MAJOR UNIPOLAR DEPRESSION AND MILD ALZHEIMERS-DISEASE - DIFFERENTIATION BY QUANTITATIVE TONIC REM-EEG

In a previous report, tonic REM sleep epochs from the all-night sleep EEG were processed and analyzed to produce a diagnostic that discrimin ated mild Alzheimer's disease (AD) from cognitively unimpaired control subjects. Here, we examine the specificity of this diagnostic in dist inguishing depression from AD. Twenty-four cognitively unimpaired seni ors (aged 63 +/- 1.3) with major depressive disorder (unipolar) were m onitored for all-night EEG in a manner identical to that used in our p revious report. Tonic REM EEG epochs Were preconditioned, spectrally a nalyzed and compared with known populations of control and AD EEG spec tra. Instances when a given depressed subject's spectra fell within sp ectral zones unique to control or AD populations formed a diagnostic s core (control. AD, neither of these). Diagnostic scores correctly iden tified 88% (21/24) of cognitively unimpaired seniors with major depres sive disorder (unipolar). This can be compared with 89% (31 /35) of mi ld AD subjects and 100% (43/43) of control subjects correctly identifi ed in our previous report. This diagnostic also correctly classified a s to eventual clinical AD/not AD outcome 8 subjects with both major de pressive disorder and validated memory complaints. The diagnostic disc rimination of AD is based on the fact that AD subjects have significan tly less tonic REM EEG energy in the 13-30 Hz frequency range and more in the 1-10 Hz range than control or depressed subjects, as shown in conventional spectral analysis.