Early intermodality dysfunction predicts schizophrenia risk

By Lucy Piper, Senior medwireNews Reporter

Researchers have found abnormalities in the way infants of parents with schizophrenia perceive the way they move and how this relates to vision, touch, hearing, and orientation.

This ability is termed early intermodal integration (EII) and it forms the basis of “self” and complex mental and motor abilities later in life, some of which are typically disturbed in patients with schizophrenia, notes the team, led by Franziska Gamma (Center for Psychiatry and Psychotherapy, Les Toises, Lausanne, Switzerland).

It is therefore possible that “failure to develop normal EII persists as a trait in the developmental trajectory preceding schizophrenia and may be manifest in the earliest developmental phases of life well before self-disorders are observed in psychosis,” they comment in Schizophrenia Bulletin.

Indeed, the researchers found that early EII abnormalities in relation to self and objects indicated vulnerability to schizophrenia specifically, whereas EII abnormalities in relation to social interactions were risk factors for psychoses in general.

They used data from the New England Family Study high-risk sample on 58 8-month-old infants born to parents with schizophrenia, 128 born to parents with affective psychoses, and 174 born to mentally healthy parents.

The parents’ diagnoses were determined 30 years later without prior knowledge of the infants’ data.

EII abnormalities, assessed using items from the Bayley scales of mental and motor development, were studied in three domains: one’s own body (eg, inspecting own hands, responding playfully to reflection), objects (eg, sustaining interest in a ring, watching a ball being thrown), and social interactions (eg, social smiles and visual recognition of mum).

Infants born to parents with schizophrenia had EII scores in relation to objects that were a significant 36% higher than those born to mentally healthy parents. These infants were also three times more likely than control infants to fail at least one item measuring body-related EII.

Social interaction was the only domain in which infants born to both parents with schizophrenia and affective psychoses were significantly impaired compared with control infants. Average EII scores were 27% and 21% higher, respectively, compared with controls.

“[T]he results suggest a continuum of impairments in infants with [high risk] for schizophrenia on the more severe end compared with those at risk for other nonaffective psychoses and for affective psychoses,” say Gamma et al.

They conclude: “[I]f EII abnormalities reflect the premorbid state of schizophrenia, they may be part of noninvasive prevention efforts that treat developmental dysfunctions and improve the functioning of these youngsters.”

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