Archive for the ‘Clinical Psychology’ Category
Heterotypic Continuity & Comorbidity
Heterotypical continuity means that an underlying (developmental) process or impairment stays the same, but the manifestations do not stay the same. For example a child with autism might first show impairments of non-verbal skills and problems in eye-contact. In a later developmental stage the manifestations would be different, such as stereotypical behaviour or language problems.
In psychopathological progression one disorder can be seen as a risk factor for developing another disorder. For example eating disorders such as anorexia nervosa have a influence on neurotransmitter levels such as serotonin. Imbalance of that neurotransmitter is related to general anxiety disorder and depression. In that way eating disorder do not cause depression, but it certainly puts the individual at a higher risk.
Whereas comorbidity is a correlational construct, the concepts of heterotypic continuity and psychopathological progression are causal theories in a developmental framework, that take the development of the individual into account. One could argue that, where comorbidity uses data to state a fact, the other two concepts actually try to explain the process.
Homeotypic continuity can be seen as the opposite of heterotypic continuity. Whereas in heterotypic continuity the process stays the same and the manifestations change, in homeotypic continuity the manifestations stay the same, but the underlying process changes. For example a child might resort to aggression, because it lacks the necessary skills to make contact with peers at schools. Later in life aggression against peers might be mainly attributed to an antisocial personal disorder.
The descriptive approach of the DSM – why clinicians love it – and don’t adhere to it anyway
In medicine, diseases are classified according to the physiological problem that is presumed to have caused the disease. Classification is guided by advanced biological and chemical theories that have proven to have explanatory value. For mental illnesses that is a different story, because the working mechanism is mostly unknown and there is no unified scientific framework that can explain the abnormal processes. Mental health professionals for different schools might explain any given symptom according to a different theory. In that light the DSM was created to be purely atheoretical and give a minimal framework on which everyone involved could agree upon. The resulting manual has helped communication about mental illnesses and has fostered comparable research in the field of mental health. However it is questionable if the structure of the DSM is compatible with the reality of humans, who (for the most) are driven by the unstoppable urge to make sense of their environment. Indeed it was found in many studies that therapists often classify without adhering to the specific rules laid out by the DSM. They are guided by internal rules, that work in a different way than the DSM checklist. For example therapists regard some symptoms as more important for a specific diagnose than others (concept of centrality). The DSM on the other hand usually assigns equal weights to all factors. Because the concept of centrality has profound influence on memory and other cognitive processes the therapist’s personal theory plays an important role in the classification. I believe that the DSM should be regarded as a tool supporting communication that allows discussion about the different theories at hand. It can and will not replace the theories people have. If a theory based classification system is available (for a specific disease) it should be used next to or instead of the DSM.
Non-verbal Behavior at Age 2 is significantly related to Language, Communication, and Social Outcome at Age 7
Charman et al. (2005) found that non-verbal behaviour was relatively robust and reliable on the different measurements over time, whereas the other indicators where not so reliable. In that light non-verbal behaviour might be a good indicator for the development of language and communication skills specifically and quality and frequency of social interactions in general (in the long run [heterotypical development]). Non-verbal behaviour might also be an indicator of the intrinsic motivation to learn socially. That motivation might explain why non-verbal behaviour at age 2 predicted later language, communication and social skills. This is also a good example how developmental psychopathology can increase the knowledge about the processes involved in the development of a disease.
Behavioural Science Blog 