Acetylcholine has been implicated in both the pathophysiology and treatment of a number of
psychiatric disorders, with most of the data related to its role and therapeutic potential focusing on
schizophrenia. However, there is little thought given to the consequences of the documented changes in the
cholinergic system and how they may affect the functioning of the brain. This review looks at the
cholinergic system and its interactions with the intrinsic
neurotransmitters glutamate and gamma-amino
butyric acid as well as those with the projection
neurotransmitters most implicated in the pathophysiologies of
psychiatric disorders;
dopamine and
serotonin. In addition, with the recent focus on the role of factors normally associated with
inflammation in the pathophysiologies of
psychiatric disorders, links between the
cholinergic system and these factors will also be examined. These interfaces are put into context, primarily for
schizophrenia, by looking at the changes in each of these systems in the disorder and exploring, theoretically, whether the changes are interconnected with those seen in the
cholinergic system. Thus, this review will provide a comprehensive overview of the connectivity between the
cholinergic system and some of the major areas of research into the pathophysiologies of
psychiatric disorders, resulting in a critical appraisal of the potential outcomes of a dysregulated central
cholinergic system.