Alteration of frontal EEG asymmetry during tryptophan depletion predicts future depression

Tryptophan depletion (TD) reduces brain serotonin and may induce acute depressive symptomatology, especially among those with a history of Major Depression. Depressive response to TD among euthymic patients with a history of depression also predicts future depression. Better prediction might result by assessing a putative endophenotype for depressive risk, frontal electroencephalographic (EEG) asymmetry, in the context of TD.

Nine euthymic history-positive participants and nine controls were administered TD. Symptomatic and EEG frontal asymmetry data were collected for 6 h following TD, and clinical status was followed for the next 12 months.

The magnitude of TD-induced change in frontal EEG asymmetry significantly predicted the development of depression during the ensuing six to twelve months, and with greater sensitivity than symptomatic response.

The results are tempered by the small sample size.

Despite the limited sample size, these preliminary results suggest that TD-induced changes in frontal EEG asymmetry may provide a more sensitive indicator of risk for imminent depression than symptomatic response to TD.