Causes of Dementia

Dementia is not one disease but the end result of several - a set of symptoms caused by damage to brain cells. Knowing the causes matters because a few of them are reversible, and several of the risks are modifiable.

The diseases that cause dementia

• Alzheimer's disease: the commonest cause (about 60-70%) - abnormal protein deposits gradually damage brain cells, starting in memory centres
• Vascular dementia: the second commonest - strokes and damaged small blood vessels starve brain regions; often steps down in noticeable dips
• Lewy body dementia: protein deposits causing fluctuating confusion, visual hallucinations and Parkinson-like stiffness
• Frontotemporal dementia: earlier onset (50s-60s), starting with personality and behaviour change rather than memory
• Mixed dementia: two or more causes together - very common in the oldest patients

The reversible mimics (why assessment matters)

Some conditions imitate dementia and can be FIXED - this is why every new "dementia" deserves a proper medical workup:

• Vitamin B12 deficiency - common in vegetarians, treatable
• Thyroid underactivity - a blood test away
• Depression in the elderly - can look exactly like dementia
• Normal pressure hydrocephalus - fluid on the brain, sometimes surgically treatable
• Medication side effects, chronic alcohol use, infections

The risk factors that stack the odds

• Age: the biggest - risk doubles roughly every 5 years after 65
• Family history and certain genes
• The heart-brain axis: high blood pressure, diabetes, high cholesterol, smoking, obesity - what hurts the heart ages the brain
• Hearing loss, social isolation, low education and mental inactivity - surprisingly strong contributors
• Head injuries, poor sleep, heavy alcohol

One-line summary

Dementia is brain-cell damage from diseases like Alzheimer's and vascular disease - but before accepting the label, rule out the reversible mimics (B12, thyroid, depression), and know that blood pressure, diabetes, smoking and loneliness are risks you can actually act on.