Alzheimer's disease is the most common form of dementia. It is an incurable neurodegenerative disorder marked by a long preclinical period of progressive cognitive and behavioral impairment that significantly interferes with social and occupational functioning. Approximately 55 million adults worldwide are affected by Alzheimer's disease. Early diagnosis and management of Alzheimer's disease allow patients to maintain higher cognitive levels and functional ability.
Current clinical practice guidelines from the Alzheimer’s Association state that, in order to render a diagnosis of MCI owing to Alzheimer's disease, the patient's cognition upon assessment must be outside the normal range of function for their age and educational background but not sufficiently impaired to constitute dementia.
Cognitive decline can be documented by history from the patient, which is ideally corroborated by someone who closely observes the patient on a regular basis or upon observation by the clinician, per the same guidelines.
The Alzheimer’s Association guidelines also note that impairment can involve one or more cognitive domains. The clinician determines whether memory is prominently impaired or whether the impairments in other cognitive domains predominate, such as spatial or language impairment. Typically, memory is the most common domain involved among patients who subsequently progress to Alzheimer's dementia.
According to the Alzheimer’s Association Clinical Practice Guidelines, a diagnosis of MCI due to Alzheimer’s disease requires that basic activities of daily living (eg, dressing, eating, bathing) remain preserved. While there might be mild impairment in more complex functional tasks, such as managing finances or planning events, significant functional decline, especially in basic daily activities, would most likely suggest dementia rather than MCI.
Learn more about the presentation for Alzheimer's disease.
Depression is a significant consideration in the early diagnosis of Alzheimer's disease. Further, it has been shown to be a sign of early Alzheimer’s disease. The clinical manifestations of depression overlap with those of Alzheimer's disease. The term pseudodementia refers to the appearance of cognitive dysfunction owing to depression.
Depression in patients with Alzheimer's disease appears to differ from depression in elderly patients without cognitive impairment. Depression in Alzheimer's disease more often features motivational disturbances (eg, fatigue, psychomotor slowing, and apathy), whereas depression in patients without cognitive impairment tends to feature mood symptoms (eg, depressed mood, anxiety, suicidality, and sleep and appetite disturbances).
Hypoglycemia, hearing impairment, and alcohol or drug abuse have been linked to cognitive decline and increased risk of dementia. However, they generally are not regarded as signs of Alzheimer's disease.
Learn more about diagnostic considerations in Alzheimer's disease.
Patients with MCI are at higher risk of developing Alzheimer's disease and other dementias than patients who do not have MCI. Vitamin D deficiency has been associated with cognitive impairment and an increased risk of MCI, although findings are not entirely consistent. For example, some research suggests that individuals with severe vitamin D deficiency have an increased risk of developing MCI compared with those with normal levels while other studies have not found a significant association, particularly among individuals with normal cognition or existing MCI. The Alzheimer’s Association and other research bodies continue to explore vitamin D as a possible modifiable risk factor, but causality has not been firmly established.
In contrast, mild to moderate alcohol consumption, bilingualism, and hearing aid use have been associated with protective cognitive effects or reduced risk of cognitive decline in some studies.
Learn more about risk factors for Alzheimer's disease.
Cholinesterase inhibitors (donepezil, rivastigmine, and galantamine) are commonly prescribed early in Alzheimer’s disease to help slow the progression of cognitive and functional decline and improve symptoms. However, these agents do not address the underlying cause of neuronal degeneration, and their effects are symptomatic rather than disease-modifying.
Antidepressants are commonly prescribed to treat mood and behavioral symptoms in patients with Alzheimer's disease. However, available evidence does not support their use to delay cognitive decline. In fact, recent observational studies in dementia populations, particularly those using SSRIs, have shown antidepressants might be associated with faster cognitive deterioration and higher risks of severe dementia, fractures, and mortality.
Antipsychotics (both typical and atypical) have been used to manage behavioral symptoms in Alzheimer’s disease, such as agitation, psychosis, or hallucinations, but they are not used to delay cognitive deterioration. Further, in 2005, the US Food and Drug Administration issued a black box warning on the use of atypical neuroleptics in the treatment of secondary symptoms of Alzheimer's disease because of increased risk for death or stroke. More recent studies have shown that antipsychotic use in dementia may also be associated with elevated risks of pneumonia, venous thromboembolism, kidney injury, heart failure, fractures, and notably, accelerated cognitive decline, with the most serious harms occurring within the first 3 months of treatment.
Learn more about the treatment of Alzheimer's disease.
Engaging in mentally stimulating activities might help support cognitive function in patients with MCI or early Alzheimer’s disease. While clinical evidence is still evolving, these interventions are widely recommended by organizations like the Alzheimer’s Association as nonpharmacologic strategies to promote brain health. Cognitive training programs have shown modest benefit in some studies, particularly when used alongside pharmacologic treatment, though results vary and are not considered disease-modifying.
Behavioral interventions like environmental modifications and caregiver-led strategies are effective for managing specific symptoms, but there is no strong evidence to support utilizing them as a monotherapy for preserving cognition in Alzheimer’s disease.
EPA and DHA are omega-3 fatty acids that have been studied for potential neuroprotective effects. However, trials in Alzheimer’s disease have not shown clear or significant clinical benefit.
There is growing interest in dietary patterns like the Mediterranean and MIND diets for their potential to support cognitive health. However, no specific diet alone is currently recommended for Alzheimer's disease, and dietary changes are not considered nonpharmacological interventions for cognitive decline.
Learn more about approach considerations for Alzheimer's disease.
Editor's Note: This article was created using several editorial tools, including generative AI models, as part of the process. Human review and editing of this content were performed prior to publication.
