The concept of target features in schizophrenia research

Abstract

Target features are clinical or neurobiological characteristics that are expressions of the underlying predisposition to an illness. They comprise a wide range of phenomena, from the classic signs and symptoms of psychopathology to sophisticated measures of brain structure and function. For schizophrenia, many target features have been identified. These include eye tracking dysfunction, attentional impairment, allusive thinking, neurological signs, thought disorder, characteristic auditory evoked potentials, neuropsychological impairment, structural brain abnormalities and functional brain abnormalities. In their most pathological forms, thcse features are present among many schizophrenic patients, yet it is their presence among their non‐psychotic relatives that shows them to be target features. We discuss the theoretical background for target features, present examples and describe how the discovery of target features has implications for schizophrenia research.

Neurological soft signs as candidate endophenotypes for schizophrenia: A shooting star or a Northern star?

“…The crucial role of neurological abnormalities or signs in schizophrenia has been recognized by researchers in the past decades (e.g., Tsuang et al, 1991;Torrey et al, 1994;Tsuang and Faraone, 1999). Tsuang et al (Tsuang et al, 1991;Tsuang and Faraone, 1999) considered neurological abnormalities as the ''target features'' that encompass the idea that genetic and nongenetic processes lead to maldevelopment in neurocognitive systems.…”

“…Tsuang et al (Tsuang et al, 1991;Tsuang and Faraone, 1999) considered neurological abnormalities as the ''target features'' that encompass the idea that genetic and nongenetic processes lead to maldevelopment in neurocognitive systems. Target features are defined as ''clinical or neurobiological characteristics that are expressions of the underlying predisposition to the illness (schizophrenia)'' .…”

“…The model considers illness as resulting from multiple genetic and environmental variables that may be additive or interactive. According to Tsuang and Faraone (1999), these variables act upon three stages of the illness, namely neurodevelopment, later adolescence (around onset), and after the onset of psychosis. This model further accommodates etiological heterogeneity by postulating that if a smaller proportion of variables out of a large pool are sufficient for expression of the illness, then a wider range of different permutations of underlying variables could be associated with illness manifestations.…”

Neurological soft signs in schizophrenia - The past, the present and the future

“…Target features are defined as “clinical or neurobiological characteristics that are expressions of the underlying predisposition to the illness”. [13] Neurological abnormalities have been considered as the “target features” that encompass the idea that genetic and non-genetic processes lead to maldevelopment in neurocognitive systems. Neural system abnormalities give rise to both soft signs and cognitive impairments.…”

Obstetric complications and neurological soft signs in male patients with schizophrenia

“…NSS involve observable defects in sensorial integration, motor coordination and inhibition. The role of NSS in schizophrenia is still unclear: Tsuang et al (10,11) have argued that these defects reflect genetic and non-genetic processes underpinning the predisposition to psychotic illness. NSS have also been described in children at risk of schizophrenia (7), in drug-naïve patients at first psychotic episode (8) and appear to be related to cognitive impairment (9).…”