Tuesday, December 16, 2014

Quetiapine for borderline personality -- journal article review

This is the first in a planned series of posts to summarize a few interesting articles from psychiatry journals published in 2014.

We begin with an article by Donald Black et al.from The American Journal of Psychiatry 171:1174-82.

It's a very simple 8-week randomized controlled study of treating borderline personality patients with either quetiapine XR 150 mg daily, quetiapine XR 300 mg daily, or placebo.  There were about 100 participants in all.   DSM-IV criteria were used for the diagnosis, and the participants could not have active substance abuse, or be in the midst of a major mood or anxiety episode, etc. 

The "Zanarini scale" was used to track symptom changes.  As I look up this scale, I find it appears to be a simple distillation of DSM-IV criteria, with raters giving each item a numerical score.   Unbelievably, I find that I cannot actually look at the questions directly (a fee of over $40 is requested!), which is quite surprising for what amounts to a small collection of very simple questions.

Nevertheless, the quetiapine groups did better than the placebo group on the borderline symptom scales.  But they did not do compellingly better on broader scales including the Sheehan Disability Scale or the GAF.    There was no advantage of the 300 mg dose over the 150 mg dose.

A few criticisms:

 1) I see the placebo group actually had lower baseline symptom scores, which could have biased the placebo group to show less improvement (e.g. through regression to the mean contributing to the larger symptom changes in the other two groups).     The fact that the graph given in the article showed only symptom change, rather than total symptom score, would have further hidden this bias from the reader.  The error bars were not shown in the graph of symptom change.   I see that the total symptom scores are not shown anywhere in the paper! I'm surprised this got past peer review in a major journal!


2) While 150 mg is considered "low dose" here, it would be useful to see what the effect of 25 mg or 50 mg would be. 

3)  As usual with studies of this sort, it is only 8 weeks in duration.  I would be interested in seeing a duration of at least a year.  This would be relevant not only for evaluating effectiveness (including symptom improvements and dropout rates), but also for evaluating side-effect risks (such as weight gain and metabolic changes).

4) The question is not addressed as to whether the more expensive quetiapine XR preparation is actually needed, compared to the less expensive regular quetiapine.  


In summary, a simple, mediocre study, which lends modest support for a practice that most practitioners probably already have done for years anyway -- which is to offer borderline patients treatment with low-dose atypical antipsychotic medications.




Wednesday, August 20, 2014

The Better Angels of Our Nature: Why Violence Has Declined, by Steven Pinker: A Book Review, Part 3

So, in conclusion, Pinker's book is very important and can be broadly applied not only to understanding and working towards continued reductions in violence, but these ideas can be useful in developing healthier psychological strategies in daily life.

These principles include:

1) continued education, to bolster reason, cross-cultural understanding, communication skills, empathy, historical knowledge, and even economics and statistics (these latter subjects can help combat cognitive biases which impede clear understanding of information pertaining to daily living)

2) foster trade instead of fostering war.  In some recent news examples, this may not be reasonable (e.g. with some extremely violent groups), but at the very least, fostering trade with adjacent communities would be useful to form alliances. 

3) exercise and strive for freedom of speech

4) expand our circles of empathy, to include those in other groups, cultures, and situations.  Ultimately, a global issue is to include the environment itself in our circle of empathy.  In depressive states, one may be directing aggressive thoughts or actions towards oneself.  So the circle of empathy should deliberately also focus on including oneself.

5) be aware of cognitive biases, such as overconfidence in the setting of conflict, underestimation of the risks of conflict, the tendency to deliver vengeful retaliations that would be considered excessive by a neutral observer, and to overestimate the malevolence of an opponent's motives.    This could be applied to an analysis about one's own depressive thoughts about oneself.

6) avail oneself of mediators or peacekeepers (this can be a role of a therapist).

7) move away from authoritarian or tribalist practices or beliefs, and instead focus on inclusiveness, individual rights, and fairness.  For those involved in religion, work toward a more inclusive, peacemaking, ecumenical, humble theology, with room to include modern scientific findings pertinent to morality, fairness, cultural understanding, and justice. 

