EEG and the Test for the Early Detection of Dementia with Discrimination from Depression (TE4D): a validation study

The Test for the Early Detection of Dementia with Discrimination from Depression (TE4D) was developed as a screening instrument for mild dementia. We investigated the convergent validity of the TE4D to EEG and other psychometric tests in patients suffering from dementia and depression.

In 47 patients suffering from Alzheimer's disease (ICD-10 F.00) and 16 patients with affective disorders (F30-F39) the tests TE4D, ADAS-cog, SKT, BCRS, MMSE were performed and an EEG recorded. Group differences were compared by t-tests and a regression analysis was calculated.

The inter-test-correlations varied between rs = 0.77 and rs = 0.91. Significant differences between the diagnostic groups were found for all tests as well as for the frequency bands alpha and beta. For the qEEG, significant positive correlations were found between TE4D (Dementia subscore) and the mean frequency (r = 0.47), the peak frequency (r = 0.42), the frequency bands alpha (r = 0.59) and beta (r = 0.56) as well as negative correlations in the frequency bands delta (r = -0.23) and theta (r = -0.42). The mean frequency and the activity in the frequency bands alpha, beta2, delta and theta contributed to the regression equation. The correlation between regression equation and the TE4D was rs = 0.87. The other tests also correlated with the TE4D: ADAS rs = -0.75, MMST rs = 0.82, SKT rs = -0.74, BCRS rs = -0.83.

The TE4D showed convergent validity with the EEG parameters. Both the TE4D-score and the EEG-alterations correlated significantly with the degree of severity of Alzheimer's disease. This result underlines the assumption that the TE4D will be a useful instrument for the diagnostic process in dementia.