Assessment of Age-related Changes in Cognitive Functions Using EmoCogMeter, a Novel Tablet-computer Based Approach

Podsumowanie

We tested the usability of a tablet-computer-based application (EmoCogMeter) in investigating the effects of age on cognition. Results show an age-related cognitive decline, thereby proving the usability of our application. Findings underline the great clinical and practical potential of a tablet-based application for detection and monitoring of cognitive dysfunction.

Streszczenie

The main goal of this study was to assess the usability of a tablet-computer-based application (EmoCogMeter) in investigating the effects of age on cognitive functions across the lifespan in a sample of 378 healthy subjects (age range 18-89 years). Consistent with previous findings we found an age-related cognitive decline across a wide range of neuropsychological domains (memory, attention, executive functions), thereby proving the usability of our tablet-based application. Regardless of prior computer experience, subjects of all age groups were able to perform the tasks without instruction or feedback from an experimenter. Increased motivation and compliance proved to be beneficial for task performance, thereby potentially increasing the validity of the results. Our promising findings underline the great clinical and practical potential of a tablet-based application for detection and monitoring of cognitive dysfunction.

Wprowadzenie

Human aging is associated with cognitive decline in all domains, but might be particularly pronounced for functions associated with the prefrontal cortex and the medial temporal lobes, such as working memory (WM), episodic memory, and executive functions, (Bäckman et al.¹, Brehmer et al.², Shing et al.³, West⁴). Correspondingly, brain-imaging studies showed that volume reductions are most prominent in prefrontal and mediotemporal areas (Raz et al.^5,6) and that altered functioning within and between these regions might contribute to age-related cognitive changes (Sander et al.⁷, Park and Reuter-Lorenz⁸). Molecular imaging studies indicate that age-related dopamine losses might be powerful mediators of impairment in multiple cognitive tasks (Bäckman et al.^9,10; Erixon-Lindroth et al.¹¹, Volkow et al.¹²). There is considerable evidence that perceptive and cognitive competencies in old age might be enhanced by emotional stimuli. The tendency for older adults to perform better on positively valenced stimuli with regard to measures of attention, recognition, and emotional memory enhancement has been termed the age-related positivity effect (Charles et al.¹³, Mather and Knight¹⁴, Löckenhoff and Carstensen¹⁵, Grühn et al.¹⁶, Isaacowitz et al.¹⁷) and might reflect a difference in motivational goals as the end of life approaches (Carstensen and Löckenhoff¹⁸).

Neuropsychological testing of cognitive functions is usually conducted either by means of paper-and-pencil tests or computer-based tests on workstations, and might prove difficult when testing older subjects. Firstly, impaired motor skills might limit the use of paper-and-pencil tests and secondly, older subjects are often not familiar with keyboards, mouse pads, or other input devices applied during computer-based neuropsychological testing. As a result, older subjects often show poor motivation or compliance during neuropsychological testing, which might impair performance and decrease the validity of the findings. Furthermore, paper-and-pencil testing as well a computer-based testing on workstations requires permanent attendance of the experimenter for instruction and feedback as well as for documentation of results, which are then rarely transferred to a database and therefore only accessible to a very limited number of people. Thus, this "conventional" approach to neuropsychological testing ties up considerable human resources increases the probability of errors when transferring results, limits data access, and slows the workflow.

Our aim was to test a tablet-based application for the investigation of several neuropsychological domains. We used an iPad application as we hypothesized, that such a simple tool might be a quick and effective method to screen for and track cognitive deficits in clinical and outpatient settings. Regardless of age, subjects should be enabled to perform the tasks without instruction or feedback from an experimenter and should be able to complete the tests. Regardless of age, subjects should be enabled to perform the tasks without instruction or feedback from an experimenter. We hypothesized, that the touchpad would allow for a more intuitive use than other response devices (e.g. mouse pad or keyboard) particularly for older subjects, who are not familiar with computers. Heightened compliance and motivation for task performance might increase validity of results, while benefits for the experimenter should include a standardized and time saving testing procedure, a secure transfer of test results to a database and facilitation of data storage and analysis.

Protokół

1. Subjects

We recruited five hundred and forty-one psychologically and somatically healthy male and female subjects (age 44.47± 9.41; range 18-89 years; IQ 113.90±12.73). All subjects spoke German on a native speaker level. The study was carried out in accordance with the latest version of the Declaration of Helsinki and approved by the Institutional Review Board of the German Psychological Society. All subjects gave written informed consent before screening and were reimbursed for participation.

