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====== Cogstate ======

The [[http://www.cogstate.com|Cogstate]] is a battery of computerized cognitive tests used in [[start|Lifelines]] to broadly assess cognitive functioning of participants ([[sections|section]]: [[mental health]]). The test battery was performed in ~68,000 able participants aged 13 years and older during [[2A Visit 1]], and is used again in the ongoing assessment [[3A]].\\
The Cogstate is used in conjunction with other cognition tests in Lifelines, i.e. the [[Ruff Figural Fluency Test|RFFT]] and the [[Mini Mental State Examination|MMSE]]. Raw data of the Cogstate was used to calculate the [[Cogstate Speed Composite (CSC)]].

===== Protocol =====

Lifelines uses the brief battery of Cogstate tests. Measuring different cognitive function domains which were completed in the following order: 
  - Detection task (psychomotor function / speed of processing) (2 min)
  - Identification task (visual attention/vigilance) (2 min) 
  - One back (working memory) (2 min) 
  - One Card Learning task (visual learning & memory) (5 min)
NB: The Groton Maze Learning Task, which is part of the full Cogstate battery, was not used in Lifelines.

All subtests are based on playing card formats, with little reliance on assessment of verbal abilities. The Brief Battery can be administered un-supervised. \\
Written instructions are presented on the screen. Responses are made on a computer keyboard represented on the screen, with responses by using the “k” key for yes and “d” key for no. 
Outcome measures are: 
  - number of errors/correct responses
  - reaction time 
The participant should be able to use a computer keyboard or mouse with one hand and should be able to see the computer screen (i.e. normal vision observation). If participants use reading glasses, they are recommended to use them during this task. 

{{:cogstate.png?200|}}

{{ :cogstate_sop_in_dutch.pdf |}}

===== Validation =====

__Content validity:__ Content validity of the Cogstate can be considered good because it includes a broad range of cognitive functioning domains. The Cogstate testing method has been validated in international peer-reviewed journals. It targets a wide range of cognitive domains, including simple reaction time, attention, executive function and social-emotional cognition. The tests are designed to maximize the signal and minimize the noise from cognitive recordings taken in research trials. They have a proven ability to detect both improvement and decline in cognition. 

__Criterion/construct validity:__ No gold standard is currently available to measure cognitive functioning.  However, The [[Mini Mental State Examination|MMSE]] is a widely used screening instrument for cognitive function and measures global cognitive functioning ((Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975). "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. Journal of Psychiatric Research, 12(3), 189-198)). Based on a case control study including 21 subjects with mild cognitive impairment and 98 healthy controls (age > 60 year), the Cogstate had a sensitivity of 78% and specificity of 90%. This was much higher compared to the Mini Mental State examination (MMSE) (sensitivity: 44%, specificity: 69%).  The study also investigated the sensitivity and specificity of the Hopkins Verbal Learning Test (HVLT) and this test had a slightly better sensitivity (79%) and specificity (95%) compared to the Cogstate ((de Jager, C. A., Schrijnemaekers, A. C., Honey, T. E., & Budge, M. M. (2009). Detection of MCI in the clinic: Evaluation of the sensitivity and specificity of a computerised test battery, the hopkins verbal learning test and the MMSE. Age and Ageing, 38(4), 455-460)). However, the HVLT is based on a paper-and-pencil test, which needs to be conducted under guidance of an assistant which may influence sensitivity and specificity. In this case-control study, participants performing the Cogstate were supervised by one of three psychologists through a practice session on the Cogstate (to maximize good performance), followed by the test battery with minimal supervision/assistance. 

The __test-retest reliability__ of different Cogstate subtests has been described in various studies ((Darby, D., Maruff, P., Collie, A., & McStephen, M. (2002). Mild cognitive impairment can be detected by multiple assessments in a single day. Neurology, 59(7), 1042-1046)) ((Lim, Y. Y., Jaeger, J., Harrington, K., Ashwood, T., Ellis, K. A., Stoffler, A., . . . Maruff, P. (2013). Three-month stability of the Cogstate brief battery in healthy older adults, mild cognitive impairment, and alzheimer's disease: Results from the australian imaging, biomarkers, and lifestyle-rate of change substudy (AIBL-ROCS). Archives of Clinical Neuropsychology : The Official Journal of the National Academy of Neuropsychologists, 28(4), 320-330)) ((Falleti, M. G., Maruff, P., Collie, A., & Darby, D. G. (2006). Practice effects associated with the repeated assessment of cognitive function using the Cogstate battery at 10-minute, one week and one month test-retest intervals. Journal of Clinical and Experimental Neuropsychology, 28(7), 1095-1112)). 

