Dementia is a general term for a large class of disorders characterized by the progressive deterioration of thinking ability and memory as the brain becomes damaged. Essentially, when memory loss is so severe that it interferes with normal daily functioning, it is called dementia. Less severe memory loss is usually referred to as mild cognitive impairment.

Did You Know?
Dementia is such an all-enveloping label that its symptoms can include some or all of the following:

personality change, depression, hallucinations, memory loss, paranoia, misidentifications, mania, aggression, agitation, irritability, wandering, incontinence, overeating, changes in walking patterns, sudden laughing or crying, screaming and many others.

It is sometimes estimated that dementia doubles in frequency about every 5 years from the age of 65, which suggests that around 5% of those age 65 have dementia and over 50% for those in the 85 to 90-year range.

Dementia is usually characterized by severe memory loss in conjunction with one or more of aphasia (loss of the ability to produce or understand language), apraxia (the inability to make certain movements, despite a healthy body), agnosia (problems recognizing familiar persons and objects, even though the senses are functioning) or executive dysfunction (inability to plan, organize or reason). Sufferers exhibit serious loss of cognitive ability, beyond what might be expected from normal ageing, and particularly in the areas of memory, attention, language and problem-solving.

The best known and most common type of dementia is Alzheimer’s disease , which accounts for 50-75% of all dementias. The second most common type, accounting for up to 20% of dementia cases, is vascular dementia, which has symptoms similar to Alzheimer’s but usually results from damage done to the brain by a blood clot or a haemorrhage cutting off the brain’s blood supply due to a stroke or succession of strokes. Other types of dementia include Lewy body dementia, frontotemporal dementia,Huntington’s disease and Creutzfeldt-Jakob disease. Some types of dementia are reversible (such as those caused by thyroid disease), while some (such as Alzheimer’s disease) are irreversible.

Dementia may be caused by specific events such as traumatic brain injury (also see post-traumatic amnesia) or stroke, or it may develop gradually as a result of neurodegenerative disease affecting the neurons of the brain (thereby causing gradual but irreversible loss of function of these cells) or as a secondary symptom of other disorders like Parkinson’s disease. It is also becoming apparent that some drugs used to treat other age-related diseases and conditions may have a deleterious effect on memory and hasten the onset of dementia, among them: anti-anxiety drugs (e.g. benzodiazepines); cholesterol-lowering drugs (e.g. statins); anti-depressant drugs (e.g. tricyclics); anti-seizure and anticonvulsant drugs; narcotic painkillers and opioids; Parkinson’s drugs (e.g. dopamine agonists); hypertension drugs (e.g. beta-blockers); sleeping aids (e.g. non-benzodiazepine sedatives); incontinence drugs (e.g. anticholinergics); first-generation antihistamines; etc.