28 It is axiomatic that prisoners should not be subject to a special security regime any longer than the risk they present makes necessary. This calls for regular reviews of placement decisions. Such reviews should always be based on the continuous assessment of the individual prisoner by staff specially trained to carry out such assessment. Moreover, prisoners should as far as possible be kept fully informed of the reasons for their placement and, if necessary, its renewal; this will inter alia enable them to make effective use of avenues for challenging that measure. Life-sentenced and other long-term prisoners 33. In many European countries the number of life-sentenced and other long-term prisoners is on the increase. During some of its visits, the CPT has found that the situation of such prisoners left much to be desired in terms of material conditions, activities and possibilities for human contact. Further, many such prisoners were subject to special restrictions likely to exacerbate the deleterious effects inherent in long-term imprisonment; examples of such restrictions are permanent separation from the rest of the prison population, handcuffing whenever the prisoner is taken out of his cell, prohibition of communication with other prisoners, and limited visit entitlements. The CPT can see no justification for indiscriminately applying restrictions to all prisoners subject to a specific type of sentence, without giving due consideration to the individual risk they may (or may not) present. Long-term imprisonment can have a number of desocialising effects upon inmates. In addition to becoming institutionalised, long-term prisoners may experience a range of psychological problems (including loss of self-esteem and impairment of social skills) and have a tendency to become increasingly detached from society; to which almost all of them will eventually return. In the view of the CPT, the regimes which are offered to prisoners serving long sentences should seek to compensate for these effects in a positive and proactive way. The prisoners concerned should have access to a wide range of purposeful activities of a varied nature (work, preferably with vocational value; education; sport; recreation/association). Moreover, they should be able to exercise a degree of choice over the manner in which their time is spent, thus fostering a sense of autonomy and personal responsibility. Additional steps should be taken to lend meaning to their period of imprisonment; in particular, the provision of individualised custody plans and appropriate psycho-social support are important elements in assisting such prisoners to come to terms with their period of incarceration and, when the time comes, to prepare for release. Further, the negative effects of institutionalisation upon prisoners serving long sentences will be less pronounced, and they will be better equipped for release, if they are able effectively to maintain contact with the outside world.