What are the symptoms of Alzheimer's disease?
Pro Research Analysisby 
Searched over 200M research papers
Consensus Meter
Symptoms of Alzheimer's Disease
Early Symptoms: Memory Loss and Cognitive Impairment
Memory loss is one of the earliest and most recognizable symptoms of Alzheimer's disease (AD). In late-onset AD (LOAD), memory loss can begin as early as 12 years before a clinical diagnosis is made. Cognitive impairment, particularly in areas such as semantic memory and conceptual formation, is also an early indicator of the disease. These cognitive deficits often manifest as difficulties in remembering recent events, solving problems, and making decisions.
Neuropsychiatric Symptoms: Depression, Apathy, and Aggression
Neuropsychiatric symptoms (NPS) are core features of AD and can appear in the very early stages of the disease, even during the mild cognitive impairment phase. Common NPS include depression, apathy, aggression, and psychosis. Depression and apathy are particularly prevalent, with apathy being the most common neuropsychiatric symptom in AD. These symptoms are associated with specific brain regions, such as the anterior cingulate cortex and the prefrontal cortex, which are often damaged in AD .
Behavioral Disturbances: Eating and Sleeping Disorders
AD patients frequently experience behavioral disturbances, including eating and sleeping disorders. These non-cognitive symptoms are often linked to the broader neurodegenerative processes affecting the entire brain, not just the memory centers. Such disturbances can significantly impact the quality of life for both patients and their caregivers, contributing to increased caregiver stress and early institutionalization.
Advanced Symptoms: Neurological and Motor Impairments
As AD progresses, patients may develop more severe neurological and motor impairments. In the moderate dementia stage, cognitive deficits become more pronounced, affecting various cognitive domains and leading to increased dependence on caregivers. In the late stages of AD, patients often exhibit complete dependence and may develop additional neurological disturbances such as myoclonus, disturbed gait, and rigidity.
Atypical Presentations: Logopenic Aphasia and Posterior Cortical Atrophy
While the typical presentation of AD involves progressive memory impairment, atypical forms of the disease are increasingly recognized. These include logopenic aphasia, behavioral variant AD, posterior cortical atrophy, and corticobasal syndrome, which are more common in younger patients with early-onset AD. These atypical presentations can complicate diagnosis and require clinicians to be aware of the diverse manifestations of AD.
Conclusion
Alzheimer's disease presents with a wide range of symptoms that evolve as the disease progresses. Early symptoms primarily involve memory loss and cognitive impairment, while neuropsychiatric symptoms such as depression, apathy, and aggression are also common. Behavioral disturbances, including eating and sleeping disorders, further complicate the disease. Advanced stages of AD are marked by severe cognitive and neurological impairments, and atypical presentations can pose additional diagnostic challenges. Understanding these symptoms is crucial for early diagnosis and effective management of the disease.
Sources and full results
Most relevant research papers on this topic