__Responsiveness__ of the instrument has been assessed by measuring decline in cognitive performance of patients with mild Alzheimer’s Disease on the International Shopping List Test (ISLT); a subtest of the Cogstate((Lim, Y. Y., Pietrzak, R. H., Snyder, P. J., Darby, D., & Maruff, P. (2012). Preliminary data on the effect of culture on the assessment of alzheimer's disease-related verbal memory impairment with the international shopping list test. Archives of Clinical Neuropsychology : The Official Journal of the National Academy of Neuropsychologists, 27(2), 136-147)). Results show that compared to controls, patients with Alzheimer’s Disease show deterioration in verbal memory over a period of one year. We would expect similar results on all other subtests of the CogState suggesting that the Cogstate is sensitive to changes in cognitive functioning in persons with Alzheimer’s disease. A longer period of follow-up would be needed to be able to say something about responsiveness among the general population (i.e. persons without cognitive impairments). 

__Cogstate in Lifelines__: correlations between the Cogstate and [[Ruff Figural Fluency Test|RFFT]] scores are described in a paper by Kuiper et al. ((Kuiper, J.S., Oude Voshaar, R.C., Verhoeven, F.E.A., Zuidema, S.U., and Smidt, N. (2017). Comparison of cognitive functioning as measured by the Ruff Figural Fluency Test and the Cogstate computerized battery within the LifeLines Cohort Study. BMC Psychol. 5, 15))
\\


===== Versions =====
The Cogstate brief battery was measured during [[2A Visit 1]] and [[3A Visit 1]]. During the third assessment ([[3A]]) the test was redesigned by the Cogstate research group. The test and protocol stayed the same for the participants, however more variables were measured during the test.\\
In [[2A Visit 1]] around 92.000 participants had valid Cogstate results. In [[3A Visit 1]] around 15.000 participants had valid results on the original brief battery and 24.000 on the redesigned version. At this moment assessment 3A is still going on, meaning the redesigned version number will increase overtime.  

=== Variable suffixes ===
  * To reflect the difference between the Cogstate variables and the redesigned Cogstate variables, please pay attention to how the variables are written in the column named 'Code' in the variable table.
  * Most variables listed in the below table are test specific. For this reason a '_XX' will be added to the variable name in data releases. Due to a database variable continuity the '_XX' suffixes per test are different from the order in which the tasks were performed. The suffixes are as followed:


| **Task in order of completion**  |  **Suffix**  |
| Detection task                   |      _02     |
| Identification task              |      _01     |
| One back task                    |      _04     |
| One Card Learning task           |      _03     |

\\
=== Completion criteria 2A ===
the Cogstate variables are, just as all other data, presented 'as-is'. Meaning that all available data will be present. The Cogstate research group has a completion criteria for all participants. This criteria determines when according to their standards the test was valid. If a participant scored too low on one of the following variables the results of the test is considered invalid.
\\
| **Task in order of completion**  | **cogstate_stimuli_all_m_1** | **cogstate_hitrate_all_m_1** |
| Detection task                   |             < 27             |             < 80%            |
| Identification task              |             < 23             |             < 80%            |
| One back task                    |             < 24             |             < 70%            |
| One Card Learning task           |             < 60             |             < 50%            |

