Relationship Between Genetic and Biological Factors in Bipolar Disorder and Schizophrenia

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23rd Sep 2019 Psychology Reference this


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 Temperament dimensions in Psychopathology: Are the offspring of patients with the bipolar   and schizophrenia disorder, at risk of developing the psychotic phenotype


The focus of this piece of research, is to look indicating the relationship between genetic and biological factors of the bipolar disorder (BpO) and schizophrenia (SzO). Indicating to what extent do the offspring inherit these disorders from existing patients. Dfaz-Caneja et al., (2018) are clear when expressing current knowledge on this subject through reviewing appropriate literature. As a result of this, there is a notion that the children of patients with the existing disorders BpO and SzO, show more distinctive temperamental patterns with comparison to typically developing offspring.

There are assumptions and links expressed within this study to certain aspects of temperament, to a range of cognition skills. The idea that temperament is defined as being rooted from biological aspects of development. Rothbart and Bates (1998, cited in Zenter & Shiner, 2012) presumed that temperament, forming an individual’s personality, comes from strong genetic and neurobiological factors. However, Rothbart (2011) expressed that personality differences in children, were almost, always a result of environmental factors. This idea stemmed from aspects within social learning theories.

Nougera et al (2018) published an article which stresses similar concerns for the offspring of patients with schizophrenia. This research states the ‘high alert’, for the strong genetic component and how it can affect the offspring of patients diagnosed with this disorder. Again, this research compares this assumption with a control group which consists of non- schizophrenic parents. However, Dfaz-Caneja et al., (2018) acknowledged that no previous studies have conducted experiments to compare and assess specifically the temperamental dimensions in children with BpO, and the relationship with SzO. A limitation lies within the acknowledgement of the lack of research regarding temperament dimensions in SzO.

Nevertheless, this limitation is disregarded through the ability to highlight a gap and devise an appropriate hypothesis to broaden knowledge on the effect of Schizophrenia. A hypothesis, which claims the association of poorer adjustment and increased lifetime rates of psychopathology, will be shown through higher scores in specific temperament dimensions.  According to Trochim, Donnelly and Arora (2015) the statement of a specific direction is seen within a one tailed hypothesis. The hypothesis within this study uses the word ‘higher’, which indicates a specific direction and possibly a significant difference.


In order to test this hypothesis, Dfaz-Caneja et al., (2018) chose an age range for the offspring of 6- 17-year olds to take part within this study. Although using this age range may be an advantage as the offspring are more developed, there is also a limitation which lies with this. Levine and Munsch (2016) explained how past research states overtime, children have the tendency to maintain the same temperament. With that in mind, it is also argued that small changes may occur through development, causing some changes within an individual’s temperament. There is a suggestion of certain aspects of vulnerability changing overtime, the notion that individuals may exhibit more externalising traits within early childhood, (Munsch& Levine, 2016). Considering these arguments, a suggestion of using a wider age range for sampling, would help to determine whether specific temperament dimensions of both disorders, are present from birth.

This study was designed using a mixed method approach. Looking firstly at the main qualitative technique which may implicate results, such as direct observations. According to Coolican (2014) there are strengths and limitations of the use of direct/ naturalistic observations. Although Dfaz-Caneja et al., (2018) may have used this approach to examine each offspring in a naturalistic setting, to gain a more accurate insight to how that individual acts within a non-controlled environment. However, this may be a limitation when considering the possibility of certain behaviour being amplified, through the acknowledgement of being observed. Coolican (2014) states the occurrence of such limitations within past studies. Given this argument for the experimental conditions, this may have implicated small aspects of the data, due to certain temperament traits being expressed within observation, such as increased hyperactivity or visible augmented anxiety/shyness.

Looking solely again at the use of direct observation, there is no indication that any consent was given by the child nor the legal guardian. According to the British Psychological society (BPS) (2014) vulnerable populations, in this case children, should be given the opportunity to understand the nature of the study. As some individuals may not be capable of giving consent, it is the duty of the legal guardian to do so. However, throughout this study there is no indication that any consent was given when considering observation. Along with this ethical issue, there is also an assumption that if the child has become aware of being observed, it may cause that individual stress. Again, referring to the BPS code of ethics, the welfare of participant may be hindered if stressed.


Dfaz-Caneja et al, (2018), noted the presence of single- item missing values. The use of sub group mean imputation was to eliminate chances of any lost information which may be valuable to the study. According to Little (2013), it isn’t uncommon to see mean imputation within a cross- sectional study. Little (2013) states the inclusion of additional variables within imputation, to predict the missing data. When acknowledged, this could provide a strength for a study as this strategy provides a complete data set, (Enders, 2010). With that in mind, this particular study highlighted the inclusion of the missing values of two inpatient mothers. On the other hand, Enders (2010) emphasises that the use of mean imputation can result in reduced variability of data. This can reduce the value of the standard deviation.

