ABSTRACT
Th e division of symptoms associated with schizophrenia into positive and negative does appear to have merit. Positive symptoms involve distortions and typically added mental activity beyond what is normal, whereas negative symptoms entail something removed from what is normal, and usually reduced mental activity (Arango et al, 2004; Bowins, 2011; Langdon et al, 2014). In addition, diff erences in course of illness, symptoms, response to treatment, neurochemistry relevant to pharmacological intervention, neurobiology, neuropsychological functioning, family history, premorbid adjustment, and risk factors support such a distinction (Arango et al, 2004; Carpenter et al, 1999; Fanous et al, 2001; Fenton & McGlashan, 1994; Horan & Blanchard, 2003; Kirkpatrick et al, 2000; Kirkpatrick et al, 2001; Klemm et al, 2006; Lahti et al, 2001; Malaspina & Coleman, 2003; Pogue-Geile & Harrow, 1984; Vaiva et al, 2002). Psychosis (positive symptoms) tends to be episodic and responds very well to antipsychotic medications that work by blocking dopamine, while negative symptoms develop gradually in a long prodromal phase and are quite resilient to treatment, with extensive eff orts such as cognitive remediation oft en producing limited gains that frequently do not generalize beyond the task (Addington & Addington, 2009; Amador et al, 1999; Arango et al, 2004; Buchanan et al, 1990; Dickinson et al, 2010; Galletly, 2009; McCullumsmith et al, 2004). Negative symptoms do not respond at all well to dopamine blockage, and if anything seem to involve alternative neurochemical receptors and transmitters, such as serotonin receptors (including 5HT-1A and 5HT-2A), glycine, and glutamate (NMDA receptor subtype) (Galletly, 2009; Goff & Coyle, 2001; Gupta & Kulhara, 2010; Heresco-Levy, 1999; Javitt, 2008; Lane et al, 2005; Uchida et al, 2011). Also of fundamental importance, cognitive impairments are much more strongly linked to negative than positive symptoms (Bilder et al, 2000; Daly et al, 2012; Helldin et al, 2006; Kimhy et al, 2005; Lucas et al, 2004; Rossi et al, 1997; Smith et al, 2009).
