The document describes a study that tested whether performance on the Memory for Intentions Screening Test (MIST) could accurately predict conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD) within one year. Thirty participants without dementia were given neuropsychological tests including the MIST and re-tested one year later. Logistic regression found that only MIST performance significantly predicted conversion to AD, with 83% prediction success. A MIST cutoff score of 18 had 86% accuracy in distinguishing those who did and did not develop dementia within a year.

1. Memory for Intentions Screening Test
Abstract
Early detection of dementia may help slow the progression of the
illness and increase treatment efficacy. The Memory for Intentions Test
(MIST) was given to older individuals who did not exhibit dementia. They
were re-tested one year later to determine if first testing significantly
predicted those individuals that converted to a diagnosis of dementia. One
year after initial testing participants were administered the Dementia Rating
Scale-2 (DRS-2) and Alzheimer’s Disease Assessment Scale (ADAS-Cog).
A forward stepwise logistic regression analysis was conducted to predict
performance on the DRS-2 using the summary score from the MIST and
other measures. Prediction success overall was 75%. Neuropsychological
measures are easily obtained and well tolerated. The use of a
neuropsychological measure that accurately predicts conversion to
dementia would be helpful for early treatment and
management
Introduction
Early detection and intervention for people with dementia may help
slow the progression of the illness and increase treatment efficacy (Peterson
et al, 1999). There are several methods that have shown promise for the
early detection of cognitive decline. These include functional neuroimaging
techniques and analysis of biomarkers in cerebrospinal fluid (Kadir and
Nordberg, 2010; Wierenga and Bondi, 2007). However, these techniques
are expensive and not as yet readily available to the general public.
On the other hand, neuropsychological measures are easily obtained
and well tolerated. One area that appears particularly promising is
prospective memory (PM), the ability to remember to do something in the
future (Raskin et al., 2010). Preliminary evidence suggests that PM may be
sensitive to the onset of dementia, possibly reflecting decreased self-
initiation, attention switching of attention, or inhibition on memory tasks
because of early involvement of the frontal system in MCI and AD
(Huppert and Beardsall, 1993; Kazui et al, 2005; Jones et al, 2006; Troyer
& Murphy, 2007; Blanco-Campal et al, 2009; Costa et al, 2010 ).
To date, these studies have relied on a few PM tasks embedded in the
Rivermead Behavioral Memory Test (RBMT) (Huppert and Beardsall,
1993) or idiosyncratic experimental tasks (Troyer & Murphy, 2007). Jones
and colleagues (2006) found that event-based PM deficits are also sensitive
to predicting cognitive decline to AD and that PM deficits are more
accurate to predicting cognitive decline than retrospective memory deficits.
However, no study has used a standardized objective measure of PM
to examine this hypothesis. Previous research with a standardized measure
PM, the Memory for Intentions Test (MIST) has suggested that it is may be
effective in identifying PM deficits in patients with amnestic MCI (Troyer
& Murphy, 2007; Karantzoulis et al, 2009) and has been related to activities
of daily living in older adults (Woods et al., 2012).
In the present study we used the MIST to determine whether it could
be a quick and effective screening tool to predict conversion to AD in older
individuals with MCI.
David Correll, Damien DeCuir, Colin MacKichan, and Sarah Raskin
Psychology Department, Trinity College
Participants
Thirty participants between the ages of 20 and 80 were included. Older
participants were recruited from a nearby senior center and a memory
disorders clinic. The exclusion criteria consisted of a current dementia
diagnosis (ruled out by the Mini Mental State Examination (MMSE,
Folstein et al, 2000) and medical record review), history of neurological or
psychiatric illness, significant cardiac or pulmonary illness, significant
hearing or visual loss, a Beck Depression Inventory-II (BDI-II) (Beck,
Steer & Brown, 1996) score >15, a Beck Anxiety Inventory (Beck & Steer,
1993) > 25 or a Global Deterioration Scale (GDS) score >10. The Trinity
College Institutional Review Board approved the study.
Neuropsychological Measures
Neuropsychological measures included the Tower of Hanoi (Sanzen
Neuropsychological Assessment Tests), Controlled Oral Word Association
Test (Loonstra et al., 2001), Hopkins Verbal Learning Test (HVLT; Brandt
& Benedict, 2001), and the Logical Memory and Visual Paired Associates
subtests from the Weschler Memory Scale- Revised (WMS-IV; Wechsler,
2009). Prospective memory was assessed using the Memory for Intentions
Screening Test (MIST, Raskin et al., 2010) and the Comprehensive
Assessment of Prospective Memory (CAPM; Waugh, 1999) self report
survey.
All participants received all neuropsychological measures in one testing
session of approximately 2 hours. One year after initial testing participants
were administered the Dementia Rating Scale-2 (DRS-2) (Mattis, 1988)
and Alzheimer’s Disease Assessment Scale (ADAS-Cog) (Rosen et al.,
1984) to determine if any participants have converted to Alzheimer’s
disease.
Results
The only neuropsychological measure that correlated with the MIST
was the Tower of Hanoi. A forward stepwise logistic regression analysis
was conducted to predict score on the DRS using variables found to be
significant in the correlational analysis: the summary score of prospective
memory ability from the MIST, the Tower of Hanoi and Hopkins Verbal
Learning Test. A binary variable was created for the DRS with a cutoff of
129. Neuropsychological variables were entered in block one and summary
score from the MIST was entered in block two. A test of the model was
statistically significant, indicating that the predictor as a set reliably
distinguished between individuals having a total DRS of less than 129 with
those having a higher score. Prediction success overall was 83%. The Wald
criterion demonstrated that Total on the MIST made a significant
contribution to prediction (p _ .008). The remaining tested variables were
not significant predictors. Subsequent analysis revealed that a MIST
Summary Score cutoff of 18 produced the strongest (86%) accuracy for
grouping older individuals into those likely to develop dementia and those
not on the cusp of developing dementia.
Discussion
Based on these findings, MIST performance appears to be sensitive to
age-related changes in PM. MIST appears to be related to both medication
adherence and self-report in a healthy population. It was also shown that
age, even in young-old individuals, appears to be related to modest deficits
in time-based prospective memory. The study also reaffirmed former
conclusions reached. It provided additional support for executive deficits
underlying poor performance. The study also further supported the assertion
that prospective memory performance may be an early indicator of cognitive
decline with age.
However effective the study was, a few limitations existed. It did not
comprehensively determine neuropsychological status to ensure all were
cognitively intact at first testing. Due to the fact that all event-based tasks
have cues and items related, the attentional control demands were lowered.
It is also possible that there exist ceiling effects in young participants. This
study only accounted for young and old groups, and did not account for the
in-between age group.
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Figure 1. Effect of time delay by
age on the MIST.
Figure 2. Effect of Cue Type by Age
on the MIST
Figure 3. Error Scores by Age on
the MIST
Figure 4. 24-hour Delay Task
(naturalistic task) on the MIST
Figure 6. One year follow-up of
oldest group by MIST total score