2. Study Design

The EmoCogMeter, an iPad-based application, includes 7 neuropsychological tests and was developed to investigate cognitive functions in several domains. Prior to each test, a short instruction and demonstration was displayed on the screen. There was no verbal instruction or feedback from the experimenter. Subjects needed approximately 25-30 min to complete the testing session.

1. Neuropsychological Tests
   1. Learning and memory
      1. Memory Span
         Present the participants with a series of digits and ask them to input the numbers immediately afterwards. Start with 2 digits and if participants are successful, give a longer list of numbers.
         1. End the task either after 5 min, or earlier, if subjects successfully recall 9 digits. Record the digit span and the number of total trials required to reach that level.
      2. Working Memory
         Have participants view sequences of positive, negative and neutral words and respond if a word is the same as the one presented two trials before.
         1. End the task after 5 min and record the number of correct responses (hits), false responses, and the mean latency of responses.
   2. Attention and concentration
      1. Selective Attention
         Apply a variant of the Stroop task and ask subjects to respond if the written color name corresponds to the color ink it was displayed in.
         1. End the task after 3 min and record the number of correct responses (hits), false responses, missed responses, and the mean latency of responses.
      2. Sustained Attention
         Use a task that includes a small working memory component. Present a circle consisting of small blue and yellow circles, illuminated in a pseudo-random order in the center of the screen.
         1. Instruct subjects to detect and respond to sequences of blue-yellow-yellow. End the task after 4 min and record the number of correct responses (hits), false responses, and missed responses.
   3. Executive Functions
      1. Trail Making Test B
         Probe task switching and require subjects to sequentially and alternatively connect 13 numbers and 12 letters on the screen. Do not display the connection if the subject made an error and do not continue the task before the correct connection is selected.
         1. End the task after 90 sec if it is not successfully completed until then. Record the total time required to complete the task.
      2. Tower of Hanoi
         Assess planning and the ability to achieve a goal through a series of intermediate steps. Use a version with three rods and four discs of subsequently smaller size.
         1. Inform subjects that they have to move the entire stack of discs to another rod by obeying the following rules: (1) Only one disk may be moved at a time. (2) Each move consists of taking the upper disk from one of the rods and sliding it onto another rod, on top of the other disks that may already be present on that rod. (3) No disk may be placed on top of a smaller disk.
         2. End the test if subjects fail to reach the goal after 4 min. Record the time needed to solve the task and the number of moves required for solution.
   4. Processing Speed
      Symbol Letter Modalities Test
      Present subjects with 9 letters and corresponding geometric symbols in the upper part of the screen. Display rows of letters in the lower part and instruct subjects to move the corresponding symbol under each letter as fast as possible.
      1. Record the number of correct responses (hits), false responses, missed responses and the mean latency of responses within the allowed time (90 sec).
2. Statistical analysis
   For the tests probing working memory, selective attention and sustained attention we defined an accuracy ratio ((hits- false)/ targets) x 100. All data were analyzed using multivariate analyses of variance (MANOVAs) with the between-subjects factors age group and gender. GreenhouseGeisser corrections were applied where appropriate. If MANOVAs revealed significant main or interaction effects, further statistical analyses were conducted using t-test comparisons.

Wyniki

Data from 19 subjects could not be recorded due to technical problems. All remaining subjects (N= 522) completed the tests and were clustered into 3 age groups (young: 18-30 years; middle-aged: 31-59 years; old: 60-89 years). Participants in these groups were matched according to gender and IQ resulting in a sample size of N= 378 (see Table 1). Performance for all neuropsychological tests in the 3 age groups is summarized in Table 2.

Learning and memory

Dyskusje

The main goal of this study was to assess the usability of a tablet-computer based application in investigating the effects of age on cognitive functions across lifespan. As hypothesized, subjects showed an age-related decline in most neuropsychological domains. For some cognitive functions, such as memory span, working memory accuracy, and selective attention, the decline appears to occur later in life, as it was only observed when comparing middle-aged and old subjects. Other cognitive functions, mainly response latenc...

Materiały

Name	Company	Catalog Number	Comments
Wortschatz-Test (WST)	http://www.testzentrale.de/programm/wortschatztest.html		Assessment of Intelligence
Berlin Affective Word List (BAWL)	Võ et al., 2009		Stimuli for working memory task
Predictive Analysis SoftWare, version 18.0	SPSS Inc.		Statistical Analysis
iPad	http://www.apple.com/de
EmoCogMeter	http://anem.charite.de/anem		Application for detection and monitoring of cognitive dysfunction