386 BIOL PSYCHIATRY 1993;34:386-391 Quantified Electroencephalographic Correlates of Depression in Alzheimer's Disease Daniel Pozzi, Angel Golimstock, Ricardo Migliorelli, Alejandra Tes6n, Horacio Garcia, and Sergio Starkstein While depression is one of the mostfrequent psychiatric problems among patients with probable AIzheimer' s disease (AD), its mechanism is not well known. We performed quantified EEGs in a consecutive series of seven patients with mild dementia and depression, six patients with mild dementia and no depresswn, eight patients with moderate dementia and depression, and eight patients with moderate dementia and no depression. Regardless of the severity of dementia, depressed patients had a significantly higher percent theta in posterior brain areas. Moreover, depressed patients with mild AD showed a similar thetafrequency as non-depressed patients with moderate AD. These findings suggest that the presence of depression may contribute to the qEEG changes of AD. Key Words: Aizheimer's disease, depression, quantified electroencephalography Introduction Several studies have demonstrated significant differences in quantitative electroencephalographic (qEEG) activity between patients with Alzheimer's disease (AD) and nor. mal elderly controls (Gordon et al 1968; Gerson et al 1976; Canter et al 1982; Coben et al 1983; Duffy et al 1984a; Penttila et al 1985; Visser et al 1985). In mild dementia, theta activity is increased and beta activity is decreased (Cohen et al 1983 and 1985), while in more severe de- mentia alpha also decreases and delta activity increases (Stigsby et al 1981; Coben et al 1985; Penttila et al 1985). From the Departments of Ikhaviotal Neurology (DP, AG, RM, AT, SS) and Neumphysiology (DP, HG, SS), Rail Canea Institute of Neurological Re- search. Buenos Aires, Argentina. Address reprint requests to Dr. Sergio Starkstein. Instituto de lnve~igaciones Neu- ml6gica~ Rail Canea, Ayacucho 2166, Buenos Aires, Argentina. Received December 4. 1992; revised April 28, 1993. Primary depression (i.e., depression in the absence of known brain lesions) is also related to significant qEEG changes. Decreases in delta and increases in alpha I power are observed when depressed elderly subjects are com- pared to non-depressed age-matched controls (Brenner et al 1986). However, other authors could not find differences between elderly depressed and non-depressed subjects (Visser et al 1985). Depression is a common finding in AD, and about 50% of cross-sectional samples were reported to have (major or minor) depression (Loreck and Folstein 1993). While recent studies suggested the presence of biogenic aminc changes among patients with AD and depression (Wolfe et al 1990), the mechanism of depression in AD is still unknown. The main aim of the present study was to determine whether there are specific qEEG changes in depressed and non-depressed AD patients. We used a 2 × 2 design, with mood state (depressed or non-depressed) and severity of dementia (mild or moderate) as main factors. © 1993 $ergio Starkstein 0006-3223/93/$06.00