The Schizophrenia Proneness Instrument, Child and Youth version (SPI-CY) has its origin in the basic symptom concept first described by Gerd Huber.
Basic symptoms are subtle, subclinical, self-experienced disturbances in drive, stress tolerance, affect, thinking, speech, perception and motor action, which are phenomenologically distinct from frank or attenuated psychotic symptoms. Basic symptoms can be present before, during and after psychotic episodes. The term “basic” reflects the belief that they are the first specific psychological manifestation of the neurobiological disturbance underlying the development of psychosis.
Basic symptoms are phenomenologically different from normal, non-pathological, fluctuations in mental state. In other words they are different from what a young person considers his or her normal self, and in this way may be distinguished from those subtle disturbances that occur as long-standing traits in children at genetic high-risk.
Generally speaking, the SPI-CY can be used to assess young people of 8 years and above, with the caveat that some basic symptoms require a higher cognitive-developmental state and should not be assessed before the age of 13. Whilst, as for adults, the elicitation of subjective experience remains critical to identifying basic symptoms, the SPI-CY may also utilize information from parents and other carers. However, such third-party information may only be used to help explore what the young person is experiencing, and cannot act as a substitute for directly elicited information.