Memory loss and forgetfulness: causes, red flags and assessment

Misplacing keys, forgetting why you walked into a room or struggling to recall a name until later are part of ordinary life, and become more frequent when you are tired, stressed or distracted. A memory problem is different in degree and effect: the same things happen repeatedly, you forget recent conversations or events altogether, and everyday tasks that used to be routine become difficult.

The NHS draws the practical line at impact. It says to see a GP if memory problems are affecting your day-to-day life, adding that it is often nothing serious but best checked because any treatment may work better if started early. It also asks relatives who are worried about an older person becoming increasingly forgetful to speak to a GP about whether it could be a sign of dementia.

The NHS memory loss page says memory loss can just be a natural part of getting older, and sometimes it may be caused by something common and treatable such as stress, anxiety or depression, or sleeping problems. Its dementia diagnosis page adds that memory problems do not necessarily mean dementia and may have other causes, including depression and anxiety, sudden confusion (delirium) caused by a medical condition such as an infection, an underactive thyroid and the side effects of some medicines.

Vitamin deficiency is another cause worth excluding. The NHS says vitamin B12 or folate deficiency can cause problems with memory, understanding and judgement, along with extreme tiredness, pins and needles, a sore red tongue and psychological problems ranging from mild depression to confusion, and that although many symptoms improve with treatment, some problems can be irreversible, so early diagnosis matters. Menopause can also bring poor memory and brain fog, which the NHS says may feel worse if sleep is poor.

• Low mood, anxiety, stress and burnout, which divert attention and make new information hard to hold.

• Poor sleep, including insomnia and sleep apnoea.

• Underactive thyroid, B12 or folate deficiency, and other metabolic problems found on blood tests.

• Medicines, such as some sedatives, painkillers and anticholinergic drugs; the NHS lists medicine side effects among other causes of memory problems.

• Alcohol and recreational drugs.

• Infections and delirium, particularly in older adults.

• Perimenopause and menopause.

The NHS explains that dementia is not a disease itself but a collection of symptoms resulting from damage to the brain by different diseases, such as Alzheimer's. The common early symptoms it lists are memory loss, difficulty concentrating, finding it hard to carry out familiar daily tasks such as getting confused over the correct change when shopping, struggling to follow a conversation or find the right word, being confused about time and place, and mood changes.

It says these symptoms are often mild, may get worse only gradually, and are sometimes termed mild cognitive impairment when not severe enough for a diagnosis of dementia. Some people with mild cognitive impairment stay the same, and some go on to develop dementia. You might not notice the symptoms yourself, and family and friends may not take them seriously for some time.

• Sudden new confusion, drowsiness or a marked change in alertness over hours or days: this may be delirium caused by an infection or another medical illness and needs prompt assessment.

• Call 999 for sudden weakness or numbness on one side of the body or face, difficulty speaking, or loss of vision; the NHS says stroke-like symptoms in vascular dementia, including muscle weakness or temporary paralysis on one side of the body, require urgent medical attention.

• Memory loss after a head injury, or with a severe sudden headache, seizure or loss of consciousness needs emergency care.

• Rapid decline over weeks, new hallucinations, marked personality change or getting lost in familiar places need an early GP review rather than waiting.

• Safety concerns, such as leaving the gas on, getting lost while driving or wandering, are reasons to ask for help quickly; the NHS notes that dementia may affect driving.

• Feeling hopeless or having thoughts of self-harm alongside memory problems needs immediate support through your GP, NHS 111 or, in an emergency, 999.

According to the NHS, a GP will ask about your symptoms and other aspects of your health, including whether you find it hard to manage everyday activities such as washing and dressing, cooking and shopping, and paying bills. To rule out other causes, the GP will do a physical examination and may organise tests such as a blood test and urine test. You will be asked to do a memory or cognitive test to check problems with memory or ability to think clearly.

If other causes are excluded, the GP may refer you to a specialist such as an old-age psychiatrist, a geriatrician or a neurologist, possibly in a memory clinic. The specialist may organise a brain scan such as CT or MRI and more detailed memory tests, and the NHS says most cases of dementia can be diagnosed after these assessments. The NHS notes that dementia can be difficult to diagnose, especially if symptoms are mild.

Keeping a short diary of examples (what was forgotten, when, and what the consequences were) gives the GP better information than a general impression. Bring a list of medicines and supplements, and ask a relative or friend to come with you. Treat poor sleep, low mood and anxiety, which respond to treatment and often lift memory performance too.

The NHS says an accurate and early diagnosis has many benefits, giving you and your family the best chance to prepare for the future, and that with treatment and support many people are able to lead active, fulfilling lives with dementia. It quotes an Alzheimer's Society study showing that 1 in 4 people wait for 2 years before getting help for dementia symptoms. Some people choose a private memory assessment for faster access to specialist testing and scans, which can sit alongside NHS follow-up.