Consultant trichologist Sally-Ann Tarver discusses the science behind laser phototherapy
Millions of individuals around the world suffer from hair loss (alopecia) for various reasons. Genetics often plays an important role but other factors such as hormonal imbalances, stress, nutrition and numerous underlying medical conditions can also greatly contribute to hair loss. Alopecia can cause severe emotional distress, depression, social phobia and anxiety.1 A UK study indicates that approximately 40% of women suffering from hair loss claim to have had marital problems, while 63% have reported career-related issues as well.1 Common hair loss solutions today include FDA-approved medications such as minoxidil (which can be used by both men and women) and finasteride, a prescription drug that is only intended for men. Although widely used in the treatment of hair loss, both also have a small risk of side effects.2,3 Technologically-advanced natural solutions to hair loss that have limited side effects are rapidly gaining popularity amongst hair loss experts and medical practices. In particular, laser phototherapy (LPT) for hair loss is currently used to effectively treat androgenetic alopecia (hereditary baldness) at a cellular level.4,5
The first case of using light to treat a medical condition (lupus vulgaris) dates back to 1903 with the work of Dr Niels Ryberg-Finsen, a Danish physician and scientist who won the Nobel Prize in Physiology or Medicine for his pioneering work on the treatment of disease with concentrated light radiation.6 It was not until 1965 that the first study on LPT was published by Hungarian physician, Dr Endre Mester. While irradiating shaven mice with ruby laser light, he realised that the fur of the exposed mice was growing back more quickly than the control group of the experiment.7 LPT for hair loss is actually a branch of low-level laser therapy (LLLT), also called cold laser therapy. It involves treating human tissue with low-powered (or ‘cold’) lasers to trigger the absorption of low-density energies that are much lower than energies produced by hot lasers. Studies have indicated that LPT has therapeutic effects on human tissue and cells.8 The mechanism of LPT has been thoroughly researched. Evidence suggests that LPT targets cells and positively alters their metabolism with an increase of:10
Ironically, the invention of laser hair removal eventually led to the introduction of LPT for hair loss. This occurred due to paradoxical hypertrichosis, whereby several patients would experience hair growth around areas being treated for hair removal due to light reflecting off the target area at low energies.9,10
In essence, LPT provides energy to hair follicles in the form of laser light. The use of coherent light ensures that the base of hair follicles, buried 3-5mm under the scalp, can be reached and subsequently treated. This involves the stimulation of epidermal stem cells in hair follicle bulges by irradiating the engine of hair cells – organelles – known as mitochondria with energy, which permits them to convert this light energy into chemical energy. This chemical energy becomes available for hair cells to use and grow into healthy, terminal hair.10 The above process defines photobiostimulation or simply biostimulation. Human cells can be stimulated by energy, which triggers therapeutic effects for healing. Since LPT also reportedly shifts hair follicles into the growing anagen phase,11 which optimises the natural hair growth cycle, individuals can also use LPT devices as effective hair loss prevention tools. Side effects are rare and minimal with LPT; a minority of patients can experience headaches, sometimes accompanied by scalp sensitivity. This is due to an augmentation of blood flow to the scalp, which carries additional nutrients to hair follicles. Feelings of scalp tightening have also been reported – also due to increased blood flow. All of these side effects are temporary and improve on their own as patients adjust to renewed blood flow.12 It must be noted here that advanced hair loss patients (Norwood VI and above in males, Ludwig III in females13) may not be candidates for laser phototherapy. However, combining LPT with hair transplantation has been shown to be extremely effective for reasons that shall be examined later.
Clinical studies on successfully treating androgenetic alopecia with LPT are numerous. Overall LPT for both men and women is decidedly safe and effective10 and on average patients experience a decrease in the number of vellus hairs, and an increase in the number of terminal hairs with an increase in shaft diameter.5 Positive changes in the texture and quality of hair have also been reported.6 In a 2013 study,14 40 subjects diagnosed with androgenetic alopecia were enrolled in a 24-week randomised double-blind sham device-controlled experiment. Subjects received 18-minute LPT treatments every day with a sham device or helmet-type home-use device, emitting wavelengths ranging from 630 nm to 660 nm. Progress was monitored using a phototrichogram and global assessment. The LPT group showed a significant increased mean hair diameter and considerably greater hair density in comparison with the sham device group.
