Which statement is true regarding the testing of the olfactory nerve?

The statement that abnormal responses may be seen in otherwise normal elderly individuals regarding the testing of the olfactory nerve is accurate. As people age, it is common for them to experience a decline in their sense of smell, known as presbyosmia. This can lead to diminished olfactory sensitivity or changes in smell perception even in the absence of any underlying pathological conditions. Therefore, an abnormal response during olfactory testing in elderly individuals may not necessarily indicate a neurological or severe issue, but rather a normal consequence of aging.

The other options do not hold true in the same way. For instance, unilateral testing of the olfactory nerve can provide important information about potential asymmetries in olfactory function, making it relevant to consider laterality. Additionally, while not every smell must be identified for a response to be considered normal, a baseline level of smell identification often is expected for a comprehensive assessment. Lastly, allergies can impact the sense of smell and thus can affect the outcomes of olfactory nerve testing, as they may cause nasal congestion or other factors that impair olfactory function.