Fuzzy thinking or general lack of concentration can be a common symptom of menopause and also in perimenopause. The difficulty of being able to think straight is actually part of the onset of perimenopause as well as menopause, and women frequently complain of poor short-term memory and a loss of concentration at this time.
You will find that you may be forgetting things more frequently or not being able to focus on things that you have to do. You are experiencing a very different time in your life, especially in perimenopause where stress, irregular periods, hot flushes and other symptoms, such as mood swings etc., make you worry more about your memory and concentration problems. This can make a difficult time even more so.
Source: 34 Menopause Symptoms. 2017. 34 Menopause Symptoms. [ONLINE] Available at: https://www.34-menopause-symptoms.com/difficulty-concentrating.htm. [Accessed 10 October 2017].