The Reality of a Late-Onset Dementia Diagnosis
Advanced age is the most significant risk factor for developing dementia. While many associate dementia with individuals in their 70s or 80s, the incidence, or rate of new cases, continues to increase exponentially after age 90. Research from The 90+ Study shows the rate of new dementia cases doubles approximately every 5.5 years, even in nonagenarians and centenarians. The overall incidence rate for those 90 and older is about 18.2% per year. Specifically, it rises from 12.7% per year in the 90-94 age group to 21.2% in the 95-99 age group.
This means that while a person may have enjoyed a lifetime of sharp cognitive health, a new diagnosis in their tenth decade is a distinct possibility. Understanding this is crucial for families and caregivers in distinguishing between normal age-related memory lapses and the more significant symptoms of a neurodegenerative disease.
Common Types of Dementia in the Very Old
In individuals over 80, dementia is often caused by a combination of factors, a condition known as mixed dementia. The most common combination is Alzheimer's disease and vascular dementia. However, other pathologies become more prevalent in this age group.
- Mixed Dementia: The most common diagnosis in those over 80, where pathologies of more than one type of dementia are present.
- Alzheimer's Disease: While still the most common single cause, its presentation can be complicated by other conditions. About half of people with dementia over age 90 may not have the classic brain pathology sufficient to explain their cognitive loss.
- Vascular Dementia: Caused by problems with blood supply to the brain, such as mini-strokes. Its risk is elevated by conditions like high blood pressure and atherosclerosis.
- Limbic-predominant age-related TDP-43 encephalopathy (LATE): A recently identified condition common in older adults that mimics Alzheimer's symptoms.
- Hippocampal Sclerosis: A loss of neurons and scarring in the hippocampus, a brain region critical for memory, which is found more commonly in those over 90.
Risk Factors and Protective Measures
While age is the primary risk factor, other elements can influence the likelihood of developing dementia late in life. Many of these are tied to cardiovascular health.
Key Risk Factors:
- Cardiovascular Issues: High blood pressure, high cholesterol, and diabetes, especially in mid-life, increase dementia risk.
- Genetics: The APOE ε4 allele is a major genetic risk factor for late-onset Alzheimer's disease.
- Hearing and Vision Loss: Uncorrected sensory impairments are associated with a higher risk of cognitive decline.
- Head Injuries: A history of significant traumatic brain injury can be a contributing factor.
- Social Isolation: A lack of social engagement is linked to a higher risk.
Potential Protective Measures: There is no guaranteed way to prevent dementia, but a healthy lifestyle can help reduce risk. Engaging in these habits is beneficial at any age.
- Stay Physically Active: Aim for at least 150 minutes of moderate-intensity activity per week.
- Maintain a Healthy Diet: A diet rich in fruits, vegetables, whole grains, and healthy fats is beneficial for brain health. The National Institute on Aging provides extensive resources on healthy diets for seniors.
- Engage Your Brain: Mentally stimulating activities like reading, puzzles, or learning a new skill can help maintain cognitive function.
- Manage Health Conditions: Effectively manage blood pressure, blood sugar, and cholesterol levels.
- Stay Socially Connected: Regular interaction with family and friends supports brain health.
Recognizing Symptoms vs. Normal Aging
Distinguishing dementia symptoms from typical age-related changes can be challenging, particularly in nonagenarians who may have other health issues. The key difference is often the impact on daily functioning.
| Normal Aging | Potential Sign of Dementia |
|---|---|
| Occasionally forgetting names or appointments but remembering later. | Frequent memory loss that disrupts daily life, especially of recent events. |
| Making occasional errors when balancing a checkbook. | Inability to manage a budget or follow a familiar recipe. |
| Needing help sometimes with new technology or microwave settings. | Difficulty completing familiar tasks at home or work. |
| Getting confused about the day of the week but figuring it out later. | Losing track of dates, seasons, and the passage of time. |
| Vision changes related to cataracts or other eye conditions. | Trouble understanding visual images and spatial relationships. |
| Sometimes having trouble finding the right word. | New problems with words in speaking or writing; repeating oneself. |
Challenges in Diagnosis
Diagnosing dementia in a person over 90 presents unique challenges:
- Co-existing Conditions: Multiple health problems (comorbidities) and medications can cause dementia-like symptoms.
- Sensory Decline: Significant hearing or vision loss can make cognitive testing difficult and inaccurate.
- Lack of Normative Data: There is limited data on 'normal' cognitive function for this age group, making comparisons difficult.
- Functional Disability: It can be hard to determine if functional decline is due to cognitive issues or physical frailty.
Conclusion
Yes, a person can absolutely get dementia at age 90. The risk is substantial, and the incidence continues to climb with each passing year. While Alzheimer's remains a primary concern, the landscape of dementia in the very old is often a complex mix of pathologies. Recognizing the signs, understanding the unique diagnostic challenges, and focusing on heart-healthy lifestyle choices for risk reduction are key components of promoting cognitive health throughout the entire lifespan.
