Differences Between Dementia and Alzheimer’s Disease and Parkinson’s Disease

Since the word ‘dementia’ is used a lot, many people think that it is the name of a disease in itself. There is also a misconception that ‘Alzheimer’s disease’ or ‘Parkinson’s disease’ are different terms for ‘dementia’. However, dementia, Alzheimer’s disease, and Parkinson’s disease are completely different concepts.

‘Dementia’ is a term that encompasses symptoms that deteriorate daily functions.

Humans live by performing social roles based on cognitive functions. Dementia is the loss of cognitive function and the ability to engage in social activities. Dementia itself is not a diagnosis of a disease like ‘asthma’ or ‘bronchitis’. Dementia refers to a ‘symptom complex’ that causes difficulties in daily life as a result of complex symptoms such as memory impairment, behavioral disturbance, cognitive dysfunction (related to thinking, reasoning, language, etc.), personality change, and personality disorder.

‘Alzheimer’s disease’ and ‘Parkinson’s disease’, which are often confused with dementia, are actually ‘causal diseases’ that can cause symptoms of dementia. Simply put, patients with memory impairment, behavioral impairment, or cognitive impairment may have Alzheimer’s or Parkinson’s disease, a neurodegenerative disease. Dementia caused by Alzheimer’s disease accounts for about 50-60% of all dementias. It is known that 30-40% of patients with Parkinson’s disease show symptoms of dementia at the end of the disease.

There are various causes of dementia, such as Alzheimer’s disease, Parkinson’s disease, and decreased cerebral blood flow.

Dementia occurs for a variety of reasons, and the symptoms of dementia may vary slightly depending on the cause.​

In Alzheimer’s disease, neurons in areas of the brain that are important for maintaining intellectual abilities are lost or the amount of neurotransmitters that travel between neurons decreases. It starts with forgetfulness, and as the disease progresses, impairments in speech, comprehension, reading and writing skills occur.

Parkinson’s disease is a disease in which dopaminergic neurons in the substantia nigra are destroyed. Dopamine, a neurotransmitter, is involved in the precise movement of our body. As a result, Parkinson’s patients stiffen their body and limbs, making their movements dull, and their hands tremble when they are still. The patient may also have slurred speech or shortened stride length.

There are many causes of dementia besides Alzheimer’s and Parkinson’s. Vascular dementia is caused by narrowing or blockage of blood vessels in the brain, reducing the amount of blood flowing into the brain. In addition, degenerative brain diseases such as ‘Huntington’s disease’, in which nerve cells in a specific part of the brain are selectively destroyed, and ‘Creutzfeldt-Jakob disease’, in which the brain is perforated, can also lead to dementia.