Impaired ability to conduct daily activities is a diagnostic criterion
for dementia and a determinant of healthcare services utilization and
caregiver burden. What predicts decline in instrumental activities of
daily living (IADLs) is not well understood. This study examined measures
of episodic memory, executive function, and MRI brain volumes in relation
to baseline IADLs and as predictors of rate of IADL change. Participants
were 124 elderly persons with cognitive function between normal and
moderate dementia both with and without significant small vessel
cerebrovascular disease. Random effects modeling showed that baseline
memory and executive function (EXEC) were associated with baseline IADL
scores, but only EXEC was independently associated with rate of change in
IADLs. Whereas hippocampal and cortical gray matter volumes were
significantly associated with baseline IADL scores, only hippocampal
volume was associated with IADL change. In a model including cognitive and
neuroimaging predictors, only EXEC independently predicted rate of decline
in IADL scores. These findings indicate that greater executive dysfunction
at initial assessment is associated with more rapid decline in IADLs.
Perhaps executive function is particularly important with respect to
maintaining IADLs. Alternatively, executive dysfunction may be a sentinel
event indicating widespread cortical involvement and poor prognosis.
(JINS, 2007, 13, 747–757.)