NGF may sound intriguing, but the price is a dealbreaker: at suggested doses of 1-100μg (NGF dosing in humans for benefits is, shall we say, not an exact science), and a cost from sketchy suppliers of $1210/100μg/$470/500μg/$750/1000μg/$1000/1000μg/$1030/1000μg/$235/20μg. (Levi-Montalcini was presumably able to divert some of her lab’s production.) A year’s supply then would be comically expensive: at the lowest doses of 1-10μg using the cheapest sellers (for something one is dumping into one’s eyes?), it could cost anywhere up to $10,000.
Taking the tryptophan is fairly difficult. The powder as supplied by Bulk Nutrition is extraordinarily dry and fine; it seems to be positively hydrophobic. The first time I tried to swallow a teaspoon, I nearly coughed it out - the power had seemed to explode in my mouth and go down my lungs. Thenceforth I made sure to have a mouth of water first. After a while, I took a different tack: I mixed in as much Hericium as would fit in the container. The mushroom powder is wetter and chunkier than the tryptophan, and seems to reduce the problem. Combining the mix with chunks of melatonin inside a pill works even better.
The one indisputable finding from the literature so far is that many people are seeking cognitive enhancement. Beyond that, the literature yields only partial and tentative answers to the questions just raised. Given the potential impact of cognitive enhancement on society, more research is needed. For research on the epidemiology of cognitive enhancement, studies focused on the cognitive-enhancement practices and experiences of students and nonstudent workers are needed. For research on the cognitive effects of prescription stimulants, larger samples are needed. Only with substantially larger samples will it be possible to assess small but potentially important benefits, as well as risks, and to distinguish individual differences in drug response. Large samples would also be required to compare these effects to the cognitive effects of improved sleep, exercise, nutrition, and stress management. To include more ecologically valid measures of cognition in academic and work environments would in addition require the equivalent of a large clinical trial.
The use of prescription stimulants is especially prevalent among students. Surveys suggest that 0.7–4.5% of German students have used cognitive enhancers in their lifetimes. Stimulants such as dimethylamylamine and methylphenidate are used on college campuses and by younger groups. Based upon studies of self-reported illicit stimulant use, 5–35% of college students use diverted ADHD stimulants, which are primarily used for enhancement of academic performance rather than as recreational drugs. Several factors positively and negatively influence an individual's willingness to use a drug for the purpose of enhancing cognitive performance. Among them are personal characteristics, drug characteristics, and characteristics of the social context.