Stem cell therapies and Alzheimer’s disease
The last of these drugs is Memantine and works differently to the other three. It blocks the effects of a chemical in the brain called glutamate. Like acetylcholine, glutamate is another chemical that helps to send messages between nerve cells in the brain. 27 It binds to NMDA receptors found on the nerve cells. Levels of these neurotransmitters need to be balanced. However, when nerve cells are damaged during the disease, too much glutamate is produced which can damage the nerve cells by excessively stimulating the NMDA receptors. Memantine protects nerve cells by blocking the effects of too much glutamate. It does this by blocking the NMDA receptors in the brain. 28 Memantine and cholinesterase inhibitors can be prescribed together. On the other hand, Memantine can act as an alternative to the other three, due to the side effects which may present in a patient. Common side effects of AChEs include loss of appetite, nausea, vomiting, and diarrhoea. With Memantine, the side effects are less common and less severe. Furthermore, in the later stages of Alzheimer’s disease, many people develop behavioural and psychological symptoms (BPSD). These include delusions, hallucinations, agitation, and aggressive behaviours. There are non-drug approaches that can help relieve these symptoms within a couple of weeks and are effective. However, other medications can be given if the non-drug approaches have been exhausted and improvement has not been noticed. These are only prescribed if the patient is within the moderate and severe Alzheimer’s disease stages, or if the symptoms put the person at risk of harm to themselves or others. For example, the use of antidepressants such as selective serotonin reuptake inhibitors (SSRIs) can be prescribed to reduce agitation symptoms in patients, or antipsychotics such as Risperidone. It is vital that other treatment methods are exhausted for these drugs to be used. This is due to the serious side effects such as increased risk of blood clots, ankle swelling and stroke. In the long term, any benefits from reducing BPSD may be at the expense of quality of life, so may infringe on the patient’s successful treatment. These drugs are used to delay progression of cognitive decline and prevent worsening cognitive function. The National institute for Health and Care Excellence (NICE) recommends that the acetylcholinesterase inhibitors should be offered during the earlier stages of the disease. 40-70% of the people with Alzheimer’s disease finds that taking these drugs improve symptoms. An analysis reported that use of memantine to treat BPSD led to modest decreases in scores on the Neuropsychiatric Inventory Questionnaire and improvement of symptoms, with sedation as a major side effect. Doctors notice that the symptoms improve temporarily for around 6-12 months, before the effect wears off and symptoms worsen gradually. These pharmacological methods can have a benefit in the short term, but they do not halt AD progression, and drug success must be monitored very frequently so that the risks to the patient’s health can be seen in advance before it occurs. 29
27 Memantine 2015. 28 Ibid. 29 For information in this paragraph, see The effect of Alzheimer’s Di sease drugs n.d.
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