Understanding Alzheimer's Disease

Neurofibrillary tangles are a hallmark pathological feature of Alzheimer’s disease. They form when tau proteins become hyperphosphorylated and aggregate inside neurons, disrupting axonal transport. This leads to neuronal dysfunction and death. Dopamine and serotonin abnormalities are more associated with other neurological disorders, while acetylcholine loss is a consequence rather than the primary pathology.

Neuroimaging allows clinicians to evaluate brain structure, volume, and progression of neurodegeneration. MRI and CT scans help identify cortical atrophy, ventricular enlargement, and hippocampal volume loss. These structural changes assist in diagnosis, monitoring disease progression, and ruling out reversible causes of dementia. Neuroimaging is not limited to tumors or medication effects.

MRI is preferred because it provides high-resolution, three-dimensional images of brain structures, especially the hippocampus. It is superior to CT in detecting early atrophy and subtle changes associated with Alzheimer’s disease. CT is often used initially but lacks the sensitivity needed for detailed assessment.

CT scans can detect cerebral atrophy but struggle to differentiate changes caused by normal aging versus Alzheimer’s disease. MRI offers better contrast and anatomical detail, making it more effective for distinguishing pathological neurodegeneration. This limitation reduces CT’s usefulness for definitive diagnosis and disease monitoring.

Cholinesterase inhibitors increase acetylcholine availability by preventing its breakdown, improving cognitive symptoms. NMDA antagonists reduce excitotoxicity by modulating glutamate signaling. Together, these medications provide modest symptomatic improvement but do not halt disease progression, which reflects the current limitations of Alzheimer’s therapy.

Neurofibrillary tangles initially develop in the hippocampus and medial temporal lobe. These regions are crucial for memory formation, explaining why memory impairment is often the earliest symptom of Alzheimer’s disease. As the disease progresses, tangles spread to association cortices, worsening cognitive decline.

The cholinergic system is most affected in Alzheimer’s disease. Neurons that release acetylcholine degenerate, leading to impaired attention, learning, and memory. This biochemical deficit forms the basis for using cholinesterase inhibitors as a cornerstone of treatment.

Hippocampal atrophy is a classic MRI finding in Alzheimer’s disease. The hippocampus plays a central role in memory processing, and its early degeneration correlates with memory loss. MRI is particularly effective in visualizing this structural change compared to other imaging modalities.

Current Alzheimer’s treatments focus on improving symptoms such as memory loss and confusion. They do not reverse neuronal damage or stop disease progression. This reflects the lack of disease-modifying therapies and highlights the importance of early diagnosis and supportive care.

Memory impairment is the most common early symptom of Alzheimer’s disease. It results from hippocampal and medial temporal lobe involvement. Other symptoms like motor deficits or hallucinations typically occur later or are associated with different neurological conditions.