SMC and MCI or Dementia
The significance of SMC would be greatly enhanced if SMC, particularly in older
adults, portend later clinical diagnoses of cognitive impairment, such as MCI or
dementia. Indeed, the literature shows that SMC quite consistently predict later
cognitive impairment or dementia. A large study of nearly 2000 participants found
that SMC at baseline, as assessed byfive specific questions about a change in
memory in the past 10–20 years, were associated with incident dementia during
follow-up 5 years later, after adjusting for age, baseline scores, and depressive
symptoms (Wang et al. 2004 ). In Fig.13.4, Kaplan-Meier survival estimates for the
probabilities of being dementia free are presented. Subjects who reported subjective
memory deterioration but were cognitively normal at baseline were less likely to be
dementia free than those who reported no subjective memory deterioration.
Additionally, two reports from the AMSTEL study reveal an association between
baseline SMC and future dementia. In thefirst report, over 300 healthy adults aged
65 – 84 years were seen at baseline and 3-year follow-up. SMC were assessed by 10
questions about specific memory problems. Objective cognitive function was
assessed annually, and dementia diagnosis was made by clinical criteria. SMC were
an independent predictor of dementia at 3-year follow-up (Schmand, et al. 1996 ).
Thisfinding was replicated in a much larger sample from the AMSTEL study that
included over 2000 participants assessed at baseline and 4-year follow-up
(Schmand et al. 1997 ).
There is some indication that baseline cognitive status influences the ability of
SMC to predict dementia, though data are conflicting. In a study of nearly 5000
older adults seen at baseline and 3 years later, SMC were associated with incident
Fig. 13.4 Kaplan-Meier
survival estimates for the
probabilities of being
dementia free. Subjects who
reported subjective memory
deterioration (SMD) but
scored normal on the
Cognitive Ability Screening
Instrument at baseline were
less likely to be dementia free
than those who reported no
SMD. Reproduced with the
permission from Wang et al.
( 2004 )
13 Subjective Memory Complaints and Objective Memory Performance 291