A group of drugs that are used to treat depression, ADHD, and high blood pressure, are also effective in reducing apathy in Alzheimer’s patients.
The drugs target a neurotransmitter released in the brain called noradrenaline, which is involved in the cognitive processes of learning, concentration and emotional regulation.
In the early stages of Alzheimer’s disease, there is often damage to the area of the brain that controls the release of noradrenaline, affecting what's called the noradrenergic system. Cell loss in this area has been linked to common symptoms of dementia, including apathy – a lack of excitement or motivation.
Apathy affects somewhere between 50-70 per cent of dementia patients. More than just feeling a little low, apathy in Alzheimer’s can make it difficult to do everyday tasks, like having a shower and making food, which can lead to health problems. A person with apathy might withdraw from activities they once enjoyed, and put extra strain on the people around them.
To see whether apathy and other symptoms of dementia could be treated with drugs that target noradrenaline, scientists from the University of Cambridge, Imperial College London and University College London reviewed 19 existing studies, involving 1,811 patients.
The results showed that the drugs had positive effects on the neuropsychiatric symptoms of apathy and agitation, and also on overall cognition in patients.
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While there is still much to learn about the relationship between Alzheimer's and noradrenaline, if already existing drugs that target the neurotransmitter could be repurposed, it could offer an effective Alzheimer’s treatment in a relatively short time.
"Apathy is one of the most common symptoms in Alzheimer's, and it is not fully understood," said Dr Michael David, a dementia researcher at Imperial College London and one of the study's authors.
"There is a dynamic, likely two-way, relationship between apathy and cognitive impairment, where dysfunction in the noradrenergic system could prevent patients from recognising things that require them to act – in essence creating an apathetic state."
However, further clinical trials would be needed, especially to answer questions about the dosage and the drug’s interactions with other medications given for dementia, say researchers.
"At present there is no approved, specific medication for apathy in Alzheimer’s disease. The data for methylphenidate, a drug included in the current meta-analysis, are promising, but there is no approved drug for this very common and disabling symptom," said Dr Paresh Malhotra, a neurologist at Imperial College London, who worked on the new study.
The group are now looking to run further clinical trials. One trial, ofa noradrenergic medication called guanfacine that is used in ADHD, is being run at Imperial by Malhortra.
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