Six common causes of forgetfulness

Patsy Westcott / 07 October 2015

Getting a bit absent-minded? Don’t worry, it doesn’t mean you’ve got dementia - here’s our guide to the top six reasons for becoming forgetful.



Trouble remembering phone numbers? Dither over simple decisions? Problems following recipes? You’re not alone – particularly if you’re over 50. And with the constant flow of stories about Alzheimer’s disease and dementia in the press and online, it’s not surprising that such mental slips raise the question, ‘Could it be dementia?’ 

Well, the good news is that such everyday trials are usually just part of the normal cognitive changes that affect us all as we age. 

Dementia is far more than ordinary forgetfulness or occasional foggy thinking, says Professor June Andrews, who is director of the Dementia Services Development Centre at the University of Stirling. ‘You need to start worrying only if you experience a significant, progressive downturn in your mental capacity,’ she says. ‘It’s normal to misremember phone numbers, for instance, but not to forget how to use your mobile or what it’s for.’

Even if you do experience more serious symptoms, don’t despair. Numerous other medical problems have symptoms that make people think they have dementia. The most common are outlined below.

1. Vitamin B12 deficiency

Dementia-like symptoms include: bad judgment and low mood.

Vitamin B12 plays a vital role in maintaining the brain and nervous system. It’s found in meat, poultry, eggs and milk. But age-related changes in stomach acid, certain medications (including proton pump inhibitors used to treat reflux, antibiotics, metformin used to treat Type-2 diabetes) and excess alcohol can all deplete the body’s stores. 

Left untreated, a vitamin B12 deficiency can lead to brain shrinkage and symptoms such as confusion, apathy, depression, poor memory and judgment. Other problems, though, can include numbness, pins and needles, disturbed vision and unsteadiness on your feet. 

Find out more about Vitamin B12

Next steps

You should first ask your doctor for a blood test. Taking a supplement could help. An Oxford University study found that taking a combination of vitamin B12 (0.5mg/day), plus folic acid (0.8mg/day) and vitamin B6 (20mg/day) for two years significantly slowed brain shrinkage in those with mild cognitive decline.

Find out more about vitamin B6

Learn more about folic acid

2. Depression

Dementia-like symptoms include: poor concentration and apathy. 

Depression may affect more than one in five people over 65, according to figures from Age UK – often without them realising it. (The figures also show women are more prone to depression than men.)

‘Many people wrongly think the overriding symptom is sadness,’ observes Dr James Warner, who is national professional adviser for old age psychiatry at independent health regulator the Care Quality Commission. ‘But memory problems, trouble concentrating, struggling to get things done and loss of interest in activities can be just as prominent.’ 

Depression is linked with cognitive problems in two out of five older people. ‘However, while someone who is depressed may meet an acquaintance and forget their name, they will know who they are,’ explains Dr Warner. ‘Someone with dementia, on the other hand, will be unable to identify the person behind the name.’ 

People with depression can also experience what doctors call ‘delayed verbal recall’, a problem remembering words, and may speak more slowly. ‘With dementia, though, this goes further,’ says Dr Warner. ‘Sufferers frequently forget words for common objects. For example, they may describe a cup as “that thing you put tea into”.’ 

Find out more about treatments for depression

Next steps

Again, you should see your GP – depression is, of course, a real illness that can be treated successfully. 

Antidepressants, exercise, reminiscence therapy and advice on stress-management are all options. And in a recent review in the International Journal of Geriatric Psychiatry, cognitive behavioural therapy was reported to help improve planning and problem-solving skills, as well as lifting mood, in older people with depression and cognition problems.

3. Urinary tract infection (UTI)

Dementia-like symptoms include: hallucinations and restlessness

For many, this common bacterial infection can bring on a fever, create an urgent need to pee or make it uncomfortable to do so. But older sufferers – whose immune systems may no longer respond to such infections, who may have less sensitive pain receptors and could already have problems going to the loo – may not notice anything unusual. 

Apart, that is, from delirium. Often a result of the dehydration a UTI causes, its effects include lack of awareness of surroundings, inability to follow a conversation or speak clearly, vivid, scary dreams, seeing people or things that aren’t there, restlessness, wandering, slowness and mood changes. 

