I asked my mother’s neurologist what caused her stroke. ‘Depression,’ he said

Anthea Rowan
Anthea Rowan with her mother Lala, before her dementia diagnosis

When I asked my mother’s neurologist what caused her stroke – she bore no evident cardiovascular risk – he said, “depression.”

I must have looked blank because he elaborated: “She sat still for too long, and a clot formed.” It lodged in the left occipital lobe of her brain, and she lost her ability to read.

Depression, says Professor Craig Ritchie, the chief executive and founder of Scottish Brain Sciences, “may well be an upstream trigger for physical health”. It might even have been a significant risk factor for the Alzheimer’s disease that my mother suffered from in the last six years of her life.

People may present with depression later in life as a consequence of dementia but increasingly, research points to depression in early and midlife as a risk factor for developing dementia.

They may, in fact, be twice as likely to be diagnosed with dementia if they battled with depression in early and midlife, according to a recent study, which followed 1.4 million Danish men and women for more than 40 years.

Holly Elser, a neurology resident at Penn Medicine and the lead author of the Danish study, says “There are lots of things happening in the brains of people with depression, including changing levels of serotonin, noradrenaline and dopamine, which all drive changes in the brain.”

My mother’s first episode of depression happened when she was 38. I remember this because I noted it in my 13-year-old diary in round, childish handwriting: “Mum doesn’t feel well.”

From then, until the time her dementia presented in her 70s, she was lucky to get away with an episode a year, and those lasted anything from three months to the two-year-long episode when “she sat too still for too long”.

She continued to suffer throughout her life – her diagnosis, major treatment-resistant depression. She had treatment, which back in the 1970s, meant old-fashioned drugs and ECT.

My mother used to say depression was like living behind glass: you could see life, but you couldn’t hear it or touch it. And it didn’t touch you: she said everything abandoned her in depression, interest, joy, “even interest in my children”, she said sadly.

Anthea Rowan with her mother Lala
Anthea Rowan with her mother Lala, who described depression as 'living behind glass'

There’s a word for it that’s used in the clinical diagnosis of depression: anhedonia. If she couldn’t reach us, we couldn’t reach her. She stopped cooking with us, stopped wanting to walk with us, just stopped. I grew to dread the mornings when she didn’t get up, morning after morning for months at a time.

There was never any obvious trigger. They came, they went, apparently for no reason. We lost her to them. She always came back though. Not with dementia, with dementia there’s no coming back. I never imagined there might be a link.

Prof Ritchie elaborates on the pathology. When a person is battling with depression, he says, the stress hormones in their brains are at elevated levels that could result in “damage to nerve cells”.

“There’s an argument that not only does cortisol – the stress hormone – have a direct toxic effect on nerve cells, it also can underpin the development of Alzheimer’s disease, by  driving the production of the type of amyloid beta from the normal amyloid precursor protein (APP), which lays the foundation for amyloid plaques – the pathological marker for Alzheimer’s.”

But – and he is at pains to emphasise this – these processes don’t happen overnight. A handful of depressive episodes are unlikely to have a lasting impact on the brain, he says. We’re talking about “chronic exposure”, months, years – for it takes years for the body’s natural resilience to be overwhelmed, he says – of the brain being “steeped” in stress, just like it takes years of eating badly, years of sugar overload, to expose a person to the risk of Type 2 diabetes.

I have had many conversations with Dr Dorina Cadar, a senior lecturer in cognitive epidemiology and dementia at Brighton and Sussex Medical School, about both dementia and depression; we also share a common, personal experience: a parent who suffered from both. Depression, she says, is associated with “chronic inflammation and vascular issues” which may – over time – contribute to the cognitive decline seen in dementia.

