It appears that many people think Alzheimer's disease and dementia are the same; this is incorrect. So what exactly is the difference?

By Chloë Verhagen - Neuropsychologist / PhD Candidate Neurology

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Plenty of people seem to be confused by the terms Alzheimer's disease and dementia, using them interchangeably. However, Alzheimer's disease and dementia are not the same. Additionally, memory problems are not exclusively present in Alzheimer's disease.

What is dementia?

Dementia is an umbrella term for a neurodegenerative condition, with cognitive problems (problems related to thinking) that usually start off mild but decline further over time. To get diagnosed with dementia, at least two cognitive domains (for example memory and language) should be impaired to such an extent that they interfere with daily life activities. To be considered 'impaired,' someone’s cognitive performance is substantially lower than what you would expect based on their age, educational level, and former level of functioning. Dementia can be caused by different types of diseases that affect the brain. Consequently, there are different types of dementia.

What is Alzheimer's disease?

Alzheimer's dementia is a type of dementia and is the result of the pathology of Alzheimer's disease (AD) in the brain. It has its own unique clinical profile when it comes to biomarkers, cognitive impairment, and disease progression. AD is famous for its so-called amyloid plaques and tangles of tau in the brain. These are biomarkers that indicators of the presence of pathology of AD and can be found in the cerebral spinal fluid, or visualized with a tracer on a Positron Emission Tomography (PET). In a later stage, tissue loss, or 'atrophy' can be visualized on Magnetic Resonance Imaging (MRI). Its severity can be estimated in-vivo with validated atrophy scales. However, the presence of biomarkers and some brain tissue loss does not show a causal relationship with the severity of someone's cognitive problems and functioning in daily life. Some people can function normally while having severely affected brains, while others are already impaired before tissue loss is even visible. Biomarkers thus indicate the presence of pathology of AD in the brain, but are not always able to tell us something about the presence of clinical symptoms. Because of this reason, the clinical probability diagnosis of AD is often mainly based on the presence of clinical symptoms and their progression (such as gradually increasing memory problems, which is by the way often, but not solely, seen in Alzheimer's disease) and not on the presence of pathology of AD in the brain.

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However, this is currently under discussion, since there are also patients that have AD pathology in the brain, but are not showing any clinical symptoms. As mentioned, the presence of pathology does not guarantee that symptoms will develop later on. Should these people be informed about the pathology? Since there is no cure for AD yet, you can imagine this is giving rise to some firey discussions in the field.

Several types of dementia

So now you know: Alzheimer's disease is a type of dementia, and despite the fact that this is the leading cause of dementia worldwide, the word type of dementia already suggests that there are more than one. You may have heard of frontotemporal dementia, Lewy-body dementia, vascular dementia Parkinson's dementia to mention a few. Each of these types show a lot of clinical overlap, but also have their own typical characteristics and disease progression. To give you an idea, frontotemporal dementia, for instance, is known for its impulse problems, personality changes, repetitive behavior or sometimes degradation of verbal understanding. Fluctuating cognitive problems, sometimes in combination with hallucinations, are seen in Lewy body dementia. Vascular dementia usually has a more gradual course, often with stepwise decline. It slows down someone's cognitive processing speed and can result in all kinds of cognitive problems depending on the location of vascular damage in the brain. Parkinson's dementia is a result of advanced Parkinson's disease and leads to slower processing of information and consequently complicates understanding. There are more types than listed above and to make matters even more complicated, mixed pathologies are rather the rule than the exception.

Memory problems ≠ Alzheimer's disease

The presence of memory problems can not solely be attributed to Alzheimer's dementia. It might surprise you, but every type mentioned above- early in the disease or at a later stage- can result in the co-occurrence of memory problems. As you can imagine, this can severely ambiguate the diagnosis of different dementia types. For instance, the primary issue with the forgetful partner we mentioned in the introduction might not be memory problems. It is possible that she slowed down in her processing speed, resulting in that information streams of daily life just go too fast for her to imprint. In this case, memory problems are an indirect result of other cognitive problems, and not a result of a degenerated “memory center”. It could just as easily have been caused by other pathologies than frank AD.

Does it matter where memory problems originate from? Yes, it does, because when memory problems arise from a different pathology and work through a different mechanism, other treatment options, psychoeducation, and daily life advice for caregivers are needed. Incorrect communications on this might impact the quality of life of our patients. To give an example: a piece of simple environment-oriented advice such as: 'talk slower and use smaller chunks of information, might work perfectly for the forgetful partner that claims that 'the world goes faster than it used to,' but not for the person that cannot store any new information at all.

Another clinical phenotype that is expressed through memory problems or 'forgetfulness', is a clinical depression. Depression mimics the clinical presentation seen in the early stages of dementia; however, the expression of memory problems in depression is also the result of different mechanisms than those of AD (the problems can for example be a result of reduced executive functioning or impaired processing speed). Depression on its own will never reach the level of cognitive impairment that is seen in dementia.

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What can be done to reduce uncertainty regarding the diagnosis of loved ones?

As you can see, diagnosing (early stages of) AD or another form of dementia is not that easy. Luckily, nowadays, there is a lot of research going on, and diagnosis is usually not merely based on reported cognitive complaints and their progression anymore. Clinicians make use of biomarkers, imaging of the brain, and extensive neuropsychological testing if needed. There are also some things you can do yourself to disambiguate the diagnosis of your loved ones. First, it is very helpful for the clinicians if you write down specific examples of situations in which cognitive problems arise. This can help to unravel different underlying mechanisms. For example: don’t tell that your partner forgets everything, but be more specific:

‘My partner has trouble with recalling the names of friends. However, when I mention the names, she clearly recognizes them’.

Secondly, make sure that, when you receive a diagnosis, your clinician not only informs you about the disease and its progression but also on how to handle specific cognitive problems in daily life. Some daily problems can be circumvented or reduced.

Often specialized clinicians, such as neurologists or geriatricians, will redirect the patient to a (neuro)psychologist for an additional 'neuropsychological assessment'. Based on this assessment (consisting out of tasks to measure cognitive functions such as memory, concentration, psychomotoric speed, executive function, language, orientation, etc.) a neuropsychologist can draw-up a patients cognitive profile, judge the probability of a particular disease (e.g., early-stage Alzheimer's vs depression) and more importantly, offer simple compensatory techniques that the patients and their direct environment can apply to daily life.

As you can imagine, getting diagnosed with dementia and all the cognitive changes that patients are going through can be quite impactful to their psychological well-being as well. Especially early in the disease when cognitive complaints are still relatively mild and a patient is still able to comprehend what is happening, we see this can be hard. It is therefore very reasonable to see a psychologist somewhere in the process to talk about these changes and get some support. Let also not forget about partners and children here, who are going through a period of loss and adaptation as well. Please do not hesitate to see a therapist when you feel you can also use some support.

Everything mentioned above will help the patient and their environment to better understand what is happening, what to expect and how to explain to others what they are going through. Understanding and acting upon this understanding might alleviate suffering and can make it possible for patients to enjoy life more despite their condition. We must bear in mind that we, as the direct environment of the patient, play an essential role in that regard, and are able to make a difference.

All things considered, is quality of life not most important of all?

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