Rates of hippocampal atrophy correlate with change in clinical status in aging and AD

Background: The cognitive continuum in the elderly population can be concep tually divided into those who are functioning normally (control subjects), those with a mild cognitive impairment (MCI), and those with probable AD. O bjectives: To test the hypothesis that the annualized rates of hippocampal atrophy differ as a function of both baseline and change in clinical group membership (control, MCI, or AD). Methods: The authors identified 129 subje cts from the Mayo Clinic AD Research Center/AD Patient Registry who met est ablished criteria for normal control subjects, MCI, or Probable AD, both at entry and at the time of a subsequent clinical follow-up evaluation 3 +/- 1 years later. Each subject underwent an MRI examination of the head at the time of the initial assessment and at follow-up clinical assessment; the a nnualized percentage change in hippocampal volume was computed. Subjects wh o were classified as controls or patients with MCI at baseline could either remain cognitively stable or could decline to a lower functioning group ov er the period of observation. Results: The annualized rates of hippocampal volume loss for each of the three initial clinical groups decreased progres sively in the following order: AD > MC > control. Within the control and MC I groups, those who declined had a significantly greater rate of volume los s than those who remained clinically stable. The mean annualized rates of h ippocampal atrophy by follow-up clinical group were: control-stable 1.73%, control-decliner 2.81%, MCI-stable 2.55%, MCI-decliner 3.69%, AD 3.5%. Conc lusion: Rates of hippocampal atrophy match both baseline cognitive status a nd the change in cognitive status over time in elderly persons who lie alon g the cognitive continuum from normal to MCI to AD.