For both clinical and research reasons, it is essential to identify which mild cognitive impairment (MCI) subjects subsequently progress to Alzheimer's disease (AD). The prediction may be facilitated by accelerated whole brain atrophy exhibited by AD subjects. Iterative principal component analysis (IPCA) was used to characterize whole brain atrophy rates using sequential MRI scans for 102 MCI subjects from the Kuopio University Hospital. We modelled the likelihood of progression to probable AD, and found that each additional percent of annualized whole brain atrophy rate was associated with a higher odds ratio (OR) of progression (OR=1.30, p=0.01, 95% CI=1.05-1.60). Our study demonstrates an association between whole brain atrophy rate and subsequent rate of clinical progression from MCI to AD. These findings suggest that IPCA could be an effective brain-imaging marker of progression to AD and useful tool for the evaluation of disease-modifying treatments.