The breakthrough came with a pine marten. These creatures have seldom helped me before in my life.

But on this occasion, they were unusually obliging. They proved to me that testosterone replacement therapy was working for me in ways far beyond the sexually obvious.

Let me explain. ‘Pine marten’ was the answer to a crossword clue that read, ‘Caledonian Mustelid’ (4,6). And whereas, at any point over the last few years it would have taken days for my brain to grudgingly, if at all, give me the solution, this time my grey matter gave me the answer in seconds.

My improved crossword performance came seven weeks into a pill-popping regime that, as I write these words, is rolling back my fears about advancing in deracinated form into my 50s; the era that Martin Amis famously called ‘the crap decade’ for men.

I had heard that testosterone replacement therapy could rejuvenate me – not just my libido, but my physical strength, cognitive skills and concentration levels.

I’d been feeling for a while that my brain wasn’t pulling its weight in the way I expected it to be. After all, I’m 46, not 86 years old, so constantly forgetting to charge my phone, sleeping in the afternoon and struggling with crosswords all felt a little premature.

There’s been a surge in the numbers of men using testosterone replacement therapy (TRT) over the last few years. The NHS reported a 15 per cent rise in testosterone prescriptions between 2021 and 2022.

Some of this can be explained by the effect of social media content about men and masculinity – caused by (or perhaps the symptom of) the rise of headline-grabbing toxic influencers such as Andrew Tate.

Rob Crossan's improved crossword performance came just seven weeks into testosterone replacement therapy – an encouraging sign it was working

And it seems that male concerns about collapsing testosterone levels have genuine scientific probity.

According to results published in the Journal of Clinical Endocrinology & Metabolism, average testosterone levels in adult men worldwide fell by one per cent each year between the 1970s and the mid-noughties. A 65-year-old man in 2002, for example, had testosterone levels 15 per cent lower than those of a 65-year-old in 1987. We don’t yet know what this means for men in 2025, but the curve thus far is hardly encouraging.

More worrying still, in March a survey of 2,000 men with the condition revealed that a quarter waited five years before seeking treatment, hoping that exercise and improved diet would do the trick.

So, I decided to give TRT a try, in what, at first, I believed would be an almost certainly doomed attempt to raise my physical and mental game. My fiancee, an ICU nurse at a central London NHS hospital, was equally sceptical, telling me that I should consider simply going to the gym a bit more before embarking on a course of this kind.

But I already felt that the running and rowing machines couldn’t save me. I was tired all the time. I was sleeping ten hours-plus a night. My vocabulary had shrunk. As for my libido; it hadn’t collapsed exactly, but in my mid-40s I’d expected I’d be initiating sex with my fiancee or be at least open to her advances a few more times a week.

My salvation, I hoped, was the Centre For Men’s Health (CMH) in London’s Harley Street. Beyond a gleaming reception area filled with expensive sofas and equally expensive looking receptionists, I found the office of Dr Anand Patel, a consultant who is also a board member of British Society of Sexual Medicine.

He explained that 40 per cent of men over the age of 45 have low testosterone.

A surge in the numbers of men using testosterone replacement therapy over the last few years could be attributed to the rise in toxic influencers such as Andrew Tate, Rob writes

‘Getting older is normal,’ Dr Patel said, but meekly accepting cognitive decline isn’t. ‘You wouldn’t tell a woman going through the menopause that her symptoms are normal and she should put up with it and not ever be offered HRT. If there are symptoms then help is available and so that approach should apply to men too.’

Dr Patel listed my symptoms before I did: muddled thinking, low motivation and, yes, a reduced sex drive. Those crossword struggles, not to mention remembering names, had resulted in a default mood setting of feeling anxious and groggy.

A few days before the consultation, I had the first of two blood tests designed to pinpoint my testosterone levels – and general health.

The CMH is nothing if not thorough. Among other things, my cholesterol, blood count, kidney and liver functions were analysed. The results, which came a few days later, confirmed that, while I was in generally good shape, my testosterone levels were pretty rubbish.

‘You’re at 11.2 nanomoles per litre,’ I was told by Dr Patel, his genial tone becoming more lugubrious for a moment. ‘A lab definition of low is 7.6. However men can often experience symptoms under a total testosterone 15 and in some cases even higher. So your testosterone is low, but on the high end of low.’

In football terms, this was relegation form. Though, strangely, this news didn’t implode my ego for good. At least now I knew I wasn’t imagining it. I had a problem.

