Background and objectives: One of the pathogenetic hypotheses of delirium is the "neuroinflammatory theory" with consequent neurotoxicity of brain connectivity networks. Micronutrients may play a significant role in the prevention of neuroinflammation. This systematic review addresses the role of micronutrients in the development of delirium in older populations.

Methods: The EBSCO, Cochrane, PubMed, and Web of Science databases were searched for articles on delirium and micronutrients. The methodological quality of the studies included in the review was evaluated with the Newcastle-Ottawa Scales for observational studies and for case-control studies.

Results: 1326 papers were identified from the searches, 7 of which met the inclusion criteria (see section 2.3). All the papers included were written in English. Delirium was predominantly secondary to post-operative dysfunction or acute medical conditions. By altering the production of neurotransmitters resulting in an imbalance, and by reducing their immunomodulatory role with a consequent increase in inflammatory oxidative stress, micronutrient deficiency seems to be associated with an increased incidence of delirium.

Conclusions: This review supports the existence of an association between micronutrient deficiency (i.e. cobalamin, thiamine, and vitamin D) and an increased incidence of delirium, with a greater prevalence in hospitalized patients.