What is dementia? Is it a disease, a term synonymous with Alzheimer's disease or an umbrella term for a group of symptoms involving cognitive deterioration?
All of these answers are right. It is a general term, and it is an umbrella term for a range of conditions that affect the brain. It is a group of symptoms affecting the ability to process thought. It affects memory, as well as thinking, behavior and social activities - severely enough to interfere with daily living and independent living.
Some characteristics of dementia are that it is progressive, it is gradual in onset and often overlooked. Communication is impaired. People with dementia have difficulty performing activities of daily living. There is memory loss, impaired reasoning, and a decline in the ability to learn new information. Physicians say that when it is serious enough to affect at least two cognitive functions such as memory, attention, thinking, or language, that is when dementia has started showing its face.
The decline and the trajectory of dementia is interesting. It is not a normal part of aging. With normal aging, there is a slight decline in cognition. Then as some people age, they develop mild cognitive impairment (MCI). A significant percentage of people with mild cognitive impairment progress on to dementia, and become unable to function independently and perform activities of daily living. It is the decline in function that distinguishes between MCI and dementia - the inability to take care of oneself and to function independently.
Dementia is multi-factorial. It affects all regions of the brain and connections between the different regions of the brain. For example, the parietal lobe is affected, and so we can see the communication difficulty; impairment in the frontal lobe leads to problems in judgment and execution of basic tasks; impairment in the temporal lobe interferes with language, hearing, and recognition; and the effect on the hippocampus interferes with new memory.
Alzheimer’s is the major cause of dementia, accounting for about 60% to 80% of dementia cases. But, because it is a highly variable condition, it is under-detected in primary care. It is typically only detected at the later stages. The Gerontological Society and the Alzheimer's Society have developed a toolkit for helping primary care doctors recognize and identify dementia earlier.
There are individual differences in the amount of pathology required for the initial expression of clinical symptoms. It is very important to understand that there are significant differences between individuals with regard to when the pathology expresses itself. Some people with neuropathological brain changes do not have dementia. Individuals who have good cognitive reserves can tolerate more neuropathology before they develop dementia. This is significant, and this is why it is very important to encourage patients to remain engaged; engagement is protective against a decline in cognition. Less cognitive reserve leads to earlier development of dementia. The reserve that people demonstrate may be related to the anatomical substrate of the brain, to cognitive adaptation, or to resilience. There are a number of variables that influence this.
Engagement in leisure activities really makes a difference in terms of the onset of cognitive decline. If individuals participate in six or fewer leisure activities they are at greater risk for developing dementia, as compared to individuals who engage in more than six leisure activities. Engagement is very important because it contributes to cognitive activity, which strengthens the functioning and plasticity of neural circuits.
Please refer to the SpeechPathology.com course, A Dementia Primer for Speech-Language Pathologists, for more information on dementia, its connections to hearing loss, and therapeutic modifications SLPs can employ to optimize audibility and communication.