A psychobiologic analysis of cognitive failures. Structure and mechanisms

Impairments in memory, learning, and related cognitive functions can vary in most psychiatric or neuropsychiatric disorders. Although many methods have been used to measure the presence and severity of cognitive symptoms, little progress has been made in defining and contrasting possible determinants of cognitive dysfunction. We propose a theoretical framework that describes impairments of higher mental functions in terms of both "extrinsic" noncognitive processes and "intrinsic" cognitive processes. The latter include effort (capacity) demanding processes; automatic processes; episodic (recent biographical) memory; and processes involved in accessing previously acquired knowledge. Noncognitive processes include sensitivity to reinforcement, activation, sensorimotor function, and mood. Each of these processes can be expressed at the time of information acquisition or retrieval from memory. Findings from clinical studies of patients suffering amnestic disorders, progressive dementias, and mood disorders illustrate the utility of such a model for understanding some of the determinants of cognitive dysfunction, for developing diagnostic tools, and for considering therapeutic strategies that may be useful in treating cognitive dysfunctions.