Focusing on schizotypy may allow for some of the
mechanisms to be disentangled through more detailed investigation
without clinical complications such as medications and contact time in
the clinic.
Other treatments, including noninvasive stimulation approaches (e.g.,
transcranial direct current stimulation: tDCS; transcranial magnetic
stimulation: TMS), report improvements in sensory and cognitive markers,
and reduce symptoms (reviewed in (Berryhill & Martin, 2018). For
example, anodal tDCS improved pitch MMN amplitude and 2-back WM
performance in people with schizophrenia (Impey et al., 2017). A
separate study reported improved auditory P50 ERP response and reduced
auditory hallucinations after anodal tDCS (Kim et al., 2018). In
treatment resistant individuals with schizophrenia, a TMS protocol
(intermittent theta burst stimulation) targeting left PFC improved
visual WM ability and reduced symptoms (Wang et al., 2022). However, a
recent meta-analysis evaluating findings from TMS and tDCS approaches
reports no collective benefit across 22 studies (Sloan et al., 2021).
Early-stage neurostimulation findings show promise, in terms of behavior
and normalized biomarkers. However, small sample sizes, brief protocols,
and a variable clinical population contribute to heterogeneous outcomes
and a need for optimization. It is also unclear how
stimulation methods would impact a less symptomatic population,
particularly if the biomarkers in schizotypy are less pronounced than
they are in diagnosed individuals.
Can Biomarkers be Used to Predict Schizophrenia
Onset?
When assessing biomarkers of symptom severity, there is a burgeoning
question as to whether some of the biomarkers already
discussed here can be used to predict the onset of schizophrenia.