Mild cognitive impairment, or MCI, is used to describe the early stages of memory loss often proceeding or associated with Alzheimer’s disease. This causes cognitive and memory problems that are significant enough to be noticed by the patient. A diagnosis of mild cognitive impairment doesn’t always mean the person will develop Alzheimer’s. The condition can remain stable or even improve (revert). There are two primary types of mild cognitive impairment; amnestic MCI and nonamnestic MCI. It is important to note that some medications or brain injuries, just as TBI, may also cause cognitive symptoms, so discuss any medications you’re taking with your doctor before diagnosis [1].
Symptoms
Amnestic MCI is more commonly recognized because it results in loss of memory. Someone with amnestic MCI may forget information that they previously had no trouble recalling. The ability to keep track of appointments, names, recent events, and car keys is negatively impacted with this form. Note that occasional forgetfulness, occurring once per week or less often, is normal and should not be cause for concern.
Nonamnestic MCI can be thought of a cognitive impairment that affects procedural or non-declarative memory. Decision making, planning, and executing sound judgement are examples of cognitive tasks that do not require memory, but will decline with nonamnestic MCI.
Diagnosis criteria
Mild cognitive impairment should only be diagnosed by your physician. If they are unable to confirm a diagnosis of MCI using cognitive tests alone, then biomarkers will be measured. According to the Mayo Clinic, the following 5 criteria are used to determine whether you have this disorder:
- Perhaps the most obvious criteria is whether you are experiencing problems with memory or another mental function. Some signs of memory problems include trouble remembering the date, your appointments, difficulty concentrating, and repeating yourself without realizing it. Other specific signs include trouble making and executing plans, following directions, and decision-making. Ideally, someone close to you will make the same observations and bring them to the attention of your physician.
- Your cognitive abilities decrease over time. Perhaps you’re unable to perform your work as quickly as you used to, or your writing style is less eloquent than it used to be. While it’s normal for someone in their 70s to think more slowly than someone under 30, a decrease in your abilities over time could indicate mild cognitive impairment when accompanied by other symptoms.
- Overall, you can still function independently and your daily activities aren’t affected. This guideline helps clinicians differentiate between MCI and more severe brain problems. Many people learn to work through their memory challenges with scheduling tools or reminder apps on their phone. Because of these adaptations, they can still function somewhat normally. Or, you might believe that you are still functioning well but your friends and family disagree. If there is any discrepancy between your perceptions and theirs, then it’s a good idea to address the situation with your doctor.
- You’re performing below expected for your age and education level on mental status tests. Mental status tests are extremely common. The mini mental status exam (MMSE) is perhaps the most common test. As mentioned previously, minimal cognitive decline is normal and expected as we age. In addition, your education level has some effect on the way your mind changes as you age. Studies show that people with more education tend to retain their cognitive abilities as they age. The effect boils down to practice – the longer you’re studying and writing, the more practice your brain has had in thinking through problems. An ideal mental status test will “control” for age and education level. This is just a scientific way of saying that your scores will be compared to people in the same age group.
- You don’t have dementia. Perhaps you have some memory loss and you’re relying more on notes to live independently, but your problems aren’t acute enough to warrant a diagnosis of Alzheimer’s or dementia. This is mild cognitive impairment in a nutshell. As such, this final requirement is more of a guideline to be consulted when you meet the first four requirements for MCI diagnosis [2].
Risk factors
There are 4 risk factors associated with later development of mild cognitive impairment. The first one is age. Age as a risk factor is purely correlational and not causal – since life expectancy has increased, there is a higher incidence of MCI and Alzheimer’s disease today than there was 100 years ago.
A second risk factor is poor smelling ability. It turns out that smell is linked very closely with the structures in our brain that create new memories (the hippocampus). Losing your sense of smell over time could be due to changes in the sensory organ itself (known as the olfactory bulb) or loss of neurons in the hippocampus.
Your stride says a lot about the state of your brain. It turns out that people who later develop MCI tend to walk slower than their healthy peers [3].
APOE genotypes determine much of our risk. The APOE gene is a common cause of cognitive decline and each person has two copies of it. Each copy represents 1 of 4 possible versions for the gene. Someone with a copy of APOE1 from their mother and APOE3 from their father would describe their genotype as E1/E3. APOE4 is a variety of the gene that is particularly culpable for Alzheimer’s dementia and MCI. If you have just one copy of the gene, your risk increases 2-3 fold. People who have the E4/E4 genotype have an increase in risk of up to 12 times that of their healthy peers [4].
Can I reduce my risk of mild cognitive impairment?
If you’re like most people, you probably can’t do much to change your age or the genes you were born with. It’s important to understand that a diagnosis of mild cognitive impairment does not guarantee that you will develop Alzheimer’s disease later on. The incidence of Alzheimer’s following MCI diagnosis is about 5-20% . Some medical conditions contribute to your risk – hypertension, diabetes, strokes, and heart problems often co-occur with MCI. It follows that the most practical way to reduce your risk is to exercise regularly, maintain a healthy blood sugar level, and avoid smoking or drinking [5].
References
[1] Mild Cognitive Impairment (MCI). (n.d.).
[2] Mild cognitive impairment (MCI). (2018, August 23).
[3] Lipnicki DM;Crawford J;Kochan NA;Trollor JN;Draper B;Reppermund S;Maston K;Mather KA;Brodaty H;Sachdev PS; ; (n.d.). Risk Factors for Mild Cognitive Impairment, Dementia and Mortality: The Sydney Memory and Ageing Study.
[4] What APOE Means for Your Health. (n.d.).
[5] How can someone minimise the risk of mild cognitive impairment and dementia? (n.d.).