Dementia is a syndrome characterized by deterioration in cognition, resulting in impairment in the activities of daily living. Cognitive decline often affects multiple domains.
The incidence of dementia doubles with every 6.3 year increase in age, from 3.9 per 1000 person-years at age 60-64, to 104.8 per 1000 person-years at age 90 and over.
The global number of individuals who lived with dementia increased from 20.2 million in 1990, to 43.8 million in 2016, and dementia was the fifth leading cause of death globally, accounting for 2.4 million deaths. It is thought that the number of people living with dementia will almost double every 20 years, reaching 75 million in 2030 and 131.5 million in 2050, with this increase predominantly affecting developing countries.
The majority of cases of dementia have degenerative and vascular causes. Other causes include infections, inflammatory diseases, neoplasm, toxic insults, metabolic disorders, and trauma.
An estimated 11% to 14% of dementias are caused by potentially reversible conditions; therefore, ruling out these conditions is of the utmost importance when considering a diagnosis of dementia.
A number of conditions can present in a similar way to dementia syndrome and need to be considered during the evaluation. These include delirium, depression, amnestic syndromes, aphasia, and normal aging.
- Amnestic syndromes
- Frontotemporal dementia
- Parkinson disease
- Huntington disease
- Brain tumors
- Cushing syndrome
- Primary hyperparathyroidism
- Acute intermittent porphyria
- Primary hypothyroidism
- Wilson disease
- Vitamin B12 deficiency
- Traumatic brain injury
- Lyme disease
- Syphilis (late)
- Systemic lupus erythematosus
- Sjogren syndrome
- Medication use
- Normal pressure hydrocephalus
- Creutzfeldt-Jakob disease
Associate Professor of Clinical Psychiatry
AG declares that she has no competing interests.
Dr Aarti Gupta would like to gratefully acknowledge Dr Rajesh Tampi, Dr Sarper Taskiran, Dr Javier Lopez, and Dr Sunanda Muralee, the previous contributors to this topic. RT, ST, JL, and SM declare that they have no competing interests.
Associate Professor of Psychiatry
Yale School of Medicine
KW declares that she has no competing interests.
Memory Disorders Program
Department of Neurology
University of North Carolina at Chapel Hill
DK has received research support, speaking honoraria, and consulting fees from Eisai, Forest Laboratories, Johnson & Johnson, Medivation, Novartis, Ortho-McNeil, and Pfizer.
Professor Emeritus of Mental Health
University of Aberdeen Institute of Applied Health Sciences
LW declares that he has no competing interests.
Cleveland Clinic Lou Ruvo Center for Brain Health
RS declares that he has no competing interests.
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