Symptom Guide

Memory Loss & Forgetfulness

Name: Memory Loss: Causes, Blood Tests & When to See a Doctor
Creator: Suman Konda
Published: 2026-07-05

Memory loss can be caused by treatable conditions like thyroid disease, B12 deficiency or depression: or may indicate dementia. Blood tests identify the reversible causes first.

Written by Suman Konda, PharmD, Clinical Pharmacist · Editorial policy · Not medical advice

Last updated: 01 August 2026 · How we check our content

Blood tests for memory loss

Test	Why ordered	Treatable if abnormal?
TSH	Hypothyroidism: cognitive slowing, confusion	Yes: thyroid hormone replacement
Vitamin B12	B12 deficiency dementia: a reversible cause	Yes: B12 injections or supplements
Folate	Folate deficiency: cognitive impairment	Yes: folic acid supplements
Fasting glucose / HbA1c	Diabetes affects brain function	Yes: blood sugar control
FBC	Anaemia: reduces oxygen to the brain	Yes: treat underlying cause
Calcium	Hypercalcaemia causes confusion	Yes: treat calcium disorder
LFT	Hepatic encephalopathy	Yes: treat liver disease
Syphilis serology (RPR/VDRL)	Neurosyphilis: rare but treatable	Yes: antibiotics

When memory loss is more than normal ageing

Warning signs that need urgent assessment

Normal age-related memory changes include occasionally forgetting names or misplacing objects but remembering them later. Concerning features that need prompt evaluation: forgetting recently learned information repeatedly; getting lost in familiar places; difficulty with everyday tasks (managing finances, cooking); personality or behaviour changes; confusion about time, place or people; repeating the same question multiple times in the same conversation.

Dementia: when blood tests are normal

If all blood tests are normal but significant memory impairment persists, the most common diagnoses are Alzheimer's disease (60–70% of dementias), vascular dementia, Lewy body dementia, or frontotemporal dementia. Further investigation may include: cognitive testing (MMSE, MoCA), brain MRI, and in specialist centres, PET scan or cerebrospinal fluid biomarkers (amyloid, tau). Referral to a memory clinic or neurologist is recommended.

Questions to ask your doctor

Have reversible blood test causes been ruled out?
Should I have a formal cognitive assessment?
Do I need a brain MRI?
Should I see a memory clinic or neurologist?

Frequently Asked Questions

Is memory loss always a sign of dementia?

No. Occasional forgetfulness is normal, and many reversible conditions, thyroid problems, B12 deficiency, depression, poor sleep, and stress, cause memory issues that improve once treated.

What blood tests are done for memory problems?

Doctors typically check thyroid function, vitamin B12 and folate, calcium, glucose, and a full blood count to rule out treatable causes before considering cognitive assessment.

When should memory loss prompt a doctor's visit?

See a doctor if memory problems are progressive, interfere with daily life, or are noticed by family: early assessment identifies treatable causes and enables planning if needed.