Despite their wealth and fame, it is hardly surprising that professional cyclists have struggled with depression – especially if the damaging effects of doping are added to the mix

Anybody who watched the 1996 Tour de France remembers stage 16, the 199km route from Agen and Lourdes-Hautacam, which at 1,560m is one of the highest paved roads in Europe and one of the toughest climbs in the Tour. When 8km from the finish line, Bjarne Riis – a 10-year pro with modest palmarès and a reputation as a good road captain (so good that Madiot tried to sign him and Fignon sought him out as a team-mate) – dropped to the right hand side of the road, deliberately losing position in the process, coming almost to a standstill while he scrutinised the faces of his rivals.

It's one of the Tour's great jawdropping moments, the way the great Dane – shepherded by a young domestique called Jan Ullrich – forensically appraised his rivals, their demeanour, their gearing, assessing whether they were on the limit. When he made his attack, it was with indecent ease – cruising away then easing up, tempting the peloton of favourites three times before deciding to make it stick and rocket off up the road to take a stage win in the Yellow Jersey, the first rider to do so since Fignon in 1989.

It was, quite literally, an unbelievable display.

Willy Voet put the haematocrits of the Festina team at 54% that day, when the old 50% rule was in place. Not for nothing was Riis nicknamed "Mr 60%". He set a power record for an effort in excess of 30 minutes on a climb, peaking at 526 watts. Only Alberto Contador has ever knocked out more watts on a climb.

Riis had taken advice from his old team-mate Fignon, who knew what it was like to watch a slender lead evaporate and cost him the Tour. Fignon was complimentary about the Dane's qualities as a rider – "He could do anything, go fast when he had to and go through a gap with perfect timing" – but the praise was qualified: "He had a 'big engine', but this has to be made clear: he was a good rider but not capable of winning a Tour de France in normal circumstances."

"He's never a man you'd think of as a great climber" pondered Paul Sherwen as he commentated on the events unfolding on the mountain. "Like a man possessed!" thrilled Phil Liggett. Indeed he was – in 2007 he finally admitted that he had used the performance-enhancing drug EPO to win the 1996 Tour. His name stands in the record books because his admission was outside the time limit for UCI sanctions. At a press conference he said: "My jersey is at home in a cardboard box. They are welcome to come and get it. I have my memories for myself."

But Riis claimed doping was just one part of the puzzle – that weight-loss and harder training were equally as important, and that the win on Hautacam was as much due to his gearing as anything else. He paid great attention to the kind of details that would later become known as "marginal gains". But "Mr 60%" was a cycling pharmacy – not just EPO, but Human Growth Hormone (although he said it left him feeling "blocked"), cortisone and Prozac, which he claimed added an important mental edge, were all key to his preparation for that defining moment in 1996.

Earlier this month Danish TV aired a documentary on the former champion detailing his battle with depression. Entitled Riis – Forfa (Riis – From the Front) it gives an intimate portrait of the man who has been under pressure from allegations by Tyler Hamilton and Michael Rasmussen that he was fully cognisant of, and instrumental in, their doping at Team CSC. Riis is quick to also cite "baggage from my childhood that I've never worked through" including his own doping confession and the deaths of his parents.

There is strong evidence that certain forms of doping – particularly amphetamines, cannabinoids, beta blockers and steroids – can lead to depression. But the equation between doping and depression is not that simple. When German Sport Aid surveyed a number of elite German athletes they found that 88% of them felt that the pressure they were under to succeed – or to raise their profiles or to profit from their success – was a motivating factor in decisions to dope. Over half spoke feeling "existential angst".

Regardless of whether we cast a cynical eye over such results, high stress levels are often a precursor to depression, especially when other factors – genetics or chemical imbalance – are already present. Add in grief or loss, shame and guilt – the death of a parent, a lost career or one spent breaking the rules, or being caught – and the mixture is a combustible one. Jesús Manzano, the cyclist turned whistleblower, brutally has outlined the mechanics of stress, doping and depression:

The drugs lead you to other addictions. The anti-depressants almost automatically accompany other doping treatments. I took up to eight pills of prozac a day when I was racing... Prozac cuts the appetite, keeps you in another world, a world where you're not afraid of what you're doing. You're no longer afraid to inject yourself with all the crap. It takes you to a world where you don't ask any more questions, especially you don't ask your doctor questions either or your sporting director. Then there are periods where you must stop doping you feel like superman. Then one day all of the sudden it stops and you become dramatically depressed. Look at Pantani, Vandenbroucke and all the others we don't even talk about. They are numerous other cyclists and former cyclists that are addicted to cocaine, heroin and other medications. It's not just in the world of cycling.