Another study conducted in 2014 reports a 35% to 39% hair growth increase in males diagnosed with androgenetic alopecia receiving 25-minute, 655 nm wavelength LPT treatments every other day for a period of 16 weeks.7 More recent reviews9,10 of LPT conducted in 2016 conclude that hair count and hair density can be significantly improved in both males and females undergoing LPT treatment, along with increased hair thickness and tensile strength, leading to high patient satisfaction.
It is important here to mention a few factors that determine whether or not LPT for hair loss will be successful. First, it is crucial that the base of hair follicles are treated since this is where epidermal stem cells are forming. For this reason, the use of light-emitting diodes (LEDs) is not effective for hair restoration. LED lightwaves propagate incoherently and aren’t powerful enough to transverse the scalp. A study published in 1996 to compare the effect on skin blood flow found that coherent laser light increased vasodilation by 54% whereas the non-coherent LED monochromatic light did not.15 Secondly, an optimal dose of energy must be deposited at the base of hair follicles. A good analogy would be treating an ailment with a specific dose of medicine: a precise number of milligrams, for instance, must be prescribed to a patient in order to address their problem effectively. In the case of LPT for hair loss, energy dosage is the amount of energy in joules (J) administered to a scalp area in centimetres squared (cm2) – thus is measured in J/cm2.16 Energy dosage is also called energy density or fluence, and is calculated by multiplying the power density of an LPT device by its treatment time. LPT is specifically governed by the Arndt-Schultz law, which dictates how much energy dosage should be administered during treatment (Figure 2). Therapeutic effects can be seen with a dose as low as 0.01 J/cm2; however, doses higher than 10 J/cm2 can inhibit repair and actually cause damage.17 In the case of LPT for hair loss, energy doses should range between 6-10 J/cm2 to achieve the adequate stimulation of hair follicles.
Another advantage of LPT is that it does not exclude the use of other common hair loss solutions such as minoxidil, finasteride and even newer, more experimental procedures such as platelet-rich plasma (PRP) injections. In fact, numerous patients choose to undergo LPT in combination with another treatment under the guidance of a hair loss expert or medical practitioner.
Additionally, hair transplantation patients can maximise the outcome of their surgery by integrating LPT in their treatment plan. Hair transplantation can come with several side effects – including infection, inflammation, scarring, facial oedema, swelling and the necrosis of transplanted grafts and surrounding hair.18 Some studies suggest that the practice of combining LPT with hair restoration surgery is rapidly expanding.19 Due to the release of nitric oxide and an increase of blood flow to hair follicles, LPT can produce stronger grafts before a procedure and reduce the extent of subsequent hair necrosis. LPT can also decrease swelling, redness and inflammation after a hair transplant.20,21 Thus the use of a convenient, effective, at-home LPT device is recommended for patients planning to undergo hair restoration surgery.
The anti-inflammatory properties of LPT and its proven abilities to augment hair shaft diameter, decrease vellus hair count and increase terminal hair count make it a very promising viable option for treating hair loss due to other causes, such as scalp conditions and various types of alopecia other than androgenetic alopecia. Many alopecia areata patients, for instance, have undergone LPT to treat their condition and have reported significant improvement.
Theories suggest that LPT could be efficacious at treating alopecia areata by stimulating hair growth in bald patches typical of the autoimmune condition.22 For instance, a study conducted in 200623 suggests that resistant patches of alopecia areata could be effectively treated at a high success rate with 904 nm pulsed laser light. Since LPT promotes hair regrowth in most hair loss patients,5,24 treating chemotherapy-induced alopecia with LPT is also promising; added to this is an encouraging animal study that reports superior and accelerated hair regrowth in rats given chemotherapy agents while undergoing LPT.25
By optimising the natural hair growth cycle and strengthening hair follicles, LPT has the potential to reverse or prevent traction alopecia. This type of alopecia is becoming a large concern amongst women who wear hair extensions26 and engage in potentially destructive hairstyling habits such as tight braiding or hair weaving.27
The future of LPT is indeed very promising. Today, convenient, affordable clinic and at-home LPT devices are available to individuals wishing to boost their current hair loss therapy or opt for an effective, alternative solution to topical hair loss lotions and medications. With further clinical studies, it should only be a matter of time before LPT is recognised as a standard form of treatment for many types of alopecia.
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