8) strive for dignity rather than honour

9) work on ways to improve self-control.  This does not mean a renunciation of Dionysian enjoyments, but rather it means never allowing one's impulses or habits or enjoyments to cause harm or to rule one's life.




The Better Angels of Our Nature: Why Violence Has Declined, by Steven Pinker: A Book Review, Part 2

The first section of Pinker's book is an exhaustive review of violence rates throughout history.  This even includes looking beyond our own species, to other great apes, to understand aggression in our evolutionary lineage.  He also reviews cultural attitudes towards violence throughout the ages, as manifest in literature and the arts, and also in accounts of daily social and entertainment practices.  It is very disconcerting to learn about the extent to which horrifying acts of cruelty were commonly accepted, or even considered amusements (the events in the Roman Colosseum comprise just one of many, many examples)

Clearly, rates of violence were much, much higher in all previous periods of history.  Today the risk of suffering a violent non-suicidal death (from war or other crimes) is in the order of 1% or less (this is the total risk over an entire lifespan).    In most prosperous areas of the world it is much less than 1%.  Of the 245 000 deaths in Canada in 2012, 543 were due to homicide (0.2 % of the total).link   link2

But in all previous eras of human and pre-human history, these risks were orders of magnitude higher,  according to a variety of streams of evidence which Pinker amasses.  Instead of 0.2%, the rates were 10% or more.    If anything, much of this data may actually underestimate these past rates, since violence was so much a norm in previous periods of history that many violent deaths or even massacres were barely mentioned in historical texts.  Risks of non-homicidal violence were much higher still, such that most everyone in the population would have been traumatized in some way, or would have had a close friend or family member who was severely traumatized. 

Pinker outlines various of the forces which have driven violent behaviour over the ages; here are some of them:

1) predation
2) dominance
3) revenge
4) communalism/tribalism/nationalism
5) sadism
6) isolation
7) authoritarianism
8) ideology
9) lack of intelligence

1)
Predation is described as a simple goal-oriented motive, such as robbery or looting.  Yet this strategy is "zero sum" or "negative sum" in that there is no net gain during a robbery, only a transfer of property, and most likely a destruction of the means to efficiently produce more property (e.g. jewelry may be stolen in an attack, but the infrastructure or morale needed to produce more or better jewelry gets damaged in the process).

With societal evolution, free trade becomes a non-violent alternative to predation, which allows the process to be "positive sum."   In this case, goods could be traded for jewelry, leading to a prospering group of jewelers who can then produce more or better jewelry in the future.  Both parties gain.   In order for free trade to occur, and the ensuing reduction in predatory violence, there must be improved communication, a fairly governed commercial system, and penalties for predation which are agreed upon by both parties.

In a psychotherapeutic milieu, this principle could lead to the idea of improving communication and stable transactional rules between potentially conflicted individuals.  In general, the idea of trading with your enemy instead of fighting your enemy may not naturally occur to people.

Pinker does not adequately discuss some of the problems with trading relationships, and of free-market economics in general.  Such relationships can be imbalanced, exploitative on some level (either directly towards the individuals or nations involved, or towards the environment), or favouring a relatively small elite while having little benefit for the majority.  I think there needs to be more emphasis on "fair" trade, including a strong focus on environmental issues.  This is consistent with Pinker's observations about the need to expand a "circle of empathy."  This circle should expand to include not just trading partners, but the larger communities affected by trade, and the benefits or consequences to the natural environment.  Trade may often benefit the environment, through a simple economic efficiency argument:  the lowest-cost economic solution to a problem is favoured by free trade, which in turn can maximize the available eonomic resources to protect the environment.  But in order for this efficiency to be protective, there needs to be structured safeguards in place to prevent social or environmental exploitation. Another big issue I have found with conventional economic theory is that costs are underestimated (such as long-term environmental damage), and the cross-sectional cost appears to be very low; often those involved are not held responsible for the ultimate long-term costs.  In any case, this inaccuracy in measuring costs distorts the system, and causes it to be short-sighted.  

