Alzheimer’s disease (AD) is a chronic debilitating disease, particularly for old people. It is the most common type of dementia accounting for roughly 70% of total cases. AD is broadly classified into two categories: early or familial AD; and late-onset AD or sporadic AD. Out of the two categories, the latter covers around 90% of the cases. AD is the fifth major cause of mortality worldwide. According to the latest figures, AD contributes to 60-80% of dementia-related diseases in the world with no known cure, in turn creating a high social burden on both patients and their caregivers. AD is also more common among women than men.
Decades of research emphasize specifically, the role of the hyperaccumulation of fragment beta-amyloid (Aβ) peptides and hyperphosphorylated tau protein aggregation in the brain behind the pathogenesis of AD. It is considered a secondary tauopathy or pathogenesis due to tau proteins. The combined toxic effect of Aβ and hyperphosphorylated tau damages neurons and synapses in the brain. Short-term memory loss, one of the initial symptoms and hallmarks of AD, occurs due to the loss in the plasticity of neuron synapses.
The common symptoms are:
Often hallucination and olfactory or sense of smell disturbances are also seen in patients. Degeneration initiates in the entorhinal cortex and hippocampus region of the temporal lobe of the brain. This hippocampus region is an important area of operation for memory and learning functions. The picture worsens when neurodegeneration extends to the amygdala, cingulate gyrus, and thalamus of the brain.
The quality of life in patients after incurring AD is of the utmost importance. In the middle stages of the disease, patients lose the ability to communicate properly and make judgments. This decline in cognitive functions changes the personality of the patients as they might lose the ability to recognize their loved ones.
The early diagnosis of AD is critical to seeking symptomatic prophylaxis. Early diagnosis is difficult considering the slow progression of AD. AD has clinical stages ranging from mild cognitive impairment (MCI) to severe dementia according to National Institute on Aging–Alzheimer's Association (NIA–AA). The clinical symptoms detection by the clinician is followed by laboratory examination. The laboratory techniques for determining the disease are non-invasive diagnostic imaging such as PET scan and evaluation of biomarkers in CSF and serum.
While there have been advances in both therapeutics and translational research on AD, unfortunately till now, there are no curatives for AD. The treatment relies on lifestyle modifications such as the Mediterranean diet, physical exercise, and vitamin D supplements. Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet is effective in preventing all types of dementia. Cholinesterase inhibitors are typically used for symptomatic management of AD. Cholinesterase inhibitors include drugs like donepezil, galantamine, rivastigmine, and memantine. Oxidative stress is involved in AD pathophysiology so vitamin E is also used in its treatment.
Some emerging treatment strategies in the form of monoclonal antibody-based precision therapy and JNK or specific kinase inhibitor therapies are upcoming. Integrative treatment options such as aromatherapy, music therapy, and engaging patients in both physical and meaningful activities can supplement the well-being of patients along with pharmacological interventions. Taken together, these interventions are helping us better manage this debilitating disease.