54 year old woman with memory loss

A 54 year old woman came into my office a month ago for a Lyme evaluation. She had a history of tick bite/rash which had been treated with standard therapy three years ago. This history alone raised my antennae to the possibility of chronic Lyme. Her chief complaint was memory loss. She had no other symptoms typically seen in chronic Lyme patients. She described word retrieval difficulties, inattentiveness, brain fog and mild forgetfullnes. These are the typical symptoms described by many Lyme patients. Her neurological exam showed borderline findings, nothing concrete. Nonetheles, the history was compelling and I prescribed a one month course of Doxycycline pending the results of the diagnostic work up. After one month of therapy no Herx reaction or change in symptoms was noted. Her workup was unusually negative. The brain MRI and SPECT scan were normal. A standard Lyme laboratory profile was negative. A Clongen Western blot showed reactivity only at the 41band- both IgM and IgG. Does this patient have Lyme disease?

It seemed that the answer may be no. After contemplation, I decided to give her a diagnostic challenge. I prescribed Amoxicillin 7.5 grams per day, Biaxin 1 gram per day and Flagyl 1 gm per day for up to 15 days. I asked her to return in two weeks to have the Western Blot redone and to have a blood PCR for Lyme drawn. In addition, I told her that she should come in sooner for these tests if/when she has a significant Herxheimer response. I informed her that if the results were still negative and she did not Herx, I would not be able to establish the Lyme diagnosis.

If not Lyme, what is causing the memory issues? Many patients complain of cognitive changes. These were obviously significant enough to lead patients to seek medical attention. A family history of Alzheimer's disease or dementia is frequently reported, obvious causing greater concern to the patients. It is known that early, mild symptoms, over a period of years, can be traced back in patients who develop Alzheimer's disease.

Psychometric evaluations are expensive and probably of little value. They are only helpful if you have a "premorbid"(before illness) baseline. There is a great deal of variability under the bell shaped curve which could still fall into the normal range. High functioning individuals can easily loose 30-40 IQ points and still score normal on the tests. These tests are expensive and generally not covered by insurance. An evaluation by a neurologist will be unhelpful.
The only useful clinical parameter is the patient's description of symptoms.

No- it is not menopause. Many women I see are convinced that it is normal to experience significant cognitive decline after menopause. This is not true.

Are there other treatable causes? Perhaps not. A survey for other infectious diseases may be worthwile. It is possible that bacteria such as Chlamydia species, Mycoplasma species and viruses such as HHV6 may be playing a role. Alzheimer's disease is characterized as a progressive neurodegenerative disorder of unknown cause. It is known to be associated with inflammation and immune system activation.
If Lyme can cause cognitive dysfunction then it makes sense to consider the possibility of other chronic infections can act in the same way. At this point there is no treatment which can prevent Alzheimer's disease or modify its course. Some drugs are being investigated, including Namenda. Widening the paradigm which stems from experience with Lyme disease, could be applied in such cases, as long as patients understand that this is an experimental approach.

I have ommited the point regarding arguments that can be made with regard to an isolated 41band. However, without other typical Lyme feature, making this connection might be skating on very thin ice.