‘Some men feel this is an assault on their masculinity,’ Dr Patel told me. ‘But all it really means is that your brain is being a bit lazy and your testicles could probably do a little more.’

As low as my score is, I probably wouldn’t qualify for treatment on the NHS.

Dr Anand Patel is a consultant at the Centre for Men's Health in Harley Street, London

Dr Patel told me patients often wait a year on the NHS and some aren’t considered for testosterone treatment at all, mainly due to the strict criteria some doctors use. Many don’t consider the problem serious enough, even when a man’s testosterone levels have reached a level at which symptoms would be noticeable.

Currently there are no guidelines produced by the National Institute for Health and Care Excellence (NICE) for testosterone dysfunction. The CMH instead follow evidence-based protocols issued by the British Society for Sexual Medicine.

But by this stage, my mind was pre-occupied with other concerns. What about aggression? Will a testosterone treatment turn me into a minor Sopranos character; ready to start punching things with the power of a barn door being slammed shut in a typhoon?

‘If you weren’t aggressive in your teens and twenties then you won’t be aggressive now,’ Dr Patel reassured me. ‘All that’s happening is that your testosterone levels are returning to what they were when you were a young man.’

I’m given a choice of treatment: either injections (which I can administer at home or come into the clinic to have) or pills. These work by increasing my own natural testosterone without it bothering my overall hormone regulating system.

I hate needles so I decided to take the pills, called Clomid. I was instructed to take half of one every other day.

Two weeks later and I was sitting on the sofa, wrapped in a blanket, listening to Frank Sinatra ballads and clasping a mug of tea in both hands while looking out of the window with a ‘nobody can possibly understand my private pain’ look.

My fiancee, returning from another 12-hour shift as an ICU nurse, quite rightly berated me for, in her words, ‘looking like you’re having the menopause’.

She had a point. But I really did feel horrible. I didn’t want to go out. I didn’t want to see my friends. I had lost interest in sex completely. I was eating far too much cheese.

Two weeks in, I really did feel horrible, says Rob. I didn’t want to go out. I didn’t want to see my friends. I had lost interest in sex completely. I was eating far too much cheese

And now, I feel profoundly tweaked; like an old Vauxhall that’s been given new tyres or a decaying boozer that’s been given a gastro-refurb, he says 

I’d been warned that there may be a slight hormonal bump between commencing the pill regime and feeling better. But this was enervating to the point where I seriously considered quitting the treatment there and then. I didn’t need this. I missed feeling like a bloke. I loved going to pubs. I loved being a good partner. And these pills were making me feel pathetic, a walking, tearful puddle of man-gloom.

But the next day, things began to change. I don’t just mean my recognition of ‘pine marten’ in the crossword. I also noticed, while filing copy to a magazine that I was writing faster and more accurately than I had for years, with fewer spelling mistakes.

That afternoon I had to interview a well-known radio presenter over the phone. It was only after I’d hung up that I realised I hadn’t referred to my list of questions once. I’d memorised them all without even trying.

Over the following few days, it felt like a dull, low-level tempest had lifted its swaddling grasp from me.

I went for a run for the first time in months. I stopped gnawing on economy cheddar. I needed two hours less sleep each night. I started feeling a lot more frisky towards my fiancee and, best of all, my hair hadn’t begun to fall out; a symptom I’d been told was possible when taking testosterone supplements.

‘You’re on the line between assertive and bossy these days Rob,’ my fiancee said last week. ‘But I do like it.’

I could barely hear her. I was busy putting up some shelves. What on earth had happened to me? My fortnight of being Morrissey was turning into a spring time of being, well, if not quite Ray Mears then certainly somebody who didn’t sit around on sofas with blankets on their shoulders.

It’s been seven weeks now since I started the treatment. No, I haven’t developed a six-pack, begun needing sex five times a day or engaged in any ‘roid-rage’ type tantrums. But I feel profoundly tweaked; like an old Vauxhall that’s been given new tyres or a decaying boozer that’s been given a gastro-refurb. The car is still a car. The pub is still a pub. And this man is still the same man. Just an improved one.

There was a clue in my crossword this morning that felt appropriate. The clue was, ‘bravado, daring’. The answer was ‘swagger.’ That’s what I feel I have coursing through me now as I continue my experiment with TRT. And I can think of no better word to counteract the onset of what no longer feels like the upcoming, ‘crap decade’.

Blood tests and consultations at the Centre For Men’s Health start from £800. More info at www.cmh.co.uk