Concluding thoughts from the results presented through statistical analysis, the direction of the experimental hypothesis was portrayed in the data. Dfaz-Caneja et al., (2018) expressed that the findings within the unadjusted analysis show ‘significant’ lower scores within the adaptability and positive mood aspects of the research. These scores were portrayed by the BpO and SzO subgroups in comparison to the community control offspring (CcO). Looking at table two (see appendix one) provided within this study, there are significant differences which are shown through the probability scores. The statistical figures of probability range from 0.001 to 0.007, in aspects within activity, adaptability and mood. These figures are all under the alpha level p= 0.05, and therefore, back up the findings in which the researchers state was found. Given these circumstances, it is clear how the researchers were able to accept the experimental hypothesis. There is a significant difference shown between the BpO and SzO offspring’s groups in relation to the CcO, and all differences are in the direction which was previously stated by the conducted hypothesis, (Coolican, 2014). A strength for any study.

However, there are limiting factors of the data shown. Although there are number of tables providing a range of data from different variables, all are not presented. Within table three (see appendix two) where the data from the logistic regression models are presented, the use of only the covariate variables are highlighted, which are of direct interest. There is a possibility that this strategy may have been used to predict outcomes from the continuous dependent variables. Giles (2002) states that ANOVA, which was used within this study, can detect a significant result using more than one covariate. This study validates this statement as all probability factors show levels below the alpha and therefore show significant results.


Throughout the study there is further reference to the results as being consistent to previous studies, results which show reduced positive mood within children and adolescents with BpO. Taking into consideration the argument on how genes can affect the likely hood of exhibiting the disorders BpO and SzO, there is now a question on more external factors which stress the influence of environmental aspects. This piece holds the the assumption that environmental stressors such as the parental strategies of parents with either disorder, may further influence possible development of certain temperament traits related to psychopathology.

With that in mind, an agreeable suggestion put forward by the researchers, would be to use longitudinal prospective designs within further research. This will help to test and detect vulnerable temperament dimensions in early development including social development. There is notion that using studies through a longer period can develop a better understanding and more expertise knowledge on the development of psychopathology, (Levine & Munsch, 2016).

The techniques used throughout holds validity and reliability which has been stressed through other conducted studies, like this. Dfaz-Caneja et al., (2018) stress that all results are to be considered and replicated with caution. This stems from the use of such a small and uneven sample. A suggestion of replicating the study with a much larger sample which represents the population at a wider scale. This suggestion also imbeds within the previous proposal of using a longitudinal study. This will allow further researchers to thoroughly test whether biological or environmental stressors are to blame.

Although the results show significant differences in certain temperament dimensions in each offspring group. There is a still a question of to what extent parents who exhibit the disorders, influence potential temperament traits in offspring. With this question in mind, it is clear when concluding the results, that the findings indicate a correlation which shows the influence of reduced positive mood and increased activity, as indicators of the development of the disorders BpO and SzO.

In conclusion, it is apparent that Dfaz-Caneja et al, (2018) were successful in providing data which backs up the original experimental hypothesis. However, further research will aid in developing a better understanding of the discussed relationships.


  • Coolican, H. (2014). Research methods and statistics in psychology (6th ed.). East Sussex: Psychology Press.
  • Enders, C.K. (2010). Applied missing data analysis. USA: The Guilford Press.
  • Giles, D.C. (2002). Advanced research methods in psychology. East Sussex: Routledge.
  • Little, T.D. (Ed.) (2013). The oxford handbook of quantitative methods in psychology (2nd ed.). USA: Oxford University Press.
  • Littell, R.C., Milliken, G.A., Stroup, W.W., Wolfinger, R.D., & Schabenberger, O. (2007). SAS for mixed models (2nd ed.). Cary, NC: SAS Institute INC.
  • Levine, L.E. & Munsch, J. (2016). Child development from infancy to adolescence. California: Sage Publications.
  • Noguera, A., Castro-Fornieles, J., Romero, S., Serna, E.D.L., Sugranyes, G., Sanchez-Gistau, V. … Baeza, I. (2018). Attenuated psychotic symptoms in children and adolescent offspring of patients with schizophrenia. Schizophrenia Research, 193, 354-358. doi: 10.1016/j.schres.2017.07.050.
  • Rothbart, M.K. (2011). Becoming who we are: Temperament and personality in development. New York: The Guildford Press.
  • The British Psychological Society. (2014). Code of Human Ethics. Retrieved from
  • Trochim, W.M., Donnelly, J.P., & Arora, K. (2015). Research methods: The essential base knowledge base (2nd ed.). Boston: MA: Cengage Learning.
  • Zenter, M. & Shiner, R.L. (Eds.) (2012). Handbook of temperament. New York: The Guildford Press.

Word Count 1574


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