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Although Alzheimer’s Disease (AD) is usually diagnosed above the age of 70, Mild Cognitive Impairment (MCI) can be detected from as young as age 50. The online Cognitive Function Test aims to provide a tool for individuals to self-assess their level of MCI in the cognitive domains that predict AD. This article provides an overview of the 3 cognitive domains assessed – episodic memory, executive function and processing speed; and the criteria for computeriation of the test.

The detectable, preclinical phase of Alzheimer’s Disease (AD) presents as mild cognitive impairment (MCI)1. AD is normally diagnosed above the age of 70, but MCI can be detected from as young as age 50 2, 3. Detecting MCI is one way of assessing an individual’s risk of later developing AD 4.

Tests for cognitive function have existed in paper and pencil form for many years and are primarily licensed by specialist psychometric assessment providers to research establishments or for employer use. They are not generally available to the public. Furthermore we know that individuals aged 50 to 70 may be reluctant to approach their GP with concerns about memory problemsa. Therefore there is currently no easy provision for individuals wishing to assess whether they have MCI.

The Cognitive Function Test (CFT) aims to provide individuals with a tool to self-assess their level of MCI in the cognitive domains that predict AD. It is online and free to anyone with internet access aged 50 or above. It is suggested that those who score poorly in the CFT might take a homocysteine test and if necessary embark upon diet and lifestyle changes and reduce their homocysteine level, in order to reduce the risk of further memory decline.

Cognitive Domains Tested

Cognitive domains that are deemed particularly indicative of MCI as a pre-AD condition are: episodic memory, executive function and processing speed.

Episodic memory is about cognitive processes involved in the acquisition, storage and retrieval of new information. It involves conscious recollection of information learned within a context. The term "learning" refers to the acquisition of skills and knowledge while the term "memory" refers to the persistence of this learning over time and/or the facility with which one is able to spontaneously recall the information following a delay. Episodic memory can be verbal, as in remembering a conversation or a list of grocery items, or nonverbal, as in imagining a place one visited or a picture one saw a week ago’6. Episodic memory impairment is the most common initial symptom of MCI4. The tests most sensitive to early AD are delayed recall memory measures7. The CFT offers a visual delayed recall test. An initial learning phase in which the respondent identifies common items is followed by other tests designed to fully engage the attention of the respondent. Subsequently, respondents are tested on combined cued recall and spatial location memory.

Executive function is the capacity to plan, organize, and monitor the execution of behaviours that are strategically directed in a goal-oriented manner6. The CFT includes a symbol matching test which, whilst it requires attention and processing speed, reflects executive function by requiring a judgment to choose the correct answer in a more complex way than a processing speed test.

Processing speed is the amount of time it takes to process a set amount of information, it reflects mental efficiency. The CFT uses the well established PCS/LCS test developed by Professor Timothy Salthouse at the University of Virginia to assess processing speed.

The CFT also includes a separate test to assess computer competence. This is a new and simple test in which respondents are asked to click 20 items as quickly as they can and a click speed is derived.

Computerisation of the Cognitive Function Test

Computerisation of cognitive function tests for online use requires that four criteria be met:

Intuitive testing format. Respondent processing of on-screen instructions is variable and, in the absence of a face-to-face assessor, real time advice cannot be offered. Therefore tests must be entirely intuitive to the respondent.

Simple response mechanisms independent of computer competence and network speed. This precludes bandwidth demanding graphics and respondent actions such as voice response, typing and complex mouse use. It indicates the use of click buttons where possible and careful use of limited option dropdown menus.

Automatic and instant assessment mechanisms. Volume and speed precludes the use of assessor judgment of responses and requires instant calculation, in line with the online users expectation of immediate results.

Suitable level of visual complexity with font and patterns being large enough to read easily. To be in line with established paper and pencil tests. This is counterbalanced by the need to provide for smaller screen sizes.

Piloting the Cognitive Function Test

Paper and pencil tests for mild cognitive impairment (MCI) related domains are well established, however online testing required the development of an intuitive testing format, a mechanism to assess computer competence and network speed-independent response mechanisms, automatic and instant scoring and feedback mechanisms.

Thus it was necessary to compare the Cognitive Function Test (CFT) with established paper and pencil tests for MCI. A pilot study was undertaken and the results of this are described in a paper pending peer review.

The correlation between the CFT and paper and pencil tests was found to be highly significant with r2 at over 0.75, and each of the 3 components was also positively correlated with its counterpart.

MCI
A full description of this pilot and the analysis is in the process of being submitted for peer review and publication.

References

Elias M F, Beiser A, Wolf P A et al. (2000) The preclinical phase of Alzheimer's disease: a 22-year prospective study of the Framingham Cohort. Arch Neurol 2000;57:808-813.

D, Smith A. (2002) Imaging the progression of Alzheimer pathology through the brain. PNAS 99. p4135-4137.

Ohm T G, Muller H, Braak H, Bohl J (1995) Close-meshed prevalence rates of different stages as a tool to uncover the rate of Alzheimer's disease-related neurofibrillary changes. Neuroscience 64: p209-217.

De Jager C A, Schrinjemaekers A-C M, Honey T E M, 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.

Smith D A, Smith M S, de Jager C A, Whitbread P, Johnston C, Agacinski G, Oulhaj A, Bradley K M, Jacoby R, Refsum H. (2010) Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial. PLoS ONE 5(9): e12244

NIH Toolbox Initiative. Assessment of Neurological and Behavioural Function http://www.nihtoolbox.org/WebPart%20Pages/Cognition.aspx [accessed 25 March 2011].

Mohs R C (2000) Neuropsychological Assessment of Patients with Alzheimer's Disease Neuropsychopharmacology The 4th Generation of Progress. [Based on February 2011 short online survey (n=100) 33% had concerns about their memory, yet only 1% had discussed this with their GP. Reasons cited included the assumption that memory decline was a normal part of aging (51.4%), not thinking their case was serious enough (50%) and lack of treatment available (12%)].