Hi, thanks for the query; you are diagnosed with bipolar 1 which means you have had at least one episode of Mania & 1 or more episodes of depression. Simple answer is NO;
lamotrigine (Lamictal) dosent cause cognitive deterioration. It causes dizziness, drowsiness, headache, blurred/
double vision, loss of coordination, shaking (tremor), nausea, vomiting, or upset stomach with occasional worsening of depression & suicidal thoughts. Considering your symptom profile, you are most probably suffering from an episode of bipolar depression. Hence you need to Consult your GP/
Psychiatrist for a detailed evaluation to ascertain its depression; followed by switch to either Lithium,
Quetiapine, combination of Olanzapine+
Fluoxetine which are better drugs than lamotrigine in their own right as mood stabilizers. Lastly start doing 30 minutes daily physical exercise, try to sleep for at least 6-7 hours each night; stay away from alcohol & other illicit drugs. If required, get back to me for further assistance. Hope this helps; good luck