Is terminal drop pervasive or specific?

The terminal drop hypothesis states that death is preceded by a decrease in cognitive functioning over an approximately five-year period prior to death (Riegel & Riegel, 1972); there is some disagreement as to whether this decrease is pervasive or restricted to specific abilities. The present study assessed the relationship between distance from death and tests of vocabulary, numerical facility, and perceptual speed for 97 subjects who had died within seven years of testing. Only vocabulary scores for those who died at age 70 or less and within two years of testing were affected by terminal drop. An additional analysis comparing the performance of the deceased subjects with a still-living sample matched for age, gender, and education produced nonsignificant results but a trend consistent with the initial analyses. Thus the terminal drop phenomenon may be limited to abilities that typically are relatively unaffected by age, such as vocabulary or other verbal abilities. Furthermore, the effects may be restricted to a time period much closer to death than had been originally proposed.