Anthea Rowan (far right) with her mother Lala (centre), sister Carol (front centre) and brother Rob (left)
Anthea Rowan (far right) with her mother Lala (centre), sister Carol (front centre) and brother Rob (left)

Dr Cadar’s father experienced episodes of depression in midlife that were left untreated. Although he had strong family support, he dealt with long and intense periods of stress as part of his political career, working for the local government. “My mum and I always asked ourselves what might have caused his dementia. Was it depression? Was it something else? It was probably – as is the case in most people who are diagnosed with dementia – a combination of risk factors; depression is just one more.”

The impact of hormones and why women are at greater risk

What about the fact that women are more likely to suffer from either of these conditions than men, though. Why is that? Probably a combination of things, says Dr Cadar – women tend to live longer, and dementia usually presents in old age.

Then there’s the hormonal rollercoaster women live with through menstruation, pregnancy, postpartum and menopause, which can all influence mood and contribute to a risk of depression, which then predisposes women to prolonged states of inflammation and increased risk of subsequent dementia, she adds.

But just as Dr Cadar observes, depression was only one possible risk factor for her father’s dementia, so depression is not only about low moods. My mother didn’t just feel anxious: she stopped sleeping properly, stopped exercising, stopped socialising, and withdrew completely, often into books.

All of these are modifiable risk factors for dementia. When she had her stroke and lost her reading, it was as if a plug had been pulled out of her cognitive reserve and her intellectual dam drained; unable to engage easily via the medium of the written word anymore, she grew ever more isolated.

As Gill Livingston, a professor of psychiatry of older people at UCL, says: “Depression is related to reduced self-care and social contact, so these may lead to an increased risk of dementia from illnesses and isolation.”

And, as Dr Cadar reminds me, isolation is dangerous because social engagement is cognitively stimulating. Limit that, and you deplete your brain and cognitive reserves.

Anthea Rowan
An old photograph of writer Anthea Rowan with her parents and siblings

Prof Livingstone describes the experience of a patient who suffered “recurrent depressive episodes and later dementia”, but between those episodes, “was so well – interested, intelligent, loving and active”. I think of my mother, whose frequent episodes first presented in 1978, more than a decade before World Mental Health Day started in 1992 and more than two decades before the UK’s Mental Health Foundation launched Mental Health Awareness Week.

In the UK, almost one million people have dementia. “A number that’s expected to rise sharply in the coming years,” Dr Cadar warns. Dementia and Alzheimer’s disease were the leading cause of death in England and Wales for the first time in 2022. Cases of depression are on the rise too, according to a 2021 study, which found an increase in prevalence globally.

But, as Prof Ritchie says in a hopeful note, there is better knowledge of mental illness today, faster diagnoses and better treatment, which has been improved with drug development and effective talk therapies.

Livingstone refers me to a large UK Biobank study of interventions for depression – 354,313 participants followed for 12 years – which found, yes, that people with a diagnosis of depression bear a higher risk of developing dementia but this risk is reduced if their depression is treated.

“It is important to energetically treat people with depression to improve mood, quality of life, ability to function and, for a few people, to save their life,” says Prof Livingston. “The evidence is that people treated in midlife are less likely to develop dementia in the future and so treating now helps people avoid the illness which is most dreaded by people in midlife – dementia.”

Anthea Rowan
Anthea's mother Lala, pictured here with her three children, could have been at risk from dementia in part due to depression

In the 1970s, when mental illness wasn’t as swiftly spotted, my mother described visiting her GP several times, complaining of tiredness, loss of appetite and sleep, before presenting him with a definition of depression from the Oxford English Dictionary because that sounded how she felt, “You don’t think I could have this, do you?”

The Danish study found the risk of dementia was higher in individuals with in-patient admissions for depression – like mum – and especially for men. Probably because they are less likely to seek help.

Does knowing all this help now? It’s too late for mum. Would the outcome have been different if she’d understood the risk depression might bring to bear on the health of her brain later? It isn’t that simple – you can’t just will yourself to wellness when you are struggling with depression.

But the treatments available to her in the 1970s were very limited, awareness was almost non-existent. I often think she didn’t stand a chance. Today’s generation – my generation? We do.


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