Tricky relative clauses
The following attested example poses some interesting syntactic questions:
For instance, the past couple years have seen the development of two new treatments for Alzheimer’s (donanemab and lecanemab), which clinical trials indicate slow down the progression of the disease – and which have led to bold claims, by pharmaceutical companies such as Lilley, that this is the “beginning of the end” of Alzheimer’s. (Devi Sridhar, the Guardian 8 April 2025)
Here we see two relative clauses (in bold) which are linked by the coordinating conjunction and. Both are introduced by a relative pronoun, which functions as the Subject of each clause.
I’m interested in the first of these relative clauses. It becomes clear that the relative pronoun which functions as the Subject when for a moment we disregard the words clinical trials indicate. The relative clause then reads which slow down the progression of the disease.
But how do we deal with clinical trials indicate? If you read the sentence out loud, you’ll probably pronounce it with a lower pitch, perhaps preceded and followed by a very short pause.
What is this string of words doing here, and how do we deal with it syntactically? The lower pitch and pauses perhaps indicate that it is an insertion that is not fully syntactically integrated in the sentence. This is similar to the way in which interpret appositional structures, as in this example:
Mrs. Obama, the former President’s wife, visited our school.
Here the noun phrase the former President’s wife is in apposition to the NP Mrs. Obama, and is not syntactically integrated in the clause, witness the fact that when we read it out loud, it is pronounced with a lower pitch and pauses before and after.
I would argue that clinical trials indicate is a subordinate clause, without an overt marker of subordination, but if we did have a subordinating conjunction, it would be as:
which, as clinical trials indicate, slow down the progression of the disease
Now if this is correct, we have the verb indicate in this clause, which lacks an Object. However, although the Object is left unexpressed, we interpret the entire construction as follows:
For instance, the past couple years have seen the development of two new treatments for Alzheimer’s (donanemab and lecanemab). Clinical trials indicate [that these slow down the progression of the disease].
In this reformulation the Object of indicate is a that-clause: that these slow down the progression of the disease.
Unexpressed Objects are not uncommon. Have a look at the next (made up) similar example:
I love London, which you know is magnificent.
This seems to be a more economical way of expressing a number of separate propositions:
I love London. London is magnificent. You know this.
The compression works quite well here.
But let’s go back to the attested example at the start of this post. Do you prefer it to the rewritten version below?
For instance, the past couple years have seen the development of two new treatments for Alzheimer’s (donanemab and lecanemab). Clinical trials indicate that these slow down the progression of the disease, and they have led to bold claims, by pharmaceutical companies such as Lilley, that this is the “beginning of the end” of Alzheimer’s.
I have a slight preference for the rewritten version. What do you think? Leave a comment below.
I think that maybe 'clinical trials indicate' is indeed parenthetical (although I can say it either way, with or without parenthetical intonation). For me, that might be part of why I find the first version to be slightly more interesting and engaging. There are a few reasons why it's effective. Firstly it builds through three successively more interesting and more dramatic propositions. While doing this, the reader is always aware that there is more information coming in the sentence, and they are not disappointed by the finale, which is aptly more dramatic and interesting than the preceding clauses. So in some sense the reader is kept in suspense as the sentence develops. This sense of anticipation is aided by the parenthetical 'clinical trials indicate' in the first relative clause and the interpolated 'by pharmaceutical companies such as Lilley', in the second, which both serve to delay the arrival of the anticipated key information. This is reinforced by the fact that this effect is duplicated across the two relative clauses. For me, the delayed 'this is the “beginning of the end” of Alzheimer’s' in the first formulation is a fitting crescendo, a decisive and final flourish at the end of the sentence. This effect is missing, I feel, from the reformulation. Whether the second benefits more from the point of view of simplicity and clarity is, perhaps, a matter of opinion. However, I'd argue that in the first the writer gives a clear indication of the relative importance of the information in the three clauses, something missing from the second.
I like the rewritten version better, as well. I believe I used to write a lot in the style of the original Alzheimer's paragraph, and have lately been trying to compress my writing away from tricky relative clauses. This makes me wonder: do you believe relative clauses were very popular among writers of classic literature? Reading the original Alzheimer's paragraph gave me that "feel."