Dementia & Memory Disorders

Dementia is a decline in memory and thinking that is severe enough to interfere with everyday life and is caused by disease of the brain. Ageing on its own does not cause it. Forgetting a name and retrieving it an hour later is ordinary; losing the thread of how to do something you have done for forty years is not.

It is a description and not one disease. Alzheimer's disease is the commonest cause. Damage to the small blood vessels of the brain is the next, and it often follows years of raised blood pressure, diabetes or smoking, and tends to progress in steps instead of smoothly. Dementia with Lewy bodies brings fluctuating alertness, vivid visual hallucinations and stiffness of movement. Frontotemporal dementia appears younger and changes personality, judgement or language before it touches memory. In older people two causes together are common.

Several conditions imitate dementia and can be reversed: depression, an underactive thyroid, vitamin B12 deficiency, the accumulated effect of certain medicines, alcohol, untreated sleep apnoea, and a slow collection of blood or fluid around or within the brain. Some of those have specific treatments that recover most of what was lost. Finding them is the first job of an assessment, and it is the strongest reason to come early instead of waiting another year.

Most of the diagnosis is the history, and it needs two halves. Yours, and that of someone who sees you every day. Bring a family member to the appointment, because the account of what has changed, when it started, and whether it slid gradually or dropped in steps is information the person affected genuinely cannot supply.

In clinic your memory, attention, language, planning and orientation are tested with structured questions and simple drawing and recall tasks. The score matters less than the profile it produces and the fact that it can be repeated in a year and compared. Your doctor then examines you properly: the way you walk, tremor and stiffness, eye movements, and, crucially, vision and hearing, since uncorrected hearing loss makes thinking look far worse than it is and is one of the most rewarding things to fix. Mood is asked about directly, because depression in an older person can look identical to dementia and is treatable.

Blood tests look for the reversible causes. A scan of the brain is usually done once, to see the pattern of change and to exclude a collection of blood or fluid that would be treated in its own right. The diagnosis itself is made clinically, by putting all of that together, and it is often reviewed and refined at the next visit.

Where a reversible cause is found and corrected, thinking improves over weeks to months, and how much returns depends largely on how long it was left. That is the best outcome available and it is the reason for a full assessment.

Where the cause is a degenerative disease, the unit is years and the aim is function and independence for as long as possible. Medicines used for some causes are reviewed at about three months; their effect is real and modest, and they are continued while they help. What tends to matter more across a year is everything around them: treating hearing loss, correcting vision, physical activity most days, sleep, staying socially engaged, reviewing medicines that cloud thinking, and controlling blood pressure, blood sugar and cholesterol, which slows the vascular contribution in almost everybody.

The practical arrangements do more good than any prescription. A predictable daily routine, the day written down where it can be seen, labels, a safe kitchen, a plan for driving, and blister-packed medicines all extend independence. So does support for whoever is doing the caring, since carer exhaustion is the commonest reason that care at home stops working. Put the legal and financial arrangements in place early, while the person can take part in making them.