title: Reduced ERPs and theta oscillations underlie working memory deficits in Toxoplasma gondii infected seniors.
abstract: Toxoplasma gondii is one of the most widespread infections in humans. Recent studies give evidence for memory deficits in infected older adults. To investigate working memory dysfunction in infected elderly, a double-blinded electrophysiological study was conducted. 84 persons derived from a sample of 131 healthy participants with the mean age of 70 years were assigned to two groups of 42 non-infected and 42 infected individuals. The outcome measures were behavioral performance, target and response-related ERPs, and time-frequency wavelets during performance in a n-back working-memory task. The infected individuals showed a reduced rate of detected targets and diminished P3b amplitude both in target-locked as well as response-locked data compared to the non-infected group. Time-frequency decomposition of the EEG-signals revealed lower evoked power in the theta frequency range in the target-locked as well as in the response-locked data in infected individuals. The reported effects were comparable with differences between healthy young and old adults described previously. Taking together, the reduced working-memory performance accompanied by an attenuated P3b and frontal theta activity may suggest neurotransmitter imbalance like dopamine and norepinephrine in T. gondii infected individuals. In face of a high prevalence of T. gondii infection and the increasing ratio of older population their accelerated memory decline may have substantial socioeconomic consequences.
authors: Leibniz Research Centre for Working Environment and Human Factors at TU Dortmund (IfADo), Dortmund, Germany. Electronic address: gajewski@ifado.de.
authors: Patrick D
authors: PD
authors: Gajewski
authors: Leibniz Research Centre for Working Environment and Human Factors at TU Dortmund (IfADo), Dortmund, Germany.
authors: Michael
authors: M
authors: Falkenstein
authors: Leibniz Research Centre for Working Environment and Human Factors at TU Dortmund (IfADo), Dortmund, Germany.
authors: Jan G
authors: JG
authors: Hengstler
authors: Leibniz Research Centre for Working Environment and Human Factors at TU Dortmund (IfADo), Dortmund, Germany.
authors: Klaus
authors: K
authors: Golka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004311:Double-Blind Method; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000469:parasitology* / Q000503:physiopathology; D008570:Memory, Short-Term / Q000502:physiology*; D013826:Theta Rhythm / Q000502:physiology*; D014123:Toxoplasmosis / Q000503:physiopathology / Q000523:psychology*
keywords: Aging; Dopamine; Event-related potentials (ERPs); Norepinephrine; Response-locked ERPs; Stimulus-locked ERPs; Theta; Toxoplasma gondii; Working memory