4. Conclusion

Despite the fact that we can find some recent research, some of the articles are from the late 70s and 90s. For this reason, dated studies also affect the concept and model of bereavement. In the few studies where the conceptual framework is defined, this is based on the popular model of Kubler-Ross stages [41]. Today, different limitations of models based on stages are well known. At the methodological level, in many of the presented studies, there is a comprehensive and detailed description of both the sample and the procedure or statistical analysis. In this sense, it is worth noting that there are few studies that consider the relationship between these two constructs: SUD and bereavement. On the other hand, it should also be pointed out that in some cases they are evident and that some studies present some problems of scientific rigor and validity. Due to the characteristics of SUD patients, it is difficult to collect data, so some studies presented small size of the samples. As Hilgard and Newman [22] pointed out, some studies were characterized by poorly defined and incomplete

In relation to the assessment of different variables, the psychometric tests assess the psychopathology, personality, alcohol and drug use or dependence, self-esteem, social support, coping strategies, trauma-life history, and paternal bonding, but in general there is a lack of information about the measurement of bereavement. Few studies have measured the symptoms of complicated grief, except Masferrer's research [42], in which 34.2% of SUD patients reported

Another technique used which can cause a bias is retrospective call, as Hilgard and Newman [22] described. This outlines the different hazards involved in using old hospital records to derive statistical information and also the retrospective call depends on participants' memo-

Another important aspect to note is that, as Gregory [40] summarized, it is very common for the control groups to have been casual (medical students, hospital orderlies, not equated for age, sociodemographic factors that could be important). In most of the cases, the main characteristics of the sample are defined by two categories: (a) patients, which means that the person is attending a treatment and (b) participants, people who are not attending any treatment. This categorization may not identify addiction cases. They are not receiving treatment and may be

Locations of the vast majority of the studies cited were in the U.S.A. Six research studies were from Europe. Only one study was from Japan and two from Australia. This point is closely related to cultural variables that can be involved, both in relation to consumption and loss.

In many of the studies presented, a deterministic vision could be obtained, in the sense that a linear and direct relationship between loss and addiction were described. Therefore, it is essential to be cautious with the interpretation of the outcomes. It should be remembered that an SUD diagnosis is much more complex, complicated, multifactorial, and even dynamic than simple cause–effect relationships. In this regard, the studies do not consider other etiologic factors involved in addiction, so it is relevant to take into account the limitations from a reductionist point of view. From a psychodynamic approach, addiction is understood as a

included in a control group if this variable is not controlled in some way.

samples.

42 Drug Addiction

symptomatology of CG.

ries, which could be different from reality.

More transcultural research on this topic is needed.

This review presents different research studies which show the relationship between stressful life events and addiction over a wide range of years of publication. The majority of the revised quantitative studies support the hypothesis that there is evidence of a relationship between bereavement and addiction. According to Rugani etal. [31], the addiction might be affected by traumatic life events but it also has an impact on their development. Highlighting the possible relationship between the loss and the SUD could help to build a theoretical background. At a therapeutic level, it would be useful to take into account the bereavement of a significant person to improve the dishabituation treatment. However, a few of the studies [21, 34, 36–37] showed no relation between these two constructs. More research is needed to support and describe the bereavement phenomenon related to the addiction framework to support the inclusion of grief psychotherapy for those patients at risk of developing CG symptoms in addiction treatments.

Considering the studies shown, we can conclude that loss could have a role in the process of addiction. Because loss can have different influences on the pattern of drug consumption (precipitating the initiation of consumption, intake remaining unaltered, increasing or decreasing), it is important to be cautious. Loss could be a factor but more research is needed to clarify what kind of factor it is [26].

It would be significant to be able to understand the specific interplay of bereavement in the patient's personal situation and hopefully be able to develop even more effective and personalized treatment for each specific personal situation [44].
