Can Alzheimer’s disease spread from human to human?

As per a study published in the Nature journal, rare medical accidents can lead to the transmission of Alzheimer's from one human to another. The study means that in people who received human growth hormone from the pituitary glands of deceased donors the risk of developing Alzheimer's is likely because the hormones were contaminated. “We’re not suggesting for a moment you can catch Alzheimer’s disease. This is not transmissible in the sense of a viral or bacterial infection. It’s only when people have been accidentally inoculated, essentially, with human tissue or extracts of human tissue containing these seeds, which is thankfully a very rare and unusual circumstance," Prof John Collinge, co-author of the study and director of the MRC Prion Unit told the Guardian.

The study highlights that between 1959 and 1985 several patients in the UK had received human growth hormone extracted from the pituitary glands of cadavers. However, in 1985 this practice was banned after some patients subsequently died of Creutzfeldt-Jakob disease (CJD). Some of the patients were found to have amyloid-beta in their brains, a characteristic of Alzheimer's disease. "We previously reported human transmission of amyloid beta pathology and cerebral amyloid angiopathy in relatively young adults who had died of iatrogenic Creutzfeldt–Jakob disease (iCJD) after childhood treatment with cadaver-derived pituitary growth hormone (c-hGH) contaminated with both CJD prions and amyloid beta seeds. This raised the possibility that c-hGH recipients who did not die from iCJD may eventually develop Alzheimer's," the researchers have said.

Alzheimer's disease is a progressive neurodegenerative disorder that primarily affects memory and cognitive function. It is the most common cause of dementia, characterized by the accumulation of abnormal protein deposits in the brain, leading to the formation of plaques and tangles. As the disease advances, individuals experience memory loss, impaired reasoning, and difficulties with daily tasks. Alzheimer's gradually interferes with the ability to perform routine activities, impacting independence and quality of life. While the exact cause is unknown, genetic and environmental factors contribute to its development. Currently, there is no cure for Alzheimer's disease.

Early signs of Alzheimer's include memory loss affecting daily life, challenges in planning or problem-solving, difficulty completing familiar tasks, confusion with time or place, trouble understanding visual images, and new problems with words in speaking or writing. Personality and mood changes, withdrawal from social activities, and poor judgment are also indicators. While these symptoms may vary, persistent and worsening cognitive decline should prompt medical evaluation for early diagnosis and intervention. Early detection allows for better management of symptoms and planning for the future.

Risk factors for Alzheimer's include age, with increased likelihood after 65; family history and genetics; presence of the APOE-e4 gene variant; history of head injuries; cardiovascular factors like high blood pressure, diabetes, and high cholesterol; and lifestyle factors, such as lack of physical activity, poor diet, and smoking. Women and those with Down syndrome are also at higher risk. While some risk factors are beyond control, adopting a healthy lifestyle can potentially mitigate certain risks. Regular exercise, a balanced diet, mental stimulation, and maintaining cardiovascular health contribute to overall well-being and may reduce Alzheimer's risk.

While there's no guaranteed prevention, adopting a healthy lifestyle can reduce Alzheimer's risk. Stay physically active with regular exercise, follow a balanced diet rich in fruits, vegetables, and omega-3 fatty acids, maintain cardiovascular health through blood pressure and cholesterol control, engage in mentally stimulating activities, prioritize sufficient sleep, and foster social connections. Avoid smoking and limit alcohol intake. Managing chronic conditions like diabetes is crucial. Regular mental and physical health check-ups can aid early detection and intervention. These lifestyle choices collectively promote overall well-being and contribute to a lower risk of developing Alzheimer's disease.

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