The Pharmaceutical Journal
Vol 273 No 7309 p126
24 July 2004

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Dogs and vocabulary more
Passing the buck over child protection more
Cannabis may not present psychosocial risk to youngsters more

Dogs and vocabulary

In Science for 11 June is a fascinating account of experiments to discover how dogs as well as children can learn words that determine their activities. The researchers, a group of psychologists from Leipzig, comment that most human toddlers acquire a vocabulary at an astounding rate. From about the age of two years typical English-speaking children add about 10 words to their vocabulary every day, and by the time they graduate from high school possess an average vocabulary size of 60,000 words. It is not, however, understood whether the process of learning is unique to language acquisition or may reflect general cognitive ability that children share with other living creatures.

A domestic border collie’s ability to memorise labels of over 200 items, mostly children’s toys and balls, was assessed by studying his ability to retrieve them correctly on request. During training, the dog was asked to fetch objects from different locations in the home and rewarded with food or a romp when he fetched them correctly. The investigators arranged sets of 10 separate items with which he was familiar in a room and instructed the owner to request the dog to bring two randomly chosen items when told to do so. Of 40 items tested, 37 were correctly retrieved. Moreover, he could place the item in a box or bring it to a certain person on request. When novel objects were added, the dog could distinguish them from the familiar ones when requested to do so.

The experiments showed that the dog could associate the acoustic pattern of human words with specific environmental objects, and that he could memorise the association for at least four weeks. Whether this ability paralleled that of a child to identify an object by name remains to be determined. But it appears that “some of the perceptual and cognitive mechanisms that may mediate the comprehension of speech were already in place before early humans began to talk”.

It remains to be seen whether a dog is able to obey a negative instruction — not to do a thing — in the same way as a child can be forbidden to touch something.

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Passing the buck over child protection

To judge whether or not a child is in danger of being mistreated or has indeed been abused by a parent or relative is a tricky business. A number of recent cases in which suspicious deaths of young children have aroused considerable doubt over the circumstances responsible have demonstrated how carefully we have to tread when suspicions have been aroused and call for appropriate forensic reports and expert opinions.

The matter has been ventilated in an editorial in The Lancet for 26 June. Charges of irresponsible and unprofessional actions by paediatricians have been brought by the appropriate medical authorities, and the role of medical expert testimony and also that of legal experts has been questioned. It is impossible to know whether those paediatricians whose judgements have been prominent in the newspapers represent the general views of such experts as a whole. What doctors know about child abuse as a possible cause of death is not accurately ascertainable, and so their witness may be misleading. Those who are prepared to undertake child protection functions are becoming scarce because of the distrust now shown them by the public and the legal profession. A prognosis or treatment based on the opinion of one expert, unless supported by other evidence, is no longer acceptable in the situation today, however valid it was once judged.

Few doctors have any expertise in the law, and few lawyers keep abreast of advances in medicine. More training and communication is necessary in order for these distinct professions to interact safely. Doctors must be able to make information provided to a court of law sufficiently transparent, and at the same time lawyers must be able to assess what medical information means when presented as fact by a doctor. ‘‘Without appropriate intervention, lawyers will continue to dispute with one another, doctors will continue to hypothesise, and children will continue to be abused.” Fundamental reform is called for urgently.

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Cannabis may not present psychosocial risk to youngsters

The results of a wide-ranging examination of statistics relating to the possible psychosocial and antisocial effects of the abuse of cannabis by young people are reported in an article that appeared in The Lancet for 15 May, from doctors working in the universities of Birmingham, Keele, Bristol, London and Berne. Their findings indicate that there is no strong evidential support for a causal relationship between the use of cannabis and psychosocial harm, although the possibility of such a connection cannot be discounted.

It is known that the use of illicit drugs among young persons is widespread and possibly increasing. Cannabis is the most widely used, though psychostimulants are also quite common, but opiates less so. The use of cannabis is associated with problems of psychological health, recourse to other illicit drugs, reduced educational attainment and antisocial behaviour, though clear causal links are not established.

It is suggested that drug use and psychosocial harm could be linked through two principal mechanisms — directly through neurophysiological pathways or indirectly through involvement with the criminal culture and commerce associated with the use of illegal substances.

It was found that cannabis use was consistently associated with diminished educational attainment and recourse to other drugs. Its association with a person’s psychological problems was, however, inconsistent, as was that with antisocial or otherwise problematic behaviour patterns. When cannabis was used at a younger age the later problems were consistently greater.

Studies of associations between the use of cocaine or opiates and subsequent psychological symptoms showed mixed results, and evidence regarding amphetamines and methylenedioxymethamphetamine ( “ecstacy”) was inconclusive, although both seemed to be used widely.

It is suggested that psychosocial problems might be a cause rather than a consequence of cannabis use, since individuals with a prior tendency to experience psychological difficulties might also be particularly prone to drug use problems, especially those related to cannabis. There is no evidence that a growing use of cannabis use by youngsters in recent years has led to an increase in the incidence of schizophrenia.

Physical harm following drug habits may be serious with some drugs, but apparently not with cannabis, where intermittent use in adolescence to early adulthood may have minor effects but not serious ones. The evidence overall for cannabis having important consequences for later psychological or social health is not strong.

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