The hidden causes of midlife brain fog – and why menopause isn’t always to blame

If you’ve been feeling more forgetful, unfocused or mentally foggy since entering midlife, you might be quick to assume that menopause is the culprit. But according to experts, there are an abundance of possible causes that could be lurking behind the brain fog.

‘Brain fog isn’t a medical diagnosis, but it’s a very real collection of symptoms that many women especially describe to me in clinic,’ explains Dr Punam Krishan, an NHS GP working alongside stairlift and home lift brand Stannah. ‘It’s that frustrating feeling of not being quite as mentally sharp as you used to be. You might struggle to find the right word, forget why you walked into a room, lose your train of thought halfway through a sentence, or find it much harder to concentrate than you once did.’

‘Brain fog is usually a symptom that something else needs attention, rather than a condition in its own right,’ she continues. ‘Our brains work best when they’re well rested, well-nourished and not constantly under pressure. Hormones, sleep, stress, physical health and emotional wellbeing all interact with the brain’s networks responsible for memory, attention and decision-making. When one or more of those systems is under strain, cognitive performance suffers.’

Why is brain fog so common in midlife women?

For many women, brain fog begins or worsens during midlife. But while hormonal changes during perimenopause can play a significant role, Dr Punam explains that they are rarely the whole story.

‘The reason I see it so often in women during midlife is that this stage tends to bring together several factors that all affect how the brain functions,’ she tells us. ‘Many women are also juggling careers, family and caring pressures. The invisible mental load of keeping everyone else’s lives running can take its toll. This is familiar for the ‘sandwich generation’ – those with teenage children and elderly parents.’

‘They don’t just have their own health to think about,’ Dr Punam continues. ‘If anything, they prioritise their relatives’ safety, wellbeing and independence over their own. This makes poor sleep, chronic stress and the normal changes that come with ageing harder to manage. So, it’s unsurprising so many women feel like their brain isn’t working the way it used to.’

Common causes of midlife brain fog

Perimenopause

While midlife brain fog is often caused by a multitude of competing factors, the hormonal changes of perimenopause can be one of the biggest contributing factors. ‘Oestrogen does much more than regulate periods; it also supports areas of the brain involved in memory, attention and processing information,’ Dr Punam explains.

‘As hormone levels fluctuate, many women notice that they become more forgetful or struggle to concentrate,’ she adds. ‘The good news however is that for many, these symptoms improve once hormones settle.’

Stress, work and caring responsibilities

Alongside hormonal shifts, several other factors can have a huge impact on how well your brain functions – particularly for women who are busy balancing careers with caring for elderly parents and teenage kids.

‘As the sandwich generation, you’re likely to be constantly thinking about work deadlines, school emails, when mum needs her medication, food shopping, birthdays and everyone’s appointments,’ says Dr Punam. ‘Your brain is carrying an enormous cognitive load. Stress hormones such as cortisol can affect attention, memory and decision-making. This can make you feel scattered even though you’re managing a huge amount.’

Anxiety and depression

When stress becomes chronic, or anxiety begins to develop, this can further worsen brain fog symptoms. ‘Anxiety doesn’t just affect how you feel emotionally – it also changes how your brain processes information. If your brain is constantly scanning for problems or worrying about the future, it leaves less capacity for concentration and memory.’

‘You might lie awake thinking “what if dad has another fall?”, “should I be worried about my husband’s memory?” or “how will my daughter cope if she fails her exam?” – so much of which is out of your hands, but occupies space in your mind.’

‘Depression can have a similar effect,’ she adds, ‘with many people describing feeling mentally slowed down.’

Poor sleep

Poor sleep is another common cause of brain fog – and getting good quality sleep can be much more difficult when you’re juggling stress, responsibilities and menopause symptoms.

‘The brain relies on good quality sleep to process information and store memories,’ Dr Punam explains. ‘If you’re waking several times a night because of hot flushes, anxiety, children or caring responsibilities, it’s much harder for your brain to perform at its best the following day.’

