A protein found in deposits in the brains of people with Alzheimer's disease may have been passed on via injections of human growth hormone, finds a study published in this week's Nature.
The protein beta-amyloid was observed in seven of the eight cases examined, suggesting that they may have gone on to develop Alzheimer's disease had they lived longer.
Growth hormone extracted from brains of the deceased were given to 1,848 people in the UK between 1958 and 1985 but the practice was discontinued when it was found to cause the prion disease Creutzfeldt-Jakob Disease (CJD) in 3.6% of patients.
Professor Collinge and colleagues at UCL examined the brains of eight people who received human growth hormone injections and died with CJD aged between 36 to 51 years of age. The Alzheimer's protein beta-amyloid was present in seven of the eight brains, with widespread deposits observed in four cases. Although beta-amyloid deposits can occur with natural ageing, it is unusual to see them to this extent in the brains of people in this age range.
None of the brains examined had any evidence of tau neurofibrillary tangles, which is a second key hallmark of Alzheimer's disease, nor was there any evidence of Alzheimer's disease in their clinical records.
Dr Doug Brown, Director of Research at Alzheimer's Society, said:
'While these findings are interesting and warrant further investigation, there are too many unknowns in this small, observational study of eight brains to draw any conclusions about whether Alzheimer's disease can be transmitted this way.
'Notably, while seven of the eight brains studied had beta-amyloid deposits - a protein found in the brains of people with Alzheimer's disease - the presence of this alone does not mean that they would have gone on to develop the disease.
'Injections of growth hormone taken from human brains were stopped in the 1980s. There remains absolutely no evidence that Alzheimer's disease is contagious or can be transmitted from person to person via any current medical or dental procedures.'