2)
Dominance contests can be seen in many species, often as part of a competition for mates.  Most often, of course, these are behaviours seen in males.  In humans, this can give rises to meaningless displays of strength or machismo, with an associated culture of "honour" in which small perceived slights can result in excessive aggressive reactions. Associated psychological phenomena include overconfidence, underestimation of the losses associated with the conflict, and of course lack of empathy for the opponent. In celebrating a culture of "glory and honour" there can be an utter disregard for the individuals and families affected by the ensuing violent losses.

If this type of behaviour is selected for in the population, it gives rise to large, aggressive, arrogant, reckless males who are easily provoked.  In other species it can give rise to males having harems with multiple mates, while driving away or killing other male challengers  (we see literal examples of this in human groups throughout history). 

In humans, this type of dynamic can occur in "honour-based" cultures; previous periods of history often featured distinguished gentlemen absurdly fighting to the death in duels, often over trivial conflicts.  But entire nations can behave in this fashion as well.

Improvement in this type of problem comes with greater education, strong emphasis on women's rights and gender equality, and selection pressure:  reckless, aggressive males with poor impulse control are much less likely to be found attractive as mates in the modern era!   Instead, most elements of modern culture favour self-control and a culture of "dignity."  It is no longer cool or attractive to be a bully or a hothead. 

3)
Revenge is an understandable reflexive process, and it is pointed out that some degree of revenge can be a deterrent to subsequent violence (to show no revenge can invite subsequent exploitation).  The problem with revenge, as Pinker shows, is twofold:  first, wronged individuals or states tend to want to deliver more punitive harm than a neutral mediator would prescribe.  The individuals doing the wrong likewise tend to underestimate their culpability or guilt (e.g. a great many convicted felons may have a smaller estimation of the magnitude of their guilt or responsibility for harm than a neutral observer or their victims would conclude).  This leads to a cycle of revenge, in which each group retaliates vindictively against each other, with force that is often out of proportion to the offense, and each wrongdoer underestimates their culpability.   The retaliation is itself therefore felt as an assault by the recipient, rather than as a fair punishment.  The violence therefore continues in an escalating fashion, with each group feeling justified in their actions, egregiously wronged by the other, and with each group inducing future acts of vengeance from their enemies.

The solutions to this predicament include having neutral arbiters--a fair system of policing and justice, empowered by a neutral and fair government which has a motive of minimizing overall harm in its citizens.

On a psychological level, a solution is to recognize the cognitive biases which lead to excessive retaliations and excessive justifications for one's own excesses.  Another solution is to recognize the need for neutral mediation to help resolve ongoing conflicts.

4)
Communalism, tribalism, or nationalism are understandable, common human experiences.  Early human culture required a cohesive sense of protecting one's fellow villagers from attacks from neighbours.  Yet, tribalism fosters patterns of revenge, predation, and dominance-based aggression on a group level.  Having separate tribal cultures, often with language and geographic barriers, is a barrier to empathy for outsiders, particularly if a cycle of warfare has already begun.  We see this type of aggression on a large and small scale, all around us.  In some cases it is playful, as in sports teams from different communities.  Gang behaviour in large cities has a tribal quality, with battles over control, protection, predation of resources, and "honour."   But entire nations behave this way.  We subjectively have an urge to enjoy national identity, but we have to be wary of the violent associations of this mindset.

An approach to this issue is to expand our "circle of empathy," and to view those from other groups as partners rather than enemies.   I suspect the healthiest vestige of nationalism that we can safely keep is to have sports teams.  I think this is also a reason to support free, fair international trade.  Protectionist policies must be based on a notion that there is an "us" and a "them".  But it is fair to view everyone in the world as part of "us" at this point.

Nationalist conflict is one of the most devastating factors causing worldwide violent death and suffering through the ages.

