Event related oscillations in alzheimer disease

The brain pathology in Alzheimer type of dementia (AD) is well known. This thesis has been planned to investigate the changes in brain dynamics in subjects with AD. The analysis of brain dynamic responses have been realized by means of event related oscillations (ERO). The classical visual P300 oddball paradigm has been given to the twenty healthy elderly control subjects and twenty-two AD subjects. AD group has been divided into two groups: those treated by cholinesterase inhibitors and de novo. Two AD groups have been matched by disease duration, gender, education and age. Both patient groups consisted of eleven subjects. EEG was recorded from 13 scalp electrodes (F3, F4, Cz, C3, C4, T3, T4, T5, T6, P3, P4, O1, O2). The mean peak amplitudes at the frequency ranges of 0.5-3.5 Hz (delta), 5-8.5 Hz (theta), 9-13 Hz (alpha), 15-24 Hz (beta) were digitally filtered and analysed. In addition, theta phase locking which is considered as closely related to memory was also investigated.Significant differences in peak amplitudes of delta frequency range were seen between the groups at mid- and left central regions, (Cz, C3) being higher in healthy controls than either patient group (F (9.120)=2.228; p=0.022). The phase locking of theta oscillations at F3 location was significantly higher in treated AD group than either healthy controls (p= 0.044) or de novo AD (p= 0.026) groups.In clinical practice, ERO in delta frequency ranges may be adjuctive for diagnostic purposes, whereas theta responses may help monitoring the treatment responses. This study once more supports the importance of oscillatory event related potentials for investigating AD brain dynamics.Keywords: Alzheimer, dementia, oscillations, delta, theta, visual, P300, EEG, event related potentials, ERP