When René Pottier won the 1906 Tour de France he earned the nickname "King of the Climbers". He was the only rider in the 1905 Tour to pass the summit of the Ballon d'Alsace without having to get off and push his bike. Henri Desgrange said of his feat: "It is one of the most enthralling things I've ever seen." Lucien Le Petit-Breton gave an insight into the psyche of a professional bike rider when he noted:

He arrives, always correct, but reserved, with a serious demeanour, unfathomable! It's impossible to know what he's feeling. He looks at me in a certain way and I think he's thinking 'there's the famous Petit-Breton. Everyone applauds him. Therefore I must beat Petit-Breton.' None of this is based on anything concrete and I know I'm just giving myself ideas but it's impossible to stop my imagination from racing and when a rider's imagination starts racing then it doubles the nervous fatigue… Pottier is absolutely superior… the guy intimidates me, he makes me nervous, I'm crushed. With Pottier, nine times out of 10, I'm already beaten.

In 1906 Pottier's domination was complete – he again won on the Ballon d'Alsace (by 48 minutes), took five of the 13 stages including four on the trot, and three of those with solo breakaways – of 250km over the Ballon d'Alsace, 130km into Grenoble and 325km on the stage to Nice. He secured the overall victory with a win on the final stage into Paris. The unofficial "King of the Mountains" had slaughtered the opposition and stood triumphant on the top step of the podium in the Parc des Princes.

Six months later he was dead.

He won his last race, the Bol d'Or at the Buffalo velodrome, in September. A reporter for La Vie au Grand Air described him as "always regular, always serious – he wins without showing any joy, silent, severe and obstinate".

On 25 January 1907 his mechanic found him hanging from the hook he used to store his bike. His brother spoke of how he was unlucky in love. There were whispers that his wife had started an affair while he was away riding the Tour. The papers decided that the "unlucky in love" narrative would shift the most copies. The real reasons for his suicide were never established. No note was ever found. He was known as 'the man who never laughs.' Perhaps, like so many others after him, he simply got tired of riding with the black dog always on his wheel.

When champions stop, there is no one to be with them, so it's particularly hard to go from climbing a podium to facing the grind of daily life. It's not surprising that they go into the abyss.

The list of professional cyclists with depression is a long and largely tragic one. Some, like Graeme Obree and Bradley Wiggins, have learned to deal with it and have gone on to greater things, but many – Marco Pantani, Frank Vandenbroucke and José María Jiménez to name a handful – never escaped the black dog.

The National Institute for Health and Clinical Excellence define depression as:

"A wide range of mental health problems characterised by the absence of a positive affect (a loss of interest and enjoyment in ordinary things and experiences), low mood and a range of associated range of emotional, cognitive, physical and behavioural symptoms. Distinguishing the mood changes between clinically significant degrees of depression (for example, major depression) and those occurring 'normally' remains problematic and it is best to consider the symptoms of depression as occurring on a continuum of severity."

The most commonly recognised factors that increase vulnerability to depression have been identified as "gender, genetics, family factors, adverse childhood experiences, personality factors and social circumstances". In their stress-vulnerability model, the academics Keith Nuechterlein and Michael Dawson identify the interaction of these vulnerability factors with social or physical triggers as the precursors to a depressive episode.

It hardly seems surprising that professional cyclists, despite their wealth and fame, would be vulnerable to depression: the endless scrutiny, the life lived on a knife edge between optimum fitness and over-training, the constant flirtation with loss. Imagine having dedicated your life from an early age to the pursuit of excellence with all its attendant pressures while never developing the ordinary coping mechanisms that "real life" are so good at teaching the rest of us.

Imagine being 22-year-old Jonathan Breyne, who tested positive for clenbuterol after a failed test in China, unable to eat because you have no appetite, making yourself ill as your world falls apart around your ears, the only world you've ever known, driven to attempt suicide because of comments on internet forums.

