Background: A decline in cognitive test scores in elderly persons can signal the beginning of a descent into dementia or may indicate only a short-term cognitive disturbance. It would be clinically useful to distinguish between the two outcomes and to identify characteristics of each.
Methods: Four hundred thirty-seven community-dwelling elderly persons were given the Mini-Mental State Examination (MMSE) annually for an average of 7 years. A low score between baseline and final MMSE was identified. A low score 3 or more points lower than baseline score indicated cognitive decline. This decline was called persistent if the final MMSE score was also at least 3 points lower than baseline MMSE score; otherwise, the decline was considered transient.
Results: Twenty participants (4.6%) experienced a persistent cognitive decline, 67 participants (15.3%) experienced a transient cognitive decline. Presence of the apolipoprotein epsilon4 allele was significantly associated with persistent cognitive decline (age-adjusted odd ratio [OR] = 11.46, p < .0001) but not with transient cognitive decline (age-adjusted OR = 1.53, p = .219). Incorrect answers on the orientation part of the MMSE at the time of cognitive decline was associated with persistent decline compared to transient decline (age-adjusted OR = 3.58, p = .058).
Conclusions: Persistent cognitive decline is an infrequent occurrence in community-dwelling elderly persons. Presence of the epsilon4 allele and errors made by the subject on questions of orientation may be useful in determining whether a cognitive decline is likely to be persistent.