Underactive thyroid

Brain fog is not always caused by mental or emotional strain. For some, there might be an underlying physical cause. ‘An underactive thyroid is a common medical cause of brain fog, particularly in women,’ Dr Punam explains. ‘Alongside forgetfulness, you may notice fatigue, weight changes, dry skin or feeling unusually cold. It’s one of the reasons persistent brain fog shouldn’t simply be dismissed as stress.’

Nutrient deficiencies

Another common physical cause of brain fog is being deficient in certain vitamins or minerals. ‘Low iron, vitamin B12 deficiency and sometimes low vitamin D can all contribute to fatigue and reduced concentration,’ Dr Punam explains. ‘These are relatively simple things to check with your GP if your symptoms are persistent.’

ADHD

Brain fog is also a common symptom in people with ADHD – something that’s increasingly being diagnosed in midlife women. ‘We’re becoming increasingly aware that many women reach their forties or fifties before realising they’ve lived with ADHD all along,’ says Dr Punam. ‘Hormonal changes during perimenopause can reduce some of the coping strategies they’ve relied on for years. This can make difficulties with attention and organisation much more noticeable.’

Medications

If you’ve started any new medications recently, it’s worth checking the possible side effects, as Dr Punam says certain medications can cause you to feel more tired or foggy.

‘Some medicines can contribute to brain fog, including some antihistamines, pain medications and drugs that cause drowsiness,’ she explains. ‘It’s always worth reviewing whether symptoms started after beginning a new medication.’

Underlying health conditions

There are several chronic health conditions that can cause brain fog, so it’s important to check in with your doctor to rule these out. ‘Conditions such as long COVID, autoimmune diseases, chronic pain and diabetes can all affect concentration and memory, either through inflammation, fatigue or the condition itself,’ Dr Punam explains.

Mental overload

Sometimes, the reason behind your brain fog is quite simply that your brain has had enough – and it needs you to slow down. ‘Many women are trying to excel at work while raising happy children, navigating ageing parents’ declining health and managing households – but neglecting themselves in the process,’ says Dr Punam.

‘Sometimes brain fog is your brain’s way of telling you it’s overloaded,’ she adds. ‘We shouldn’t underestimate the impact that sustained overload has on cognitive function.’

How to work out what’s causing your brain fog

Even with a list of possible causes in front of you, figuring out what’s behind your brain fog can prove difficult – especially when multiple factors could be to blame. The important thing is to avoid assuming it’s one thing without properly ruling out other potential causes first.

‘I always encourage people to look at the bigger picture rather than assuming it’s ‘just menopause’ or ‘just getting older’,’ Dr Punam recommends. ‘Ask yourself when it started. Is it linked to changes in your menstrual cycle? Are you sleeping well? Have you been feeling more anxious or overwhelmed than usual? Have you started any new medication? Are there other symptoms like weight changes, heavy periods or persistent fatigue?’

It’s also important to check in with a healthcare professional to rule out any underlying conditions. ‘If brain fog is persistent, worsening or affecting everyday life, it’s worth speaking to your GP,’ says Dr Punam. ‘Depending on your symptoms, they may recommend blood tests to look for things like thyroid disease, iron deficiency or vitamin deficiencies, alongside exploring menopause, mental health or other underlying conditions.’

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Prioritising your brain health and wellbeing

If you’re struggling with brain fog, you’re not alone and help is available. ‘Brain fog can feel isolating and, as well as medical factors to consider, it’s worth stepping back and reflecting on everything happening in your life,’ Dr Punam suggests. ‘Recognising when you’re trying to hold too much at once is the first step to protecting your own independence, looking after your own wellbeing and supporting your brain health.’

‘The reassuring thing is that brain fog is incredibly common, particularly in midlife, and very often there’s more than one contributing factor,’ she adds. ‘Once you identify what’s driving it, there are usually practical steps that can make a real difference.’