examination (MMSE) provides the opportunity to evaluate this phenomenon that may be indicative of frontal-executive dysfunction.

Frontal defects contribute to the genesis of closing-in in Alzheimer's disease patients

Closing-in (CI) refers to copying drawings near to or superimposed on the original model, and is often observed in Alzheimer's disease (AD) patients. Contrasting hypotheses have been suggested to explain CI, but no prospective study has directly verified these interpretations. We evaluated the role of frontal/executive versus visuo-spatial impairments in a prospective sample of AD patients, and also explored whether different types of CI are related to specific neuropsychological tasks. We enrolled 64 AD patients who underwent copying tasks and an extensive neuropsychological assessment of visuo-spatial and visuo-constructional skills, frontal/executive abilities and anterograde memory. AD patients with CI showed more severe impairment on frontal/executive functions than AD patients without CI. Moreover, the tendency to produce copies superimposed on the model was selectively associated with poor inhibitory control for irrelevant responses. On this basis, we suggest that different CI phenomena could be ascribed to distinctive frontal/executive defects.

Inducing closing-in phenomenon in healthy young adults: the effect of dual task and stimulus complexity on drawing performance

Closing-in (CI) is the tendency to act very close to the model in tasks such as drawing, 3D construction, gesture imitation, or writing. Closing-in is observed in degenerative and focal brain diseases, but also in normally developing children. In the present paper, three experiments were conducted to evaluate whether CI can be triggered during a copying task in normal young adults by increasing stimulus complexity and attentional load. Participants were required to copy complex lines in one of three conditions: without interfering activities (baseline), during counting, or during execution of a 2-back short-term memory task. In Experiment 1, participants were required to reproduce horizontally aligned stimuli, starting from a dot placed below each stimulus and proceeding from left to right; in Experiment 2, stimuli were again horizontally aligned, but the starting dot was placed above each stimulus, and writing proceeded from right to left; in Experiment 3, stimuli were aligned vertically and copying proceeded in upward direction. Results from all experiments showed that when normal young adults are engaged in an attentional-demanding concurrent activity, they tend to approach to the model, whereas the effect of stimulus complexity disappeared with unusual writing direction (Experiments 2 and 3). These findings demonstrate that even in normal young adults, a reduction in available attentional resources can release an attraction toward the model.

Closing-in behavior in mild cognitive impairment: an executive deficit

This study explored Closing-in behavior (CIB), the tendency in figure copying to draw very close to or on top of the model, in mild cognitive impairment (MCI). The files of 154 people diagnosed with MCI were reviewed and CIB was identified in 21% of cases. Two approaches were used to explore CIB. First, we capitalized on the diverse cognitive profiles within MCI, subdividing the overall sample into people with and without memory deficits. The frequency of CIB was significantly higher in multidomain non-amnestic MCI than in multidomain amnestic MCI, suggesting that CIB is not associated with specific memory impairment. Second, we assessed the cognitive correlates of CIB, by selecting patients with MCI who completed a battery of executive, visuo-constructional and memory tasks. Sub-groups of patients with and without CIB showed a similar overall severity of cognitive decline and comparable performance in visuo-constructional and memory tasks, but those with CIB were slightly but significantly more impaired on executive function tasks. The study provides evidence against memory-based accounts of CIB, and supports recent suggestions that executive impairments are the dominant cognitive correlate of this clinical sign.

Current tests and trends in single-case neuropsychology

In this issue of Cortex, Crawford, Garthwaite and Ryan publish bayesian statistical tests that will enable researchers to take account of covariates when comparing single patients to control samples. In this article, we provide some context for this development, from an audit of the Cortex archives. We suggest that single-case research is alive and well, and more rigorous than ever, and that current practice has been shaped considerably by Crawford and colleagues' statistical refinements over the past 12 years. However, there is scope for further tightening and standardisation of statistical methods and reporting standards. The advantages offered by the new bayesian tests should promote the even wider use of appropriate statistical methods, with benefits for the validity of individual studies, and for cross-comparability in the single-case literature.