A drug that suppresses the immune system to prevent transplant patients' bodies from rejecting their new organs may also protect against Alzheimer's disease, a new study has found.
It is known that toxic protein aggregates called Amyloid beta oligomers selectively target and disrupt the points of communication between brain cells, impairing memory in people suffering from Alzheimer's disease.
Calcineurin is an enzyme that regulates communication between brain cells and memory formation.
Researchers have shown previously that this enzyme plays a central role in the harmful effects of the Amyloid beta oligomers and that elevated calcineurin is found in the nervous system of Alzheimer's patients.
However, the question of whether blocking calcineurin would prevent the onset and progression of Alzheimer's in people is challenging because treatment with a calcineurin-blocking agent suppresses the immune system.
In the new study, researchers from the University of Texas Medical Branch (UTMB) at Galveston analysed data from the medical records of 2,644 patients who received organ transplants and and must take calcineurin inhibitor-based medications, such as Tacrolimus or cyclosporine, for the rest of their lives to prevent rejection of the transplanted organ.
As part of the medical care for transplant recipients, any evidence of memory impairment or dementia is immediately noted and monitored, as it can limit treatment compliance among these patients.
The participants were separated into groups by age at the time of last visit or death, gender and ethnicity. Eight participants showed evidence of dementia - two were younger than 65, five were in the 65-74 years old group and one was in the 75-84 years old group.
The study data was compared with national data obtained from the 2014 Alzheimer's Association Facts and Figures dataset on age-matched patients to compare the prevalence of Alzheimer's in the US.
"These data clearly show that the prevalence of dementia and Alzheimer's in our transplant patient group is significantly lower, in fact almost absent, when compared to national data from the general population," said senior author Luca Cicalese, professor in the department of surgery.
"In patients over 65 years, 11 per cent of the general population had dementia compared with 1.02 per cent of the study subjects.
"In Americans over 75 years, 15.3 per cent of the population had dementia compared with 0.6 per cent of the study subjects. Among Americans over 85 years, 32 per cent had dementia, although we did not have any patients in this age group with dementia," Cicalese said.
The researchers are currently working on devising treatment strategies to obtain the same beneficial effects in humans with the disease using low doses of calcineurin inhibitors that result in minimal or no immunosuppression, thus limiting possible undesired side effects.
The study was published in the Journal of Alzheimer's Disease.
