DISCRIMINANT-ANALYSIS OF MRI MEASURES AS A METHOD TO DETERMINE THE PRESENCE OF DEMENTIA OF THE ALZHEIMER-TYPE

Multivariate discriminant analysis of brain volumes obtained from semi automated magnetic resonance image (MRI) quantification was used in an attempt to identify demented patients very early in the course of the disease. Temporal and posterior frontal brain volumes were quantified from MRIs in a cross-sectional study of 31 male and female patients w ith dementia of the Alzheimer type (DAT) and 29 age- and sex-matched h ealthy comparison subjects. Mean scores on the Folstein Mini-Mental St ate Examination (MMS) were in the mild range for the DAT group (20 +/- 6.6), but patients with moderate and severe dementia were also includ ed (MMS range of entire DAT group = 4-28). Significant mean difference s in frontal and temporal lobe brain volumes were found between the DA T group and the age-and sex-matched healthy comparison group, but the sensitivity of any single measure was limited to 87% with a specificit y of 83%, Initial multivariate discriminant analysis revealed signific ant gender differences among the healthy subjects, but not the DAT pat ients, The large group size allowed for subsequent discriminant analys es to be performed by gender, All healthy subjects and DAT patients we re correctly classified by gender-specific discriminant functions. The male discriminant function variables included brain volume, age, and temporal lobe measures. Inclusion of age in the male discriminant func tion accounted for age-related brain atrophy, a finding that may have emerged as a consequence of the broad age range of the male DAT popula tion (50-81 years), The male discriminant function was also successful ly applied to an independent group of mildly demented subjects that in cluded patients for whom the diagnosis of dementia was uncertain but v erified by follow-up clinical evaluations. Measures of temporal lobe b rain matter and temporal lobe cerebrospinal fluid volumes were the sig nificant discriminator variables for the women. Quantitative MRI and m ultivariate discriminant analysis showed promise in distinguishing the dementing process from healthy aging in a group of 60 subjects, Moreo ver, while not diagnostic of DAT, the approach appeared to offer addit ional information about the probability of a diagnosis being later con firmed in patients with very mild dementia for whom the clinical ident ification of DAT is uncertain.