It is for this reason that I support the idea of having international sports events -- I believe that this is a symbolic peaceful sublimation of nationalistic conflict, transforming this type of tension into a playful harmless talent show.   The economic indulgence of such events, such as the Olympics, is an understandable complaint, but I think the pursuit of such playful, peaceful activities is very important.

5)
Sadism  may seem like a rarity, relevant only to extreme cases.  But smaller forms of this issue can occur in communities or in one's inner life.  The driving force in sadism is addictive:  repeated behaviours, even if extremely harmful, can lose their aversive or "taboo" character through repetition, and even lead to addictive pleasure, associated with excitement, relief of tension, etc.  This phenomenon can occur in personalities which had previously been quite "normal."    Pinker does point out the likelihood that psychopathic personality--a pathological lack of sympathy for others-- is a risk factor for sadistic behaviour, and that those with this type of personality are more likely to be attracted to occupations in which they could indulge their violent predilections.  In the book, he does not address the environmental or social causes of psychopathy, though alludes to this problem being at least to some degree a neurobiological variant with heritable aspects, and not entirely due to environmental adversity.  In any case, not all psychopaths end up becoming violent sadists, and not all sadists are psychopaths. 

 In depressive states, various forms of physical and figurative self-injury can become sources of relief, and lead to an escalating pattern of violence against self.   This is not "sadism" but it could be considered as arising similarly, as an addictive habit to which the person becomes tolerant and desensitized, leading to a craving for more and more highly destructive behaviour. 

A solution to this issue is to focus on prevention, and to recognize and avoid risk factors.  In a police or military setting, for example, it needs to be recognized that maltreatment of hostile prisoners can occur and escalate through this process.  Abuses of this kind are not some kind of bizarre perversion, but stem from failure to include judicial safeguards adequately to prevent the police or prison guards from getting involved in an addictive habit of maltreating others.  This can be challenging, because many of the prisoners may have behaved in a terrible way themselves (e.g. violent criminals) and so the initial aggressive responses to them may be approved by everyone involved.

In a personal setting, prevention is also important.  Self-injury often begins secretively, without the addictive risks being appreciated, and by the time the problem surfaces to others, it has become an entrenched habit.  At this stage, approaching it as a potentially lifelong addictive risk becomes necessary, with a variety of psychotherapeutic strategies employed.  For those who engage in sadistic behaviour towards others, I think society should be equipped to approach them as permanent risks to others' safety.   This does not necessarily mean longer prison terms, etc. (though this may be necessary in some instances) but I think it does at least mean longer-term societal scrutiny for protection of others.  

6)
Isolation is a risk factor for violence due to a tendency to form a stronger ingroup, view outsiders as a threat, lack the communication or language to resolve disputes peacefully with outsiders, and to lack the advanced education that could bolster diplomacy, empathy, or self-control.

During early human history, groups existed in relative isolation from each other.  Today, groups which are more geographically isolated (e.g. in remote mountainous areas) tend to have much higher rates of violence, as well as less education.  With the advent of modern communication and transportation technology, isolation on this level does not ever have to be as absolute as it has been in the past.  Yet, some groups may deliberately foster isolation, even when they live in large cities.  I think it is important to foster widespread community interactions between isolated groups.  

On a personal level, isolation is likely to magnify suspicion towards strangers, leading to exaggerated negative reactions to others' behaviour.

Psychologically, problems with isolation may be due to social anxiety, depression, or psychotic paraoia, but the isolation itself becomes part of the vicious cycle of symptom exacerbation.

Every person or community may have a certain "set point" for healthy engagement with others, e.g. some people are more comfortably gregarious than others, but I think some type of social practice and engagement is necessary for the health of individuals and communities. 

On a practical level, learning to speak other languages and customs lessens the isolative boundaries between people.  As a strategy of personal development, it could therefore be healthy to learn other languages, to travel to different countries, and to experience and learn respectfully about other cultures.  Treatment of underlying symptoms, such as paranoia or social phobia, can of course be important. 

