Adapted from BMJ 2-9 May 2026
Unfortunately a Cochrane study has revealed that new drugs for dementia that target amyloid protein in the brain, just don’t make a clinical difference to the patient.
Although amyloid beta protein accumulates in the brain in Alzheimer’s dementia, and the drugs do help to clear this up, there is no significant difference to the mental functioning of the patients. In addition the drugs increase the risk of swelling and bleeding in the brain. The findings were reported by Francesco Nonino the lead author, who is a lead author, neurologist and epidemiologist.
The review examined 17 randomised controlled trials, involving 20,342 participants aged 70-74 with mild cognitive impairment or mild dementia from Alzheimer’s disease. Seven different monoclonal antibody drugs were tested and the outcomes assessed against placebo. The drugs all have different mechanisms of action. The studies lasted 18-24+ months. Two of the drugs, donanemab and lecanemab are licenced in the UK.
Disappointingly, there was no difference in cognitive function between the groups. There were small increases in brain swelling and bleeding, but no other side effects.
As as result there could be changes in the prescription guidance of these drugs, particularly as they are very expensive. They can cost up to £32,600 for each patient in the USA per year.
The authors recommend that other pathways be looked at for the development of new drugs and that the amyloid hypothesis be put to rest.
My comment: These drugs, particularly Donezepil, have been prescribed for quite a few years. I did see one man who had a great response to the drug. He was being cared for by his wife. He would hide under the bed thinking that he was back in the war and under attack. He got the drug and his response was fantastic. He was so good that he became her carer when she got dementia. Unfortunately he was the only patient from whom there was any noticeable change when I was a GP. In the UK the drug is only £18-30 per patient per year. I would imagine that a three month trial of the drug may be reasonable and if there is no clinical response it could be stopped. Money would be better spent on social and nursing care. No doubt clinical guidelines will be changed after this important study. Already there are calls to delay the onset of Alzheimer’s and other dementias by recommending population approaches such as measures to prevent obesity, increase exercise, decrease smoking, improve sight and hearing, and encourage social meetings and lifelong learning. If you have diabetes, good control will also reduce your risk.
