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Types of Memory Loss and Dementia

Updated: Mar 4, 2020

There are so many different types of memory loss. There are normal brain changes as we get older. There are reversible forms of memory loss. And there is memory loss due to medical or brain conditions. In another article, I talk about normal brain changes as we get older, and about reversible forms of memory loss.

Here I'm going to talk about memory loss due to brain conditions. There are so many types, and each type affects a person differently. If you or a loved one has a brain condition, I think this information helps to understand how it affects them and how it may affect them in the future.

Alzheimer's Disease is the most common type of memory loss in people over age 65. There are forms of Alzheimer's Disease that have no symptoms and no memory loss, just the brain changes associated with Alzheimer's. These people just have a positive amyloid PET scan, and may be eligible for a trial for new medications. We call them preclinical Alzheimer's Disease, or presymptomatic Alzheimer's Disease. In typical Alzheimer's Disease with symptoms, it results in changes in the temporal and parietal lobes. The temporal lobe is important for memory, and the parietal lobe is important for language. So a person with Alzheimer's Disease may not be able to remember what happened despite reminders, need excessive reminders, repeat themselves, have trouble understanding others, expressing themselves, or become irritable because their brain is not able to handle new information. They may get lost driving, begin to have issues with focusing or judgement to the point that it is best for them not to drive. They may be at risk for dehydration and syncope (passing out) due to forgetting to drink water, have balance issues, or urinary incontinence because they forget to go to the bathroom. A person with severe Alzheimer's Disease usually does not talk unless spoken directly to, has trouble getting up from a chair, and may sleep most of the day. Typical Alzheimer's Disease may last a total of 20 years from symptom onset to passing away, usually 5 years in the mild stage, 10 years in the moderate stage, and 5 years in the severe stage.

There are forms of Alzheimer's Disease that start earlier in life. They are called early-onset Alzheimer's Disease, and start before the age of 65. Instead of involving the temporal lobe like typical Alzheimer's Disease, usually involve the frontal and parietal lobe functions. People with early-onset Alzheimer's Disease may not have trouble remembering, but more trouble with expressing themselves, seeing, or understanding. They may have trouble focusing or multitasking. Early-onset Alzheimer's Disease usually progresses faster than typical Alzheimer's Disease, and may be related to a gene like APOE4.

Alzheimer's Disease may also have atypical forms. Frontal lobe Alzheimer's Disease may affect the frontal lobe functions more than the temporal lobe, and people may have trouble focusing, multitasking, controlling their negative emotions, disinhibition, and poor judgement. Posterior Cortical Atrophy is a form of Alzheimer's disease that affects the occipital and parietal lobe function, mainly resulting in trouble seeing objects and visual perception. Logopenic Primary Progressive Aphasia is a form of Alzheimer's disease that primarily affects the parietal lobe, resulting in difficulty understanding long sentences and trouble expressing themselves.

The second most common type of Dementia is Mixed Cognitive Impairment. This usually happens in people over age 65. They have some signs of typical Alzheimer's Disease, but also memory loss due to Vascular Cognitive Impairment. So, this is a mix of neurodegeneration (brain cell death) due to Alzheimer's, and lack of blood flow due to vascular disease. This type is common in people with many years of high blood pressure, high cholesterol, diabetes, or smoking. Vascular Cognitive Impairment affects the connections in the brain, and frontal lobe function. This results in difficulty focusing and multitasking, but also poor judgement, inability to control negative thoughts, feelings, or actions, and impulsivity. People with Vascular Cognitive Impairment or Mixed Cognitive Impairment may be particularly rude to the people they are closest with, and it is because they have trouble controlling their negative words or actions. But medication can help with these symptoms. Mixed Cognitive Impairment usually progresses faster than typical Alzheimer's, but can be slowed down by controlling blood pressure, cholesterol, blood sugar, and not smoking. In fact, a recent trial showed that people over age 50 who maintained their systolic blood pressure less than 120 had a lower risk of cognitive impairment. So it is important to know your blood pressure. I usually recommend getting a blood pressure machine and checking it every morning for 3 days. If it is over 120/80, even if it is 125/80, I recommend talking with your primary care physician to lower the blood pressure. Some medications for blood pressure may worsen cognition like the beta-blockers (metoprolol, carvedilol, propranolol), so I usually recommend blood pressure medication other than those.

Lewy Body Disease and Parkinson's Disease Dementia are also somewhat common, and they affects frontal and parietal lobe functioning, as well as nerves in organs throughout the body. These people do not have language issues, and reminders usually help their memory. They usually begin with constipation, progressing to difficult anxiety or depression, and then needing a lot of time to process information. Gradually their body becomes tense and rigid, and they have a lot of body pain. They may have trouble sleeping. Sometimes people Lewy Body or Parkinson's Disease Dementia do not have tremor, but rather rigidity, pain in their body, and slowness of movement. We do not know (?) about the rate of progression of these diseases, but they happen over several (5-20) years.

Chronic Traumatic Encephalopathy is a type of neurodegeneration associated with concussions or traumatic brain injuries, usually in people who have had multiple head injuries in previous years, such as in football players. This affects the frontal? and movement? systems of the brain, so a person initially has severe depression or anxiety, which progresses into trouble focusing, parkinsonism, and suicidality.

Primary Progressive Aphasia is a class of neurodegenerative disease that affect a person's language abilities first. I talk about Logopenic Primary Progressive Aphasia above because it is usually caused by Alzheimer's Disease. Nonfluent/Agrammatic Primary Progressive Aphasia affects the part of the brain associated with getting words out, and results in trouble speaking, with the person leaving out words in their speech. Nonfluent/Agrammatic Primary Progressive Aphasia is usually associated with parkinsonism. Semantic Primary Progressive Aphasia affects the part of the brain that stores the knowledge of what words mean. So, a person with Semantic Primary Progressive Aphasia will not understand some words, particular those we don't use very often, and may say things that don't make sense. This type is usually associated with Frontotemporal Dementia and may include those symptoms.

Frontotemporal Dementia is a neurodegenerative disease that affects the frontal lobe function so severely that people have trouble interacting with others, controlling their emotions. Because of their brain changes, people with these changes may be sexually inappropriate with others, lack empathy for the emotions of others. They have trouble focusing and multitasking.

Limbic-predominant TDP43-associated Encephalopathy is a neurodegenerative disease that affects memory and later frontal lobe function, but progresses very slowly. This disease was just discovered in 2019, so we know very little about it. It may be a very common form of memory loss in people over age 85 and progresses very slowly.

Even though these diseases are neurodegenerative, meaning brain cells shrink and die over time, there are usually ways to help the symptoms. For Alzheimer's Disease, we do therapies to help slow it down. Once we have even more therapies for Alzheimer's Disease, we will likely have better treatments for the other types of Dementia. There are also research trials for every type of Dementia described above.

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