Lewis Wolpert: 'The immune system can have profound effects on thinking and emotion'

I had persuaded myself that depression was related to abnormal sadness, hence my book, Malignant Sadness. But I now realise that I might have missed a very important aspect of depression, its relationship to the immune system. Friends did try to persuade me to take it seriously, but to no avail. Then I read an article in a leading medical journal that described the treatment of hepatitis with alpha interferon. I was struck by the fact that they gave such patients an antidepressant at the same time, for otherwise there was a high incidence of depression. I contacted the authors in the USA and they told me that their patients' depression was not related to sadness, but more to fatigue. They also sent me a review which has persuaded me how important the immune system may be in depression.

That there is a relationship between physical and psychological health goes back to the ancient Greeks, but it is only quite recently that it has been recognised that the immune system can have profound effects on thinking and emotion. One link is via stress. The stress response is adaptive in many situations, such as danger, and helps the individual to deal with the threat. The physiological response involves both hormones and the nervous system, and makes more energy available. However, this becomes a danger to health when it remains chronically overactive, and this condition is frequently found in patients with severe depression.

Stress and depression can affect the immune system, which is complex, with many interactions between cells such as lymphocytes and macrophages, those white cells that are at the core of the immune system, and numerous cytokines, the chemical signals between these and other cells. Chronic stress can affect the function of lymphocytes and cytokine production, and a longer time is needed to recover from an infectious disease. Surprisingly, the same stressors can also activate the immune system.

There is now evidence that depression can both activate and suppress immune-system function. With immune-system activation, there can be induction of a state that is called sickness behaviour, which resembles depression. It is this that underlies the depression caused by giving interferon, which is itself a cytokine controlling aspects of the immune system. The similarity of depression with sickness behaviour predicts that those with illnesses should have higher rates of depression. This is the case.

Increased cytokine levels after birth could account for postnatal depression. How the cytokines act on the brain to cause depression is not clear, but they can enter the brain. Stress hormones such as cortisol are very likely key players, as depression in many is associated with an increase in the activity of the interactions between the hypothalamus, pituitary and adrenal glands, which are activated by stress. Increase in cytokines can stimulate this system, and the normal negative feedback that returns it after a short while to normal function may be prevented from operating.

There is a further fascinating connection with the placebo effect. In his new book, Placebo, Dylan Evans argues that the acute phase response is involved. This response is a result of some injury and the immune system is activated, moreover only those illnesses that involve this response are capable of being relieved by the placebo effect, and they include depression. The complexity of all these interacting factors is disturbing, but will eventually lead to new drugs for depression, perhaps acting on the immune system.

Lewis Wolpert is Professor of Biology as Applied to Medicine at UCL

Start your day with The Independent, sign up for daily news emails
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Pre-Press / Mac Operator / Artworker - Digital & Litho Print

Negotiable: Recruitment Genius: With year on year growth and a reputation for ...

Recruitment Genius: Project Manager - Live Virtual Training / Events

£24000 - £28000 per annum: Recruitment Genius: A Project Manager is required t...

SThree: Trainee Recruitment Consultant

£18000 - £23000 per annum + OTE: SThree: SThree Group has been well establishe...

SThree: Trainee Recruitment Consultant

£18000 - £23000 per annum + OTE: SThree: SThree Group has been well establishe...

Day In a Page

The difference between America and Israel? There isn’t one

The difference between America and Israel? There isn’t one

Netanyahu knows he can get away with anything in America, says Robert Fisk
Families clubbing together to build their own affordable accommodation

Do It Yourself approach to securing a new house

Community land trusts marking a new trend for taking the initiative away from developers
Head of WWF UK: We didn’t send Cameron to the Arctic to see green ideas freeze

David Nussbaum: We didn’t send Cameron to the Arctic to see green ideas freeze

The head of WWF UK remains sanguine despite the Government’s failure to live up to its pledges on the environment
Author Kazuo Ishiguro on being inspired by shoot-outs and samurai

Author Kazuo Ishiguro on being inspired by shoot-outs and samurai

Set in a mythologised 5th-century Britain, ‘The Buried Giant’ is a strange beast
With money, corruption and drugs, this monk fears Buddhism in Thailand is a ‘poisoned fruit’

Money, corruption and drugs

The monk who fears Buddhism in Thailand is a ‘poisoned fruit’
America's first slavery museum established at Django Unchained plantation - 150 years after slavery outlawed

150 years after it was outlawed...

... America's first slavery museum is established in Louisiana
Kelly Clarkson: How I snubbed Simon Cowell and become a Grammy-winning superstar

Kelly Clarkson: How I snubbed Simon Cowell and become a Grammy-winning superstar

The first 'American Idol' winner on how she manages to remain her own woman – Jane Austen fascination and all
Tony Oursler on exploring our uneasy relationship with technology with his new show

You won't believe your eyes

Tony Oursler's new show explores our uneasy relationship with technology. He's one of a growing number of artists with that preoccupation
Ian Herbert: Peter Moores must go. He should never have been brought back to fail again

Moores must go. He should never have been brought back to fail again

The England coach leaves players to find solutions - which makes you wonder where he adds value, says Ian Herbert
War with Isis: Fears that the looming battle for Mosul will unleash 'a million refugees'

The battle for Mosul will unleash 'a million refugees'

Aid agencies prepare for vast exodus following planned Iraqi offensive against the Isis-held city, reports Patrick Cockburn
Yvette Cooper: We can't lose the election. There's too much on the line

Yvette Cooper: We can't lose the election. There's too much on the line

The shadow Home Secretary on fighting radical Islam, protecting children, and why anyone in Labour who's thinking beyond May must 'sort themselves out'
A bad week for the Greens: Leader Natalie Bennett's 'car crash' radio interview is followed by Brighton council's failure to set a budget due to infighting

It's not easy being Green

After a bad week in which its leader had a public meltdown and its only city council couldn't agree on a budget vote, what next for the alternative party? It's over to Caroline Lucas to find out
Gorillas nearly missed: BBC producers didn't want to broadcast Sir David Attenborough's famed Rwandan encounter

Gorillas nearly missed

BBC producers didn't want to broadcast Sir David Attenborough's famed Rwandan encounter
Downton Abbey effect sees impoverished Italian nobles inspired to open their doors to paying guests for up to €650 a night

The Downton Abbey effect

Impoverished Italian nobles are opening their doors to paying guests, inspired by the TV drama
China's wild panda numbers have increased by 17% since 2003, new census reveals

China's wild panda numbers on the up

New census reveals 17% since 2003