7)
Authoritarianism evolves naturally from the most ancient origins:  stronger members of a group will dominate and assume leadership powers.  This factor fits closely with the ideological dynamics of aggression.  Those who challenge the authoritarian leadership can be subject to severe aggression.  One of the perpetuating factors for this dynamic includes the cognitive illusion that everyone supports the authoritarian leader or the authoritarian principles.  Even those who quietly dissent may be so fearful of reprisal that they will act to support the leader, and even punish other dissenters to prove it.  An analogous cognitive distortion is the belief among college students that the majority of their peers enjoy binge drinking--this belief normalizes such behaviour, and causes more people to engage in it because they erroneously thought it was an accepted norm.

A protection against this dynamic is fostering a politically open democracy with freedom of speech.  On a personal level, I think it is healthy and protective to question authority as an intellectual norm.  This includes not only teachers and professors, but also religious teachings.  Authoritarianism that is couched in religious dogma can seem so "sacred" that challenging it would seem disrespectful or like a taboo, thus leading to terrible unchecked excesses and distortions justifying violence or other harms and suppressing intellectual growth.

I had assumed that there would be a universal affirmation of the desirability of multi-party democracy throughout the world.  Yet, I have recently been looking at the PewResearch Global Attitudes Project surveys, including a poll done in 2009 (well before the recent conflicts in Russia and Ukraine).  (link)

This survey shows that people in Russia and several former Eastern-Bloc countries such as Hungary, have had a huge reduction in their enchantment with the idea of democratic government, beginning long before the recent conflicts.   Ukrainians gave some of the lowest ratings of all, regarding attitudes towards democracy, freedom of speech, etc.    I suspect that a major reason for this has been that the democratic changes in these countries have been laden with a lot of corruption, instability, and economic problems.

This is reminiscent of what Pinker described in post-colonial African states, which experienced a large surge in violence rates after declaring independence.  This does not at all mean that colonialism was "good," but rather that the benefits of democracy and societal freedom can only come after a state has become stable in terms of economy and political organization.   The period after major political upheavals can be relatively anarchic, and economically harsh, leading to a steep decline in morale for the population. 


8) 
Ideology can lead to extreme violence, through offering a cohesive set of beliefs which bind an ingroup harmoniously, often with a utopian goal, leading to a rationalization to destroy outgroups. Utopian goals can sound attractive, but often the enactment of these goals involve suspension of the other elements of societal growth and non-violence, such as fairness, justice, empathy for outgroup memebers, etc.  Those who commit catastrophic acts of violence within an ideological framework may understand their actions to be normal or just, and may easily dismiss complaints that their actions are wrong.     Our recent history is full of examples of this type, including Nazi Germany.

Unfortunately, there are many examples in history of religious ideologies leading to extreme violence in this way, continuing with examples in today's news.

A prevention for this type of problem includes education, including in the arts and humanities, a commitment to ecumenical approaches in theology (regardless of one's religious orientation), and a commitment to have diplomatic relationships with those having different ideological viewpoints.

I think these preventions apply on a large scale in societies, but also on a personal, individual level.

9)
Intelligence, the greatest talent of humankind, has the power to defuse conflict through negotiation, wise strategizing, and improved empathic understanding of one's opponents.    Cognitive biases are not eliminated by intelligence alone (as Kahneman has shown), but the capacity to employ reason rather than rage to solve problems is enhanced by intellectual training.  Such intelligence has grown over the generations, as Pinker has shown.  This is likely due to better education, and exposure to a more stimulating global cultural milieu.  Unfortunately, many in the world lack access to the basic resources or freedoms to develop their intellect in this way.  Part of global peacemaking must therefore include a strong emphasis on universal access to education.

Intelligence, of course, also permits a higher chance for employment, prosperity, and diverse leisure activities, all of which reduce risks for violence and other harms.

On a more immediate, personal level, intellectual development could be framed as a component of psychotherapy.  This could work not only as a way to focus the brain on activities apart from depressive rumination, but also could strengthen faculties of the mind which could act as skilled "negotiators" to calm the self-injurious impulses which can occur in depression or anxiety.  Some of the CBT literature shows that this type of therapy works better in those who are more highly educated.  Conversely, I suspect that better education and intellectual training can make psychotherapy work better.







