Alzheimer’s disease (AD) is a major type of dementia and neurodegenerative disease, characterized by memory loss and cognitive decline. Over decades, significant efforts have been dedicated to finding its cause, pathogenic mechanisms, biomarkers for early detection, and clinical trials for its treatment. Earlier approved drugs mainly ameliorated the symptoms of AD, until recent years when two drugs targeting amyloid-beta (Aβ) protein were approved to slow down the progression of the disease. This review article encompasses the history of drug development in treating AD and clinical trials that failed and succeeded. Clinicaltrials.org website was systematically searched and screened for randomized controlled trials with results posted in the past 10 years. Among the 3,388 AD clinical trials, 211 interventional studies registered under AD have met eligibility. This review includes the interventional targets for drug discovery such as Aβ, tau, neurotransmitter receptors, neuroinflammation, multi-target studies, repurposing pharmacological agents, non-pharmacological interventions, and clinical therapy development for the neuropsychiatric symptoms of dementia. Current clinical trials are ongoing and no results are available as of yet. With the vast choices of drug targets that have been investigated, this review aims to present some insights into future AD drug design and trials and contribute to our ongoing efforts to find the cure.

Receptor tyrosine kinases (RTKs) are known to perform versatile roles in disease landscapes, which determine the fate of the cell. Although much has been discussed from the perspective of proliferation, this review focuses on the impact of RTK-mediated signaling and its role in cytoskeletal degradation, the penultimate stage of cellular degeneration. In the case of degenerative diseases such as Alzheimer’s disease (AD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS), Parkinson’s disease (PD), age-related macular degeneration (AMD), and type 2 diabetes mellitus (T2DM), RTK signaling has been reported to be perturbed in several studies. The implications of downstream signaling via these receptors through canonical and noncanonical pathways alter the status of actin filaments that provide structural integrity to cells. Degenerative signaling leads to the altered status of rat sarcoma (Ras), Ras homologous (Rho), Ras-related C3 botulinum toxin substrate (Rac), and cell division control protein 42 (Cdc42), the best-characterized components of the cytoskeleton remodeling machinery. RTKs, along with their diverse adaptor partners and other membrane receptors, affect the functionality of Rho family guanosine triphosphate hydrolases (GTPases), which are discussed in this review. To conclude, this review focuses on therapeutic strategies targeting RTKs and Rho GTPase-mediated pathways that can be more effective due to their combined multifactorial impact on neurodegenerative cascades.

Life is the highest form of adaptation to the environment which is based on energy metabolism. To maintain life, the neuromuscular system must constantly interact with the environment. The striatal muscles are the main energy consumer and their access to energy fuel is mainly limited by the brain’s needs. In the state of wakefulness, the brain must continuously process streams of sensory signals and respond to them with motor actions. At the same time, the brain to be efficient must memorize the sensory-movement relationships. Brain memory networking requires additional energy allocation, and due to limited systemic energy resources, the processes of memorization are completed during the sleep phase when the inactive muscular system allows allocating the energy fuel to the brain functions such as memory trace formation and the removal of the activity-dependent waste products. Both physiological processes can be completed during sleep only, and consequently, chronic sleep disorder leads to pathological changes in brain functioning and escalation of neurodegenerative processes. Consequently, sleep disorders become the main cause of dementia which is the prodrome of Alzheimer’s disease.