Alzheimer’s disease stands as a progressive neuro-degenerative disorder making a high social impact. The number of cases of dementia globally is on the incline and by 2050 it is expected to double or treble with the majority of dementia cases being due to Alzheimer’s disease. Treatment of Alzheimer’s disease has been challenging due to many reasons such as poor early detection, invasive diagnostic and treatment methods, lack of investment to train health professionals to conduct testing, and stigma associated with the disease condition which prevents individuals from getting tested.
The role of genetics and conventions in Alzheimer’s disease
Genetics has a role to play in Alzheimer’s disease. Researchers have found that it is due to an autosomal dominant mutation in the three genes: APP gene, presenilin 1 (PSENI), and presenilin 2 (PSEM2). This has been identified as the cause of early-onset Alzheimer’s disease or the presenile form. The late-onset form of Alzheimer’s disease is more common and is shown to be linked to ApoE ɛ4. It was seen that the senile and presenile forms of Alzheimer’s disease is more common and still, the identification of the condition is mainly done by trained physicians based on the clinical findings.
For most individuals, there is no single test to give a diagnosis for Alzheimer’s, and thus a combination of cognitive tests, neurologic exams, and family medical history all help in evaluating a person’s mental functions. MRI scans and blood tests are done to exclude any other conditions. However, specialist opinion can yield accurate results most of the time, but individuals with this condition, do not frequently seek specialist help, thus the disease goes under-detected and error rates may be higher.
Modern Diagnosis Methods in Alzheimer’s Disease
Positron emission tomography (PET) scans: It can reveal the abnormal protein clusters which accumulate due to Alzheimer’s disease in people’s brains. Thus, the progressive accumulation of beta-amyloid or Aβ peptide in so-called neuritic plaques are a hallmark of the disease, and a possible contributor to cell death, which can be evaluated from the PET scan.
Biomarkers: Research has paved the path for the identification of new biomarkers which could help with the early identification of Alzheimer’s disease. The role of biomarkers also includes the monitoring of therapeutic response and helps with differential diagnosis. It has been known for a long that the accumulating amyloid breakdown products slip off the brain into the central spinal fluid and then into the bloodstream. Thus, amyloid-related molecular biomarkers are CSF Aβ as well as amyloid PET. The most commonly used amyloid imaging agent is PiB which binds to Aβ aggregates with high affinity and is able to differentiate normal individuals with those having Alzheimer’s disease.
P-tau levels in CSF: This is a reflection of neuronal injury or neurodegeneration. It represents disease progression. High levels of P-tau is characteristic to Alzheimer’s disease than other dementia. ApoEɛ4 too correlates with different patterns of tau deposition.
NFL in CSF: NFL is the light subunit of neurofilament and the main axonal cytoskeleton protein. The presence of NFL chain protein in the CSF indicates axonal damage. It indicates neurodegeneration which is also present in Alzheimer’s disease.
Plasma biomarkers: Blood-based biomarkers are a useful tool to enhance the screening possibility, making it a very accessible tool for clinical diagnosis. Plasma biomarkers prevent the need for lumbar puncture which is an invasive procedure. It also prevents unnecessary amyloid PET scans. The candidate blood biomarkers include plasma levels of neurofilament light (NFL) chain protein, tau protein, and Aβ. These biomarkers give a reliable estimate of the presence of brain amyloids and neurodegeneration. Then the use of fully automated immunoassays helps to accurately detect the plasma levels.
Treatment Methods for Alzheimer’s Disease
The pharmacotherapeutic approaches to Alzheimer’s disease is classified as symptomatic and disease-modifying therapies (DMTs). Symptomatic treatments improve the symptoms of agitation, psychosis, and sleep disturbance. DMTs focus on interventions for the tau and amyloid cascade. Aβ accumulation is the main target of most drugs.
Symptomatic Treatment: Neuropsychiatric symptoms (NPS) are the main feature in Alzheimer’s disease which is present in all stages of the disease. In the pre-clinical stages, these symptoms could progress to dementia. In the initial stages, there is mild behavioural impairment. Psychotic drugs help in the treatment of such behavioural and psychological symptoms.
Acetylcholinesterase inhibitors: When individuals have Alzheimer’s disease, cognition is impacted. It occurs due to diminished cholinergic synaptic activity. The acetylcholinesterase inhibitors used as medicines include donepezil, galantamine, and rivastigmine. These drugs help to delay the onset of Alzheimer’s disease.
Disease-modifying therapies: These therapies help in the accurate diagnosis at the preclinical and pre-dementia stages. The development of DMTs helps to attenuate decline and preserve cognitive and functional capacity.
Amyloid-based Therapies: This is the use of anti-amyloid compounds to clear the Aβ peptide from the brain parenchyma. The most recent medication used is aducanumab, which is an antibody that binds to soluble and insoluble Aβ.
In conclusion, the novel diagnostic methods and treatment of Alzheimer’s disease is paving a new path for Alzheimer’s patients