Dementia is the loss of cognitive function affecting a patient’s memory, problem-solving abilities, and reasoning that interferes with their daily functioning. The risk of dementia increases as a patient ages, from 1.7% in patients 65–74 to 13.1% in those over the age of 85. This poses a significant public health concern as the population continues to age with the number of Americans over the age of 65 expected to reach 82 million by 2050. So, what do clinicians need to know about the cognitive deficits in Alzheimer’s disease?
The cost of Alzheimer’s disease
While there are many different causes of dementia, Alzheimer’s dementia accounts for an estimated 60–80% of cases. The remainder are attributed to causes such as:
- Frontotemporal dementia
- Lewy body dementia
- Vascular dementia
A diagnosis of dementia places significant emotional and financial stress on caregivers, as well as the healthcare system. It is estimated that in 2023, dementia-related care in the United States was 345 billion dollars. This highlights the need for clinicians to identify at-risk patients, diagnose those affected, and provide effective treatment options for those affected.
Related: Alzheimer’s Disease and Cognitive Deficits
Understanding the subtypes of dementia and neurocognitive disorders
The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) has developed criteria to differentiate dementia/neurocognitive disorders into three subtypes:
- Delirium
- Mild neurocognitive disorders
- Major neurocognitive disorders
Delirium is a disturbance in attention and awareness that develops over a relatively short period of time (hours to days). It can fluctuate in severity throughout the course of the day. The diagnosis requires evidence indicating the condition is secondary to an underlying medical condition, substance intoxication or withdrawal, toxins, or multiple other etiologies.
Mild neurocognitive disorder is a modest decline in cognitive function affecting one or more cognitive domains. These may include complex attention, executive function, learning and memory, language, perceptual-motor, or social cognition. The cognitive decline should be documented by standardized neuropsychological testing. This level of cognitive decline does not interfere with the patient’s independence in everyday activities but may require increased effort, compensatory strategies, or special accommodations to maintain independence.
Major neurocognitive disorder identifies a severe decline in cognitive function affecting one or more cognitive domains as documented on standardized neuropsychological testing. However, unlike mild disorders, a major neurocognitive disorder interferes with the patient’s independence in daily activities. It results in the need for assistance, at a minimum, with complex activities of daily living such as paying bills or managing medications.
When considering mild or major neurocognitive disorders, rule out delirium and other mental disorders as a cause of cognitive impairment. Additionally, clinicians must be able to distinguish normal age-related changes in cognition versus pathologic declines.
Differences between age-related cognitive deficits and dementia
Experiencing difficulties with memory loss can be related to the normal aging process. However, when they become problematic and affect daily activities and the ability to maintain independence, these cognitive deficits may be a result of dementia.
In age-related memory loss, patients will be unable to remember specific details regarding conversations or events that occurred a year ago. They may also occasionally forget the name of an acquaintance or misplace items but are able to find them after retracing steps. These changes can result in difficulty finding the right word or remembering what day of the week it is.
Dementia, on the other hand, results in difficulties recalling specific details of a recent conversation or event and remembering the names of family members. Dementia-related changes cause significant impairments in speaking or writing, confusion with time and place, and the inability to retrace steps to find lost items. This level of impairment often raises concerns with friends and family, but the patient is unaware of the issue.
Risk factors for Alzheimer’s disease
The development of Alzheimer’s disease is multifactorial. Various risk factors have been identified that contribute to the development of Alzheimer’s disease. These include modifiable factors and nonmodifiable risk factors.
- Age. Most cases of Alzheimer’s disease are diagnosed after the age of 65. The risk of developing Alzheimer’s disease doubles every 5 years after the age of 65.
- Family history. The individual risk of developing Alzheimer’s disease is increased in patients with a family history of this disease. Additionally, this risk increases with the number of affected family members.
- Genetics. Various genetic abnormalities can predispose a patient to the development of Alzheimer’s disease. The most supported abnormality is APOE e4 in which having one allele increases the risk of Alzheimer’s disease and predisposes patients to an even further risk when two e4 alleles are carried.
- Modifiable risk factors. Inadequate sleep, smoking habits, hypertension, and diabetes can further place patients at risk of developing Alzheimer’s disease.
Non-pharmacologic treatment options
The use of non-pharmacologic treatments can help patients reduce cognitive deficits, remain independent longer, and improve their quality of life. These treatments can include memory training, psychosocial activation, and physical exercise programs.
Cognitive therapies are ideal for patients with mild to moderate Alzheimer’s disease. They work by stimulating the mental abilities of the individual. These can include various activities like arithmetic problems, exercises requiring images to be remembered and recognized, and word/puzzle activities. Reality orientation training can help elderly patients maintain their sense of time and space.
Addressing other conditions that can affect the mental facilities of elderly patients is an important aspect of non-pharmacologic treatment. This can include cognitive behavioral therapy, behavioral management therapy, and psychotherapy to manage co-existing depression and behavioral issues.
Exercise programs not only help to improve cognitive functions, but can help improve mobility, balance, and strength, helping patients stay independent longer.
Aromatherapy, pet therapy, music therapy, and meditation can provide benefits for behavior issues associated with dementia. Caregiver support groups can help assist family members with how to care for someone with dementia.
Pharmacologic treatment of Alzheimer’s disease
Two general classes of medications are available for the treatment of Alzheimer’s disease. A new class of disease-modifying drugs are also now available.
- Cholinesterase inhibitors. The mechanism of these drugs increases acetylcholine within the synaptic terminals by inhibiting the enzyme, acetylcholinesterase, responsible for the metabolism of acetylcholine. Donepezil and Rivastigmine are approved for mild, moderate, and severe dementia, while galantamine is approved for mild to moderate.
- Glutamine antagonists. By blocking glutamine receptor activation, Memantine can reduce oxidative stress and neuronal damage caused by excessive stimulation of the NMDA receptor. Memantine is approved for moderate to severe Alzheimer’s disease.
- Disease-modifying agents. Aducanumab and lecanemab reduce the amyloid-beta plaque burden by binding with fibrillary conformations of amyloid-beta plaques in the brain.
Conclusion
Alzheimer’s disease is the most common form of dementia. It leads to significant economic and psychological impacts on patients and their families. Early diagnosis and treatment can make significant impacts on delaying the progression and maintaining the independence of those affected. A combination of non-pharmacologic and pharmacologic treatments can improve the management of cognitive deficits from Alzheimer’s disease.