‘But what distinguishes these problems from dementia,’ says Dr Trisha Macnair, specialty doctor in medicine for the elderly with Surrey Community Health, ‘is that they tend to come on quickly [hours, days or weeks], rather than developing over years.’

Other UTI symptoms to look out for include cloudy, unpleasant-smelling urine, a general feeling of being unwell or nausea. Our thirst-sensation is blunted with age, so guard against dehydration in general by drinking plenty of tea and water. 

Find out more about urinary tract infections

Next steps

A course of antibiotics, drinking lots of water, a healthy diet and rest usually bring fast relief. 

Cranberry tablets (which contain compounds thought to stop bacteria sticking to the urinary tract’s walls) or probiotics may help keep UTIs at bay if you’re prone to them.

Find out more about avoiding dehydration

Learn more about cranberry's health-boosting properties

4. Thyroid problem

Dementia-like symptoms include: failing memory and fatigue

‘The thyroid, a small butterfly-shaped gland in your neck, produces hormones that regulate most bodily functions, including mood and cognition. And, like dementia, symptoms of thyroid problems can creep up relatively slowly,’ points out Dr Warner, who is also consultant psychiatrist at the Central North West London Foundation Trust. 

An underactive thyroid is more common in women and is estimated to affect one in 20 people aged 60-plus. 

Difficulty thinking, poor working memory (the kind used to follow the steps in an instruction manual), slowed reactions and low mood are some clues. Other tell-tale signs that may distinguish it from dementia, however, include weight gain, over-sensitivity to cold, dry skin, hair loss and constipation.

An overactive thyroid can trigger poor attention, concentration and memory for words, anxiety, restlessness, palpitations, over-sensitivity to heat and weight loss. 

Next steps

A simple blood test can identify if your thyroid is pumping out too few or too many hormones. Medication usually sorts things out within weeks. Occasionally, other treatment, including surgery, may be needed for an overactive thyroid.

Always tired? Find out why

5. Parkinson's Disease

Dementia-like symptoms include: slow reactions and short attention span.

It’s not widely known, but mild cognitive impairment can be a sign of this nervous-system condition. 

‘Like dementia, Parkinson’s is a long time developing,’ explains Dr Warner. ‘What we call non-motor symptoms often present up to ten years before classic symptoms, such as a “masked” [unexpressive] face, tremor and difficulty moving.’ 

Problems with attention and concentration, for example, can make things such as reading a newspaper difficult, while slower thought processes can affect how long it takes you to make decisions or respond in a conversation. 

Next steps

Parkinson’s UK has a non-motor symptoms questionnaire that you can take to your GP to help them scrutinise your symptoms. Visit parkinsons.org.uk or call 0808 800 0303. 

Parkinson's disease: hope on the horizon

6. Medication overload

Dementia-like symptoms include: confusion.

Getting older invariably means taking an increasing number of medicines and, when they’re combined, they can cause cognitive symptoms that resemble long-term mental issues. 

Some drugs cause problems by themselves. ‘Anticholinergics – prescribed to treat asthma, incontinence, insomnia, gastrointestinal problems, muscle spasms and high blood pressure – may cause confusion by blocking acetylcholine, a brain messenger chemical involved in memory and learning,’ says Dr Warner. Feeling light-headed, having a dry mouth, constipation, bladder problems or blurred vision are other possible side effects.

‘Sleeping pills and “opiate” painkillers for conditions such as arthritis and back pain can also damage alertness,’ he adds.

Next steps

Always take medications exactly as prescribed. Gen up on side effects and possible cross-reactions by reading in-pack instructions for prescription and over-the-counter medications, including herbal and dietary supplements. 

If you’re uncertain, check with your GP or pharmacist. Make sure medications are reviewed regularly to check they are still appropriate for your needs.

A guide to understanding drug interactions


Professor June Andrews is the author of Dementia: The One-Stop Guide. Practical advice for families, professionals, and people living with dementia and Alzheimer’s disease. (Profile Books, £9.99)

The opinions expressed are those of the author and are not held by Saga unless specifically stated.

The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.