Or Mauro Santambrogio, who turned professional aged 20, working in a night bakery, alone with your darkest thoughts, tweeting your suicide note. Imagine having hundreds and thousands of words, of scathing comments forensically dissecting your worst decisions, your biggest mistakes.

But where you and I might talk to friends and family or seek professional help, cyclists exist in a bubble where their physical condition and ability to perform is paramount. Subjected to high levels of physical stress, there seems to be little or no framework to support riders to deal with the mental consequences of that stress.

Despite the smirks and knowing winks that greet the phrase "marginal gains", Dave Brailsford is not wrong when he credits the appointment of Dr Steve Peters as the best he has ever made. In the words of Wiggins, he is "the world expert on common sense" and the man he credits with "opening my eyes on how to approach my worries and fears". Peters was part of the team that turned the depressed Olympic track rider into the 2012 Tour de France champion.

Perhaps Obree put it best: "It's not that sport makes people depressed. A lot of people who suffer from depression have a tendency to have obsessive behaviour – that's why more of them exist in the top end of sport. The sport is actually a self-medicating process of survival."

When Franck Vandenbroucke died in Senegal the pathologist wrote "natural causes" on the death certificate. But the Belgian's life had been a litany of drug use, dysfunction, suicide attempts and depression. A difficult relationship with his parents, a childhood accident and lengthy convalescence, turning pro at 19, cocaine addiction and doping all put him off the scale on Neuchterlein and Dawson's stress-vulnerability model. In his biography, the Belgian was candid about his drug habits:

"To Stilnoct and amphetamines, I added Valium… Sometimes I didn't sleep a second in five days. I started seeing things, people who didn't exist. I used to hear them coming. They were coming to arrest me."

When he attempted suicide – with insulin – in 2004, his note was simply and direct: "Please don't let them open my eyes."

Like most professional riders of the era, Vandenbroucke's recreational and PED use coupled with his chaotic personal life was a perfect storm that put him at high risk of developing depression. Others, like Tyler Hamilton, who was diagnosed with clinical depression in 2003, may show a more classic predisposition with a well-established family history – his grandmother committed suicide when his mother was 13. But the drugs, at least the performance enhancers, don't help.

The Usada reasoned decision outlined the secret of US Postal's success: a catalogue of performance enhancing drugs including testosterone, EPO, Human Growth Hormone and cortisone. None of these substances are depressives in themselves (rapid withdrawal from testosterone has been linked to depression while recent studies indicate that EPO may have a therapeutic use in its treatment), but their abuse in the preparation of professional athletes can lead to stress situations that trigger the condition.

In their 2002 paper about overtraining, Armstrong and Van Heest note that "overtraining syndrome and clinical depression involve remarkably similar signs and symptoms, brain structures, neurotransmitters, endocrine pathways and immune responses".

In 2007, a study was published in the European Journal of Applied Physiology that showed that EPO use by a group of fit amateur cyclists improved time-to-exhaustion by a massive 54% after four weeks. Imagine the implications for an elite cyclist training for an endurance event like a Grand Tour. Coupled with a rise in peak power output over the same period of 13%, you can begin to see how Riis powered away so effortlessly on Lourde-Hautacam, or how Pantani virtually sprinted up the Alpe, or how Armstrong motored to Sestriere and why EPO, and then blood transfusions and microdosing the EPO test became the dope du jour in the professional peloton.

Now factor in Human Growth Hormone – which replaces fat with muscle to help optimise body-fat ratios, aids muscle recovery and may improve the connectivity between muscles to help prevent injury – steroids such as testosterone, which stimulates the body's own production of EPO and helps muscle recovery, and cortisone, which dramatically reduces swelling and inflammation to aid recovery. Armstrong wasn't lying when he said he trained harder; he was simply economical with the truth about how he enhanced his ability to do so.

To riders already pushed to their physical limits, factor in the ever-present spectre of loss – of an important race, a contract, even a career – and the vicious cycle of doping and depression binds ever tighter. And if you think US Postal were alone in their pharmacology, think again. That litany – EPO, blood doping, HGH, testosterone and cortisone – is the hymn-sheet that elite cycling was singing from, including teams like Bjarne Riis's CSC.