Tuesday, August 19, 2014

The Better Angels of Our Nature: Why Violence Has Declined, by Steven Pinker: A Book Review, Part 1

I have just finished Steven Pinker's book, The Better Angels of Our Nature: Why Violence Has Declined

I think it is a masterpiece of scholarship and research, combining the fields of psychology, history, political science, anthropology, economics, and statistics to contribute a hopeful affirmation about the progress the world has made to reduce violence and to improve quality of life.

My favourite scholarship is the type which combines multiple fields in this way!  

In these posts I would like to briefly summarize the book, and to reflect about ways to apply some of Pinker's insights to the practice of psychotherapy.

I see there has been mostly strong praise for this book among critics, but predictably there has been some controversy.    Cultural groups which still have strong authoritarian, communal, tribal, sexist, or fundamentalist values may find some of Pinker's conclusions to be critical of their way of life.  Mind you, he does show that in almost all such subcultures, such as conservative groups in the U.S., there have been positive changes, for example towards affirming rights for previously disenfranchised groups.  It is just that these changes usually lag a decade or two behind such changes in the rest of the population.  An attitude about women's rights or gay rights that would have been called "liberal" in 1970 would be considered a norm in many conservative groups today. 

Pinker shows that most elements of religious belief and practice have had negative impacts on rates of violence and war, due in part to causing an ingroup mindset, which tends to undervalue the human worth of non-believers, therefore facilitating maltreatment of those with a different faith.    Also most religions have a type of authoritarian structure, including about the concept of divinity itself.  The notion of an afterlife can not only model infinite punishment ("hell") as a supposedly fair possibility for an individual based on offenses such as "disbelief" but could encourage such an attitude of infinite punishments in approaching other individuals or cultures.  Conversely, with infinite reward ("heaven") in the picture, perhaps with simple criteria such as "belief" to be the ticket of entry, this could be experienced as a license to engage in many destructive acts during life while minimizing the relative value of earthly justice.

Other critics question his statistics, but here I think he has been very impressively thorough.  His statistics do not at all imply that violence has miraculously disappeared in modernity, and very clearly do not imply that the most horrific possibilities of violence -- such as the scale of events which happened in World War II -- cannot happen again.  In fact, his discussion of statistical power-law distributions modeling violent conflict gives rise to great concern:  based on this distribution, one can expect an arbitrarily large and devastating conflict to occur in the future, since this type of distribution is "tail heavy" statistically.  His analysis does give reason to be hopeful, though--the underlying causations and probabilities which become the parameters of these statistical patterns are themselves declining.

An example of a power-law distribution is the length of words that would be generated on a typewriter if one were to type on the keys and the spacebar randomly.  Typing the spacebar would separate individual words.   The length of the word would represent the magnitude of  (or loss of life from) a violent conflict. With this analogy, a conflict happens every time the spacebar is pressed. One could see that short, small conflicts would be most common, but that longer, larger conflicts could happen periodically, though less frequently, in a random pattern.  It is disconcerting that this type of distribution can have an infinite expected value, representing total destruction of the population.  As we know, this is actually a possibility in the nuclear age.

But Pinker's thesis also shows that the parameters of this imaginary typewriter are changing--with time, the typewriter is gaining more and more keys (just like Microsoft keyboards!).  This causes the relative risk of pressing the spacebar to gradually decrease with time   Also, metaphorically, Pinker is showing that the information content of each key is increasing, so to speak, causing fewer keys to need to be pressed at all.    Just as with computer keyboards, we are even developing ways to interact without using keyboards at all (e.g. with mice, or voice commands).  The mechanisms he shows for these changes in risk parameters are increased education, intelligence, an expanding circle of empathy, an expanding force of reason, improved human rights (e.g. for women, racial minorities, and people having different sexual orientations), free and fair trade,  and improved stable government (what he calls the "leviathan").



