There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
Organic or secondary psychosis can be seen in diverse conditions such as toxic/metabolic
disorders, neurodegenerative disease, and stroke. Poststroke psychosis is a rare phenomenon,
but its study has significantly contributed to the understanding of delusion formation.
The evidence from case studies of patients with focal strokes shows that delusions
develop following unilateral damage of the right hemisphere. The majority of patients
with right hemisphere stroke do not develop delusions however, and advanced neuroimaging
analysis has elucidated why this symptom develops in only a small proportion. Lesions
of the right lateral prefrontal cortex or lesions with connectivity to this area correlate
with delusional beliefs in this subgroup. Studies of patients with primary psychosis,
for example schizophrenia, or under the influence of the psychotogenic drug ketamine,
also show abnormal function of this area in relation to the severity of their abnormal
beliefs. The conclusion of these studies is that the right lateral prefrontal cortex
is 1 hub in a neural network which includes the basal ganglia and limbic system and
receives inputs from midbrain dopamine neurones. In patients with schizophrenia, or
at risk of psychosis, dopamine is dysregulated and evidence suggests that faulty dopamine
signaling is the precursor of delusion formation. It is therefore likely that the
mechanism of delusion formation is the same in both primary and secondary psychosis.
This is consistent with the mainstay of treatment of both conditions being antipsychotic
medication. However, antipsychotic medication in people with cerebrovascular disease
should be avoided if at all possible. This is because epidemiological studies have
found that antipsychotic use is associated with an increased risk of stroke and will
thus compound the possibility of a further cerebrovascular accident.