Can specific deficits in executive functioning explain the negative symptoms of schizophrenia? A review.

The relationship between clinical symptoms and neurocognitive impairment has been a growing interest in the field of schizophrenia research. We review the empirical evidence for whether some schizophrenia symptoms can be viewed as expressions of disordered executive functioning. A specific focus of our review is Frith's (1992) neurocognitive theory of negative symptoms, and whether this theory is supported by studies of executive functioning in schizophrenia. The current trend towards viewing executive functioning in terms of fractionable cognitive processes is discussed. Difficulties with traditional clinical measures (e.g. the Wisconsin Card Sorting Test; WCST) in separating these processes are highlighted. Neurocognitive studies of schizophrenia are then reviewed in terms of this fractionated view of executive processes. We conclude that a more specific approach to executive functioning deficits in schizophrenia using more selective measures is needed before stronger conclusions can be drawn about their relationship to clinical symptoms.