Not all dementias are alike. The most common type of dementia is Alzheimer’s Disease. This was first described by a physician, Dr. Alois Alzheimer in 1906. He described some of the changes in the brain of a woman that examined after she died. Her brain had many abnormal clumps of amyloid (amyloid plaques) and tangled bundles of fibers (neurofibrillary tangles or tau).
Alzheimer’s disease is diagnosed most frequently by a neurologist, geriatrician, or primary care physician with experience in diseases of memory. While the diagnosis is often clear once the patient has advanced symptoms, it is sometimes hard to make the diagnosis early on.
Early on, when symptoms are unclear, the term “possible” or “probable” Alzheimer’s is frequently used. There are tests that have been used in clinical trials to ensure that the diagnosis is correct, however, these are not in common use in clinical settings for many reasons. The most common test remains a physician encounter, with a set of questions. The questions are typically asked in a set sequence and in a set way.
Mild Cognitive Impairment
Mild cognitive impairment or MCI, is a condition where the patient, and sometimes the clinician, can tell that there is some loss of memory function. However, unlike dementia, the person is able to function independently with no loss of other vital cognitive domains. If there is a loss in more than one cognitive domain, it is not sufficient to alter the person’s ability to remain independent. MCI is often found in Alzheimer’s patients.
An unclear question that remains with regards to mild cognitive impairment is whether this represents the early stages before the start of dementia, or whether this is simply a static condition. Early on, it may be impossible to tell these two conditions apart. However, guidelines suggest that a similar approach is taken with both MCI and dementia, which includes looking for causes of the changes in memory and treating similarly.
People who experience MCI should be followed by a clinician over time, to ensure that they remain as healthy and safe as possible.
Pseudodementia is a condition where the person appears to have dementia, but in fact has a different medical condition. Typically, this is due to depression. In older adults, depression must be considered when looking for possible causes of dementia, since the treatment is very different for depression than it would be for dementia.
There are simple, and well-validated, screening tools that can be used by providers to help evaluate people for possible underlying depression. This includes the Geriatric Depression Score, the PHQ-2, and the PHQ-9.
Dementia that is caused by stroke is also referred to as vascular dementia. Typically, this is caused by more than one stroke, with a cumulative loss of cognitive function over time.
Dementia with Lewy Bodies
Dementia with Lewy Bodies can be challenging to diagnose early but differs from Alzheimer’s disease. People with Dementia with Lewy Bodies, also known as DLB, typically experience symptoms like hallucinations and sleep disruption fairly early on in the disease. These people may also appear to have symptoms of Parkinson’s Disease, such as difficulty walking, stiffness and swings in their blood pressure when seated and standing.
Frontotemporal dementia, or FTD, is a type of dementia that is recognized due to an abnormality on a brain scan. Typically, in people with symptoms of FTD, there is a significant loss of brain tissue in the frontal lobes and in the temporal lobes of the brain. This can be found on one or both sides of the brain and may involve only the frontal lobes or only the temporal lobes. The medical term used to describe the loss of tissue seen on scans is atrophy.