According to ICH requirements, who should sign the written informed consent form in case of subjects with cognitive impairments?

In situations involving individuals with cognitive impairments, the ICH guidelines stipulate that the written informed consent form should be signed by both the subject and a legally acceptable representative, if available. This dual-signature requirement emphasizes the importance of ensuring that the rights and welfare of individuals who may not fully understand the implications of their participation in research are protected.

The subject’s signature signifies their agreement to participate to the extent they are able, while the legally acceptable representative's signature serves to provide additional legal and ethical oversight, affirming that the decision to involve the subject in the study is made in their best interests. This approach promotes respect for the autonomy of the subject, even if limited, and ensures that informed consent is appropriately obtained in accordance with ethical standards.

In contrast, the other choices do not align with ICH guidance for protecting the rights of vulnerable populations. Only having the legally acceptable representative sign disregards the subject's participation experience. Relying solely on the investigator’s signature fails to include the requisite consent from the participant or representative. Lastly, stating that no signatures are required undermines the foundation of informed consent necessary for ethical research practices.