Thursday, April 3, 2014

Deep Pressure Stimulation for anxiety, ADHD, insomnia, or autism


Someone was telling me last week about a snug sweater that is available for your pet dog or cat, which is intended to soothe anxiety or phobic behaviour!  Here is an informational site for a business selling this:  https://anxietywrap.com/about/pressure.aspx
The whole idea made me smile!   Maybe it’s gimmicky, but what if there’s something to this?

I think the idea is very simple, that pleasant, hug-like tactile stimuli can be emotionally comforting.  As with other sensory stimulus treatments for mental health symptoms, why not try tactile things?  We have, for example, bright light therapy, calming audio recordings, and aromatherapy, each of which have a reasonable evidence base.  Of course, there is massage therapy, but usually this would consist of  brief, fairly expensive sessions which would rarely be practical to arrange daily or continuously.  
Here are the results of my survey of this issue:
For children with autism or attention problems, there are weighted compression vests available on the market, which are supposed to help cognition, comfort, and behaviour.  These are simply vests which weigh about 10% of body weight:  http://funandfunction.com/weighted-compression-vest.html

 http://www.ncbi.nlm.nih.gov/pubmed/24581401   This 2014 study in an occupational therapy journal showed significant improvement in ADHD symptoms in 110 children, average age 9 years.  The study had a randomized, crossover design, with subjects putting on the vest and immediately doing a CPT test.  The subjects were scored according to the CPT test result, and according to observations of behaviour during the trial.   Symptom improvement attributable to the vest was quite significant: about 20% improvement in being on-task, 50% reduction in fidgeting, and 20% reduction in CPT omission errors. 

http://www.ncbi.nlm.nih.gov/pubmed/12959226  In this study, the 4 weighted vest subjects had 18-25 % improvement in on-task behaviour, also 3 of the 4 children asked to wear it more! 

http://www.ncbi.nlm.nih.gov/pubmed/18592366  In this review article, they found insufficient evidence to recommend weighted vests. But most of the studies reviewed were looking at very young children (under 5) with autism.  It is of greater interest to me to look at the use of this strategy for older children and adults with anxiety or attention problems. 

This study showed that swaddling babies reduces the pain response to a blood test needle, compared to control.  
Temple Grandin is a famous autistic woman, with a BA in psychology and a PhD in animal science, who has been very open about her personal history; she has become an authority in the area of providing safe, ethical care and comfort to agricultural animals.    These are links to Grandin’s 1992 paper in Journal of Child and Adolescent Psychopharmacology in which she describes her own very beneficial experience of a device she built (“the squeeze machine”) which she used daily for many years.
She found this machine to be comforting, and to even improve her subsequent ability to tolerate other types of sensory and interpersonal stimuli as an adult.

Here is a very recent article with Grandin as co-author: http://www.ncbi.nlm.nih.gov/pubmed/24419314  This is a case study of a woman with bipolar disorder who reported some benefit from deep pressure techniques.  Other adjuncts in this case were use of a squeeze ball, chewing gum, lightly tinted glasses, and a soft brush to rub against the skin. I'm a bit surprised this got published, though, since it seems they didn't really use any one technique systematically. 

Weighted blankets are another idea along these lines.  Here is a website selling items like this: http://www.hippohug.ca/   I see the weights are up to 20 pounds for a larger blanket, again with a recommendation of about 10% body weight.    It seems like a home-made version of this wouldn’t be too hard to make, or at least to experiment with.  The material used for the extra weight is often simply small, smooth stones.  
   
Sleeping in a mummy bag (a type of sleeping bag used for camping) is another similar idea.   

So, in summary, deep pressure stimuli of this sort could be worth a try to treat ADHD, anxiety, insomnia, or tactile hypersensitivity, with very little risk.  I suspect one could get an idea of results and tolerability quite quickly.  A key idea, that Grandin emphasizes, is that the stimulus should always be fully under your control, so it would be useful I think to be able to adjust the weight, and to remove it very easily.