When l'Equipe published the Index of Suspicion it was accompanied by an article on cortisone abuse by Dr Guillaume, who claimed that the use of corticosteroids was as widespread as it had been in the 1970s and 1980s, when it wrecked the knees of many great cyclists. Jesús Manzano claims he was injected daily and can no longer ride a bike because of the damage from prolonged cortisone abuse.

Cortisone sits at that uncomfortable intersection between recovery and doping to win, situated on the graph somewhere between definitely unethical and not quite illegal. In his book The Normal and the Pathological Georges Canguilhem speaks of the "physiological bravado" of athletes who embody the desire for "life to go beyond the codified biological constants" and into unknown territory – just how much suffering can one man take on a bike when weather and terrain and the limits of his endurance are against him? And should we begrudge those riders, who are, after all, doing this for our entertainment, the right to alleviate their suffering with a little white pill?

Doping isn't a new phenomenon; it's nearly as old as professional sport itself. And there exists an implicit understanding that professional athletes stand outside the supposed ethical constraints placed on amateurs (tell that to the US Masters racing scene). Coupled with a lack of understanding of the long-term health implications of PED abuse, professional cyclists have considered their drug use both countenanced and abnormal. But societal attitudes are changing – both towards drugs and public health. Coupled with an explosion in pharmaceutical discoveries, cyclists can now both dope better and find themselves under increased and unaccustomed scrutiny for doing so.

The question remains: should a doctor administer drugs to a healthy individual? And does a line exist between helping riders recover from the demands of bike racing (even in the modern era) and using drugs to create a superman who can deal with the rigours of that sport? And by whose moral code is using cortisone considered to be unethical?

What remains problematic is the lack of a holistic approach to a rider's health. Patten's study of the link between exogenous corticosteroids and major depression in the general population concludes that "persons taking corticosteroids have a higher frequency of major depression than non-exposed subjects".

Extrapolate this to a peloton where high levels of cortisone use and abuse are reported to exist and you could have a ticking bomb – how soon before we see a further raft of riders not just with dodgy knees but major depression? In his confessional press conference, Riis admitted to taking cortisone over a period of six years.

No wonder Dr Guillaume cites prozac as one of the most frequently used medications in modern sport. But it's not only professional cyclists who know about riding with the black dog. In his excellent piece Cycling and depression – finding a balance, the cycling blogger @spandelles writes:

I have become more aware of the tightrope I walk in relation to cycling: it does make me feel good more often than not, but I have also had experiences before, during and after rides where I have had quite extreme negative episodes which do not seem to be coincidental. Sometimes the stress of getting ready to go out on a ride seems to be a trigger. Sometimes I have had to stop by the side of the road, completely numb; and sometimes after a ride I have felt like I never want to ride again. I know what the bonk feels like, and I know that these feelings, although sometimes brought about by exertion (or its anticipation) are different.

Exercise has become the panacea for depression in recent years, cited as a way of regaining control of your body when you feel you are no longer in control of your life. Physical exercise can be a mood enhancer when physiological changes in levels of endorphin and cortisol – the "stress" hormone – occur.

But consider if your symptoms include fatigue or lethargy or if you have a tendency to guilt or self-blame at perceived failures in sticking with an exercise regimen. The conclusion of a 2013 review Exercise for Depression suggests that exercise might have a moderate effect on depression, but that this may only be small and that the data on whether benefits persist when exercise stops is virtually non-existent.

But the anecdotal evidence from recreational cyclists and bloggers is overwhelmingly in favour of the beneficial effects of getting out on your bike and riding the black dog off your wheel. In his Kickstarter pitch for his book Cycling through Depression, Ed Bradley states:

If a 53-year-old, out of shape, overweight, depressed man, whose life has come apart can cross the USA on a bicycle, then anyone can overcome their depression to achieve their goals and dreams.

However, like @spandelles, Obree sounds a note of caution: "I recommend cycling to help people feel better, but not to deal with the underlying causes, which could be a repressed memory, resentment from childhood, relationships. These need to be dealt with."

And still the stigma remains; over a hundred years after Pottier hanged himself from his bike hook, what has changed? How many teams employ a psychiatrist? Where is the support to counsel riders who dope and are caught doping, whatever their motivation? Where is the desire to look at a rider's health holistically? Whatever your opinion of Riis and his motivation for speaking up about his depression, he remains one of a handful who have spoken out and sought help.

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