Review: Impairment of Instrumental ADL in Mild Cognitive Impairment

The paper reviewed here is ‘Impairment of Instrumental Activities of Daily Living in Patients with Mild Cognitive Impairment’ by Ahn and colleagues and freely available here. In the conclusion, the authors write that

‘The patients with MCI showed impairments in the ability to perform complex ADL in comparison to healthy controls. IADLS’s related to memory and frontal/executive functioning were particularly affected in MCI‘

The study was carried out in South Korea. The researchers have selected

• 66 subjects with MCI (mean age 70.76 years)
• 61 health controls (mean age 64 years)

Controls were recruited by advertisement whilst the recruitment method for the MCI group was unclear. The criterion used for MCI are clearly stipulated and include

• Cognitive performance of 1.5 SD below the age and education norm in one or more of the following domains: memory, language, visuoconstruction, and frontal/executive function
• Cognitive decline by self and/or informant reporting

The subjects were also administered a battery of neuropsychological tests including

• Digit span forwards and backwards
• Korean-Boston Naming Test
• Rey-Kim Complex Figure TEST
• Clock Drawing TEST
• Contrasting Program, Go-no-go Test

amongst others. The study focused on the performance of MCI subjects on two measures of functioning – The Seoul Instrumental Activities of Daily Living (SIADL) and the Seoul Activities of Daily Living. About the SIADL, the researchers write that it assesses a number of functions and that

‘These include the ability to prepare a balanced meal, remember appointments, keep financial records, remember to take medication and so on‘

and is composed of 15 items. The primary research questions seems to be fairly straightforward – is there a difference between the MCI and control groups on the ADL’s? The researchers used a multivariate logistical regression analysis to investigate this relationship. They also wanted to find the optimal cut-off point for MCI and used a ROC curve for this purpose.

The MCI group scored significantly higher on the S-IADL than the control group (4.47 v 1.44) and this difference remained after controlling for variables including age. The S-IADL discriminated well between the control and MCI groups with a sensitivity and specificity of 82%. The researchers write that the

‘MCI patients showed significantly more impairment in the areas of ‘using the telephone’, ‘preparing meals’, ‘taking medication’, ‘managing belongings’, ‘keeping appointment’, ‘talking about recent events’, and ‘leisure/hobbies’ than normal elderly controls‘

Conclusions

Although these results are extremely encouraging I’m not sure if they generalise to the english version of the IADL and maybe another study with the English version needs to be undertaken. However the MCI group have a mean age of just over 70 years of age and again it would be unclear if this would generalise to a group in their early 60’s or late 50’s although the correction for age indicated that a significant difference between the groups remained.

There is an interesting question here which is about the precise nature of the relationship between the memory and executive components of the neuropsychological test battery and the performance on the IADL. Making a telephone call presumably involves a number of cognitive functions – motor cognition, working memory, episodic memory, auditory processing, attention and executive functions at the very least. Therefore if we could see which areas of the brain light up, during a telephone conversation (i.e fMRI) on the basis of the above we might expect to see the corresponding areas in the relevant order although it is never that simple. It might be expected that if some tasks require more cognitive functions they would be more susceptible to the effects of MCI – thus there might be a  hierarchy (although the individual tasks will vary in complexity).

More importantly from this study, this has implications for the workplace. If people have MCI and are working then this study suggests that it may interfere with a number of tasks around the workplace. If that is the case, then it would mean that assistive technologies may be useful. Furthermore the need for assistive technologies could be estimated from performance on a paper and pen test given the effective discrimination between the MCI and control groups (as MCI was assessed using the neuropsychological tests discussed above). It will be interesting to see if this study is replicated using an English version of the IADL.

 

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