Challenges in Brain Drug Delivery for Neurodegenerative Disorders and Recent Trends: A Review

Age-related disorders known as neurodegenerative illnesses are defined by uncontrolled neuronal loss that gradually impairs brain function. The majority of age-related neurodegenerative disorders are caused by dementias, in particular. Nowadays, the neurodegenerative disorders are not limited to age and are reported in all age groups. The drug delivery to treat the neurodegenerative disorders is challenging due to the presence of the blood-brain barrier (BBB).

A critical literature review has been conducted across databases such as Scopus, Embase, Cochrane, and PubMed. Blood-brain barrier, neurodegenerative disorders, novel drug delivery system, and targeted drug therapy were the search terms.

Neurodegenerative Diseases (NDD) impact the peripheral nervous system, nerve cells, muscles, and the nerve-muscle junction. This term broadly encompasses cognitive disorders, such as Alzheimer's disease, Lewy body dementia, frontotemporal dementia, and vascular dementia. Additionally, other neurodegenerative conditions such as multiple sclerosis, amyotrophic lateral sclerosis, Parkinson's disease, and spinocerebellar ataxias predominantly impair motor system function and nerves in the limbs. The existing therapeutic approaches to treat neurological diseases exhibit limited efficacy due to the BBB. This highly selective semipermeable membrane permits vital nutrients to enter the brain while blocking the potentially harmful toxins. It makes it very challenging to get medications into the brain. There are several effective approaches to deliver drugs to the brain (nanocarrier systems, intranasal administration, and focused ultrasound) to address the limitations of conventional treatments.

This review discusses neurodegenerative disorders, brain anatomy/physiology, barriers to drug delivery, and strategies to overcome these limitations.