A rodent study found repetitive anaesthesia with isoflurane (one of the most common anaesthetics by inhalation) increases the risk of developing Alzheimer's disease (AD) like symptoms in patients with genetic risk factors for the disease.
Spanish researchers coordinated by Doctors Maria Angeles Mena and Justo Garcia de Yebenes, from CIBERNED (Centro de Investigacion Biomedica en Red de Enfermedades Neurodegenerativas), found that anaesthesia is safe for normal mice but potentially harmful for mice with mutations of the amyloid precursor protein (APP).
The findings suggest a possible mechanism of developing Alzheimer.
Some epidemiological studies have shown an increased prevalence of AD in patients undergoing anaesthesia and surgery.
"Before surgery requiring anesthesia, it may be ideal to know the genetic background of the patients so that the drugs used and the pattern of anaesthesia may be personalized accordingly,' said de Yebenes.
The linkage between the repetitive use of isoflurane anaesthesia and the development of AD changes in mice with mutations indicates the advisability of testing for genetic risk factors for AD in patients prior to surgery.
The researchers concluded that anaesthesia is safe for normal mice but risky for asymptomatic carriers of mutations, which produce AD.
The research has been based on the application of anaesthesia twice a week during three months in normal mice and in mice with mutations (7-10 months old) that produce AD (known as APPswe).
The results show alterations produced in the brain of mice with mutations very similar to those observed in patients that have already developed Alzheimer's disease.
It was found that application of repetitive anaesthesia in genetically altered mice increased their death rate.
Mutant mice showed less reactivity after anaesthesia was over. Their time for recovery after anaesthesia was also increased.
Repetitive anaesthesia produced persistent disorders affecting behavior of mutant mice.
Neuronal death increased in brain areas critical for cognition.
There was an increase in inflammatory response and deposition of beta-amyloid peptides.
Isoflurane anaesthesia of mutant mice altered the levels of chaperones (proteins which regulate the processing of abnormal proteins)
The work has been published in the Journal of Alzheimer's Disease.