We appreciate the important comments of Frisoni and colleagues. We also read their original article.1 The stable mild cognitive impairment (MCI) group was characterized by essentially no progression of cognitive function during observation period and no elevation of cerebrospinal fluid-tau values. Our authors have emphasized and shed light on the presence of “MCI with non-Alzheimer type” as a common subtype of MCI in a clinical setting.2,3 However, this type of MCI has often escaped attention and may have been underestimated. Since a large proportion of the stable MCI group had moderate to severe periventricular white matter lesions and related vascular risk factors, it should be recommended to reduce modifiable risk factors and to maintain healthy lifestyles to prevent not only symptomatic but also silent stroke. We assume that stable MCI may include a broad spectrum of cognitive change. An example would be Parkinson disease or chronic alcoholism rather than “MCI of the vascular type (MCI-V)” alone. Therefore, stable MCI might be etiologically heterogeneous.4 Neuropsychological profiles of the stable MCI will be addressed in a different study. As we mentioned in our article, we studied consecutive and unselected individuals who came to our memory clinic. Comorbid diseases were treated adequately. A dramatic difference between patients with stable MCI and patients with MCI-V1 was noted in prognosis and adverse outcomes despite a comparable profile of vascular risk factors. Indeed, during a follow-up of 32 ± 8 months, about 30% of the MCI-V patients died, whereas none of our stable MCI patients died or were placed in nursing homes over an observation period for 2 years. We are afraid that the MCI-V group may be more frail with poorer health profiles compared with the stable MCI group.
Arai H, Maruyama M. The Heterogeneity and Natural History of Mild Cognitive Impairment—Reply. Arch Neurol. 2005;62(1):163-164. doi:10.1001/archneur.62.1.163-b