Dementia is an umbrella term used to describe progressive, degenerative brain syndromes that affect memory, thinking, behavior and emotion. It is not one specific condition or disease but rather, a set of symptoms that affect a person’s ability to perform everyday tasks.
These symptoms vary based on what is causing dementia and what area(s) of the brain are affected by the underlying physiological disorder.
Alzheimer’s is one type of dementia. It is the most well-known and highest-profile, accounting for 40–70% of all dementia diagnoses. Usually affecting people over age 65, Alzheimer’s has a relatively slow disease process with people often surviving for 10–15 years post-diagnosis. It typically impacts our memory first, destroying neurons and their connections in parts of the brain including the hippocampus and the entorhinal cortex. Later in the disease process, Alzheimer’s affects areas of the cerebral cortex which leads to impaired speech, movement, sensation, perception and voluntary physical action.
But there are many more symptoms of dementia than just memory loss. For many people, early symptoms of dementia may have nothing to do with memory loss at all.
In addition to memory impairment, dementia symptoms include personality and mood changes, difficulty in finding the right words to use or understanding what people are saying, and difficulty performing routine tasks.
Frontotemporal dementia, for example, affects the frontal and temporal lobes of the brain. The frontal lobe controls executive function, or how we cognitively control our behavior. This includes cognitive processes that we take for granted each moment we are awake: thinking, planning, and problem-solving. Executive function is how we control our emotions and our behaviors and it forms the foundation of our individual personalities.
The temporal lobes of the brain — found only in primates — are responsible for processing sensory input, such as sights and sounds. When dementia impacts the left temporal lobe, people have difficulty understanding the meaning of words or remembering the names of objects. The right temporal lobe deals with processing visual sensory data. When impacted by dementia, this results in difficulty with recognizing faces and familiar objects.
Some types of dementia affect the motor or sensory cortices, thus impacting fine and gross motor control and sensations such as taste and smell. Other dementias affect the occipital lobe of the brain, making it difficult for people to make sense of visual information.
Dementia can also impact the parietal lobes of the brain. When dementia affects the left parietal lobe, people experience challenges with reading, writing, and processing numbers. The right parietal lobe, on the other hand, helps us process and orient ourselves within a 3D world. When dementia affects this part of the brain, people may have trouble seeing and recognizing three-dimensional objects which can impact wayfinding abilities.
Alzheimer’s typically affects older people, but people of any age — even as young as 18 — can develop other forms of dementia. Some progress very quickly, while others do not. While all forms of dementia are considered terminal, some can be effectively treated with non-pharmacological interventions. To date, over 400 types of dementia have been defined. Alzheimer’s is just one.
It’s more than memory loss. It’s more than old people. It’s more than Alzheimer’s.
Learn more at www.dementiaallianceinternational.org