Schizophrenia is more than simply positive symptoms; the syndrome includes cognitive and negative symptoms as well.[Owen et al., 2016; Stahl, 2013] The negative symptoms of schizophrenia include dysfunction of:[Stahl, 2013]
- communication (alogia)
- affect (affective blunting)
- socialisation (asociality) c
- apacity for pleasure (anhedonia)
- motivation (avolition).
It is hypothesised that the cognitive, and some of the negative, symptoms of schizophrenia arise due to a deficit of dopamine activity in mesocortical projections to areas of the dorsolateral prefrontal cortex, whereas affective and other negative symptoms of schizophrenia may be due to a deficit in projections to areas of the ventromedial prefrontal cortex.[Stahl, 2013] One of the conundrums of treating patients with schizophrenia, therefore, has been that to treat both positive and negative symptoms, dopamine levels need to be simultaneously decreased (in the mesolimbic pathway) and increased (in the mesocortical pathway).[Stahl, 2013] Additionally, it is becoming increasingly clear that the symptoms of schizophrenia stem from disruptions in multiple neurotransmitter systems, rather than simply involving dopaminergic signalling.[Aleman et al., 2017; Tripathi et al., 2018]
References:
Aleman A, Lincoln TM, Bruggeman R, et al. Treatment of negative symptoms: where do we stand, and where do we go? Schizophr Res 2017; 186: 55–62.
Owen MJ, Sawa A, Mortensen PB. Schizophrenia. Lancet 2016; 388 (10039): 86–97.
Stahl SM. Stahl’s Essential Psychopharmacology. Neuroscientific Basis and Practical Applications. Fourth Edition. © Cambridge University Press, 2013.
Tripathi A, Kar SK, Shukla R. Cognitive deficits in schizophrenia: understanding the biological correlates and remediation strategies. Clin Psychopharm Neurosci 2018; 16 (1): 7–17.