Dementia is not a single disease, but a group of clinical syndromes caused by brain pathology. Its core features are the gradual decline of memory, language, comprehension, judgment, behaviour, and daily living abilities, accompanied by changes in personality and emotions. With population ageing, dementia has become an important global public health issue.
I. Alzheimer’s Disease
Alzheimer’s disease is the most common type of dementia, accounting for 60–80% of all cases. Its pathological basis is the deposition of abnormal proteins in the brain, including β-amyloid plaques and tau protein tangles, leading to progressive neuronal death. In the early stage, patients often present with recent memory decline, such as forgetting events that just happened or repeatedly asking the same questions. As the disease progresses, language ability, sense of direction, comprehension, and executive function are gradually impaired, eventually affecting daily self-care ability.
The course of Alzheimer’s disease usually lasts 10–20 years and is progressive in nature. Clinically, early recognition and diagnosis are crucial, because although current drug and non-drug treatments cannot cure the disease, they can slow its progression, improve quality of life, and reduce family caregiving burden.
II. Vascular Dementia
Vascular dementia is the second most common type, accounting for about 10–20%. Its cause is closely related to cerebrovascular disease, such as stroke or chronic cerebral hypoperfusion. The condition often shows a “stepwise” deterioration: after each stroke, the patient’s cognitive function declines significantly, then stabilises for a period, before further deterioration due to another vascular event.
Clinically, patients with vascular dementia often have cardiovascular risk factors such as hypertension, diabetes, and hyperlipidaemia. Prevention and control of these risk factors are the core of treatment. Unlike Alzheimer’s disease, the course of vascular dementia is less regular, and symptoms may suddenly worsen due to vascular events.
III. Lewy Body Dementia
The pathological feature of Lewy body dementia is the presence of abnormal protein “Lewy bodies” within brain cells. Patients of this type show great fluctuation in symptoms, with cognitive function varying significantly even within the same day. Common symptoms include visual hallucinations, confusion, unstable attention, and Parkinsonian motor symptoms such as rigidity and bradykinesia. In addition, patients often have rapid eye movement (REM) sleep disorder, and may act out their dreams at night.
The clinical challenge of Lewy body dementia lies in its overlapping symptoms with Alzheimer’s disease and Parkinson’s disease, which makes misdiagnosis easy. Correct identification helps in choosing appropriate medications and avoiding drugs that may worsen symptoms (such as certain antipsychotics).
IV. Frontotemporal Dementia
Frontotemporal dementia mainly affects the frontal and temporal lobes of the brain, which are responsible for personality, behaviour, and language. Patients usually develop the disease between the ages of 40 and 60, younger than other types. Early symptoms are not memory decline, but changes in personality and behaviour, such as impulsivity, lack of empathy, socially inappropriate behaviour, or language disorders such as aphasia. Memory decline often appears only in the later stages of the disease.
This type is partly related to family heredity, so clinicians need to pay special attention to family history. Because patients are relatively young, the impact on families and society is particularly profound, and caregivers often face heavy pressure.
V. Mixed Dementia
Mixed dementia refers to the coexistence of two or more pathologies, the most common combination being Alzheimer’s disease with vascular dementia. Patients of this type present with more complex clinical features, showing both progressive decline and sudden deterioration due to vascular events. With increasing age, the proportion of mixed dementia also rises.
VI. Other Secondary or Reversible Causes
In addition to the major degenerative dementias mentioned above, there are also some secondary or reversible causes, such as brain trauma, brain tumours, hydrocephalus, infections, vitamin deficiencies, hormonal disorders, drug toxicity, or alcoholism. If these conditions are diagnosed and treated early, some patients’ cognitive function may improve. Therefore, clinicians must conduct comprehensive investigations to avoid missing reversible causes.
Diagnosis and Management
The diagnosis of dementia is not based solely on clinical observation, but requires a combination of multiple assessments, including medical history, neuropsychological testing, imaging studies, and blood tests. Early diagnosis helps to:
- Slow disease progression: through drug and non-drug treatments, improving patients’ quality of life.
- Reduce family burden: by arranging caregiving resources early, preventing caregiver overload.
- Promote community inclusion: by enhancing public understanding of dementia and reducing stigma.
In terms of management, in addition to drug treatment, non-drug interventions are also very important, including cognitive training, physiotherapy, occupational therapy, psychological support, and community resource linkage. Caregiver education and support are equally indispensable.
Conclusion
Dementia is a diverse group of diseases, including Alzheimer’s disease, vascular dementia, Lewy body dementia, frontotemporal dementia, mixed dementia, and other secondary or reversible causes. Each type has different clinical features, disease course, and management strategies. Not all dementias are irreversible; early diagnosis and intervention are crucial.
In an ageing society, the challenge of dementia is becoming increasingly severe. Only through professional diagnosis, interdisciplinary collaboration, and community education can we truly improve the quality of life of patients and families, and promote social understanding and acceptance of dementia.
