One-year longitudinal investigation of eyeblink classical conditioning and cognitive and behavioral tests in adults with down's syndrome

Thirty-three adults with Down's syndrome (DS) originally tested by Woodruff-Pak, Papka, and Simon (1994) were retested approximately one year after initial testing as part of an ongoing longitudinal study. Subjects were tested in eyeblink classical conditioning (EBCC) and other neuropsychological tests. Adults with DS improved in EBCC over a 13-month period, but showed stability on other cognitive and behavioral tests. Age differences were found in EBCC but not other measures. Adults with DS aged 19-30 years performed significantly better in EBCC than adults with DS aged 46-65 years. Adults with DS aged 31-45 years did not show significantly different EBCC performance than subjects in older and younger age groups. the impaired EBCC performance of older adults with DS may be due to the presumed disruption of the hippocampal cholinergic system, which is an aspect of the Alzheimer-like neuropathology developing in adults with DS after the age of 35. the results further support the sensitivity of EBCC to Alzheimer-like neuropathology in older adults with DS.