\\
===== Variables =====

| **Label English**                                                                                                                                                               | **Code**                        | **Variable**  | **Assessment**  | **Age**  |
| Session passed completion criteria?                                                                              | cogstate_completion_all_m_2       | SessionCompletionPass           | [[3A Visit 1]]  | 13+      |
| Test completion criteria                                                                                                                   | cogstate_completion_all_m_1_XX       | COMPLETION         | [[3A Visit 1]]  | 13+      |
| Test performance criteria                                                                                                                          | cogstate_completion_all_m_2_XX       | TestCompletionPass           | [[3A Visit 1]]  | 13+      |
| Session passed performance criteria?                                                                                 | cogstate_performance_all_m_2       | SessionPerformancePass         | [[3A Visit 1]]  | 13+      |
| Test performance criteria                                                                                                                          | cogstate_performance_all_m_2_XX       | TestPerformancePass           | [[3A Visit 1]]  | 13+      |
| Test integrity criteria                                                                                             | cogstate_integrity_all_m_1_XX       | INTEGRITY           | [[3A Visit 1]]  | 13+      |
| Session passed integrity criteria?                                                                                 | cogstate_integrity_all_m_2       | SessionIntegrityPass           | [[3A Visit 1]]  | 13+      |
| Test integrity criteria <sup> i </sup>                                                                                 | cogstate_integrity_all_m_2_XX       | TestIntegrityPass           | [[3A Visit 1]]  | 13+      |
| The total duration of the current session (ms)                                                                                 | cogstate_durationtotal_all_m_2       | SessionDuration          | [[3A Visit 1]]  | 13+      |
| The total time (ms) from test start until the end of the test                                                                                 | cogstate_duration_all_m_2_XX       | TestDuration           | [[3A Visit 1]]  | 13+      |
| The score on the primary outcome for this test <sup> ii </sup>                                                                                 | cogstate_primaryoutcome_all_m_2_XX       | PrimaryOutcome           | [[3A Visit 1]]  | 13+      |
| The score on the alternate outcome for this test <sup> iii </sup>                                                                                 | cogstate_outcomealt_all_m_2_XX       | AlternateOutcome           | [[3A Visit 1]]  | 13+      |
| Speed measure - mean of reaction time for correct responses                                                                                                                     | cogstate_speed_all_m_1_XX          | LMNUNTRANS    | [[2A Visit 1]] \\ [[3A Visit 1]]  | 13+      |
| Speed measure - standard deviation of the log10 transformed reaction time for correct responses                                                                                 | cogstate_logstdev_all_m_1_XX       | LSD           | [[2A Visit 1]] \\ [[3A Visit 1]]  | 13+      |
| Raw reaction time of performance (ms)                                                                                 | cogstate_speed_all_m_2_XX       | RawReactionTime           | [[3A Visit 1]]  | 13+      |
| Speed measure - mean of the log10 transformed reaction time for correct responses                                                                                               | cogstate_speedtransf_all_m_1_XX    | LMNTRANS      | [[2A Visit 1]] \\ [[3A Visit 1]]  | 13+      |
| Reaction time of performance (log10 ms)                                                                                  | cogstate_speedtransf_all_m_2_XX       | ReactionTime           | [[3A Visit 1]]  | 13+      |
| Raw consistency of performance (ms)                                                                                 | cogstate_consistency_m_2_XX       | RawRTVariability           | [[3A Visit 1]]  | 13+      |
| Consistency of performance (log10 ms)                                                                                 | cogstate_consistencytransf_m_2_XX       | RTVariability           | [[3A Visit 1]]  | 13+      |
| Raw accuracy of performance                                                                                                                         | cogstate_accuracy_all_m_2_XX       | RawAccuracy           | [[3A Visit 1]]  | 13+      |
| Accuracy measure - arcsine square root transformed - hitrate (correct responses divided by total responses (total includes TPos, TNeg, FPos, FNeg, anticipations and max outs)                                                       | cogstate_hitratetransf_all_m_1_XX  | ACCTRANS      | [[2A Visit 1]] \\ [[3A Visit 1]]  | 13+      |
| Accuracy measure - hit rate (correct responses divided by total responses (total includes TPos, TNeg, FPos, FNeg, anticipations and max outs)                                                                                        | cogstate_hitrate_all_m_1_XX        | ACCUNTRANS    | [[2A Visit 1]] \\ [[3A Visit 1]]  | 13+      |
| Accuracy of performance (arcsine square root proportion correct)                                                                                 | cogstate_accuracytransf_all_m_2_XX       | Accuracy           | [[3A Visit 1]]  | 13+      |
| Total presentations or trials.                                                                                                                                              | cogstate_presentations_all_m_1_XX  | PRESNT        | [[2A Visit 1]] \\ [[3A Visit 1]]  | 13+      |
| Total correct responses                                                                                                                                                         | cogstate_correct_all_m_1_XX        | COR           | [[2A Visit 1]] \\ [[3A Visit 1]]  | 13+      |
| Number of correct responses                                                                                         | cogstate_correct_all_m_2_XX       | TotalCorrect           | [[3A Visit 1]]  | 13+      |
| Number of correct responses after pant responses have been excluded                                                                                 | cogstate_correctexclpant_all_m_2_XX       | TotalCorrectExclPant           | [[3A Visit 1]]  | 13+      |
| Total error responses (includes FPos, FNeg, anticipations and max outs).                                                                                                        | cogstate_errors_all_m_1_XX         | ERR           | [[2A Visit 1]] \\ [[3A Visit 1]]  | 13+      |
| Number of errors                                                                                                                         | cogstate_errors_all_m_2_XX       | TotalErrors           | [[3A Visit 1]]  | 13+   |
| Number of legal errors                                                                                                                         | cogstate_legalerrors_all_m_2_XX       | LegalErrors           | [[3A Visit 1]]  | 13+      |
| Number of errors that break the rules of the test                                                                                 | cogstate_rulebreak_all_m_2_XX       | RuleBreakErrors           | [[3A Visit 1]]  | 13+      |
| Number of anticipatory responses                                                                                 | cogstate_anticipatory_all_m_2_XX       | TotalAnticipatory           | [[3A Visit 1]]  | 13+      |
| Number of post responses                                                                                                                         | cogstate_postresponses_all_m_2_XX       | TotalPost          | [[3A Visit 1]]  | 13+      |
| Number of maxout responses <sup> iv </sup>                                                                                 | cogstate_maxout_all_m_2_XX       | TotalMaxOut           | [[3A Visit 1]]  | 13+      |
| number of responses (correct + errors)                                                                                 | cogstate_responses_all_m_2_XX       | TotalResponses           | [[3A Visit 1]]  | 13+      |
| CPAL and ISLT specific - "Stimuli". For CPAL is total filled markers, and for ISLT is total words in the presented list.                                                                                                                                | cogstate_stimuli_all_m_1_XX        | STI           | [[2A Visit 1]] \\ [[3A Visit 1]]  | 13+      |
| Number of stimuli                                                                                                                         | cogstate_stimuli_all_m_2_XX       | TotalTrials         | [[3A Visit 1]]  | 13+   |
| Standardized z-score for the primary outcome measure                                                                                 | cogstate_zscore_all_m_2_XX       | StandardScoreZ           | [[3A Visit 1]]  | 13+      |
| Standardized t-score for the primary outcome measure                                                                                 | cogstate_tscore_all_m_2_XX       | StandardScoreT           | [[3A Visit 1]]  | 13+      |
| standardized z-score for the alternate outcome measure <sup> iii </sup>                                                                                 | cogstate_zscorealt_all_m_2_XX       | AltstandardScoreZ           | [[3A Visit 1]]  | 13+      |
| Standardized t-score for the alternate outcome measure <sup> iii </sup>                                                                                 | cogstate_tscorealt_all_m_2_XX       | AltstandardScoreT           | [[3A Visit 1]]  | 13+      |
| The score on the psychomotor function/attention composite, incorporating the primary outcome measure for the detection and identification tests, relative to age-matched normative data                                         | cogstate_psyattscore_all_m_2_XX       | PsyAttStdScr           | [[3A Visit 1]]  | 13+      |
| The score on the learning/working memory composite, incorporating the primary outcome measures for the one card learning and one back tests (accuracy), relative to age-matched normative data                                         | cogstate_learnwmscore_all_m_2_XX       | LearnWMStdScr           | [[3A Visit 1]]  | 13+      |
| The score on the learning/working memory composite, incorporating the primary outcome measure for the ocl test (accuracy) and the alternate outcome measure for the onb test (reaction time), relative to age-matched normative data                                                                                                                         | cogstate_scorealt_all_m_2_XX       | AltLearnWMStdScr           | [[3A Visit 1]]  | 13+      |
| Left- or righthanded                                                                                                        | cogstate_handedness_all_q_1       | HAND           | [[3A Visit 1]]  | 13+      |
<sup> i </sup> Only calculated on test _02 (Identification task) \\
<sup> ii </sup> Primary outcome is reaction time (Detection/Identification task) or accuracy (One Back/One Card Learning task) \\
<sup> iii </sup> Only calculated on test _04 (One Back task) \\
<sup> iv </sup> Calculated on tests _01,_02 and _04 (Detection